Raising your albumin levels with egg whites - Can you do it?

I had to do a good amount of digging to find this info...

I've been trying to find a good way to keep Jake's albumin levels up, and wanted to know if egg powder could work as well as regular egg whites, because... raw eggs just gross me out. Ever since I was a kid and saw that one scene from Rocky where he makes the raw egg shake.... eugh, I get the willies just thinking about it.

I'd seen raw egg white powder at Trader Joe's, and I've heard that raw egg white is 100% albumin! So I wanted to know if raw egg white could do the same thing as regular egg white.

I still don't know the answer for that (meaning, is powdered egg white just as effective as raw egg white) but it DOES seem to be beneficial for raising albumin levels.

Please note, if you have cirrhosis, please DO NOT try to consume RAW egg whites, just because you are at a very high risk for a bacterial infection, and God forbid you wind up with Salmonella poisoning. You can die from eating raw oysters when you have stage 4 cirrhosis, because you can wind up with sepsis, and I just looked up salmonella and sure enough this can cause sepsis also, so.... personally I wouldn't chance it!!! 

This is the part I had to dig for (it's in the study below, I'm just copying and pasting this part):

In another study, egg albumin-powder supplementation successfully increased serum albumin in peritoneal dialysis patients but unlike liquid egg whites, the egg albumin powder did not decrease serum phosphorus levels that may be related to phosphorus-based additives (Gonzalez-Espinoza et al. 2005).




 The full study is below, but before you read that, I want to show you, I just discovered they actually make ALBUMIN SUPPLEMENTS.... and it has good reviews.  You can see it by CLICKING HERE.  I'm just seeing this on Amazon for the first time today (11-17-17). I just saw it while looking for powdered egg whites, and today is the first time I actually typed in "albumin" instead of "powdered egg whites." I wish I had tried that a long time ago!

It's helpful to know why you need albumin. Michael Linares does a good job of explaining why you need it, in the video below. Though I disagree that a liver transplant is the best thing you could do for someone who needs help, I do like his videos and they're really informative.  And I LOVE it that he teaches Med students that it's important to educate them about what's going on, and encourage them to make healthier choices.


Basically, albumin acts like a magnet that attracts water and fluid into the veins. But when you don't have that magnetic pull, the fluid leaks all over the body. Albumin also transports drugs, and binds heavily to calcium. So, if you lack albumin, your calcium levels will go down, and your ability to transport drugs will also go down. A normal level albumin level is 3.5 to 5.0 (same as your potassium). 




What kills me is how doctors give albumin while you're in the hospital, but ONLY while you're in the hospital. Shouldn't they be either giving patients some of this stuff to take home with them, so they don't wind up BACK in the hospital, or giving you some kind of supplement for it, or a recommendation of some sort, like for powdered egg whites (which is PURE albumin)????

But I guess if people stopped needing to do those paracentesis procedures, they'd lose a ton of revenue!! (No offense to Michael Linares, I don't wanna say anything bad about this guy cause he is so damn helpful... he really tries to let people know what's going on, which most doctors don't do : /).

DIETARY EGG WHITES FOR PHOSPHORUS CONTROL IN MAINTENANCE HAEMODIALYSIS PATIENTS: A PILOT STUDY

Lynn M. Taylor, MS, RD, LD,¹ Kamyar Kalantar-Zadeh, MD, MPH, PhD,^3,4,7 Theodore Markewich, BA,¹ Sara Colman, RD,² Debbie Benner, RD,² John J. Sim, MD,⁵ and Csaba P. Kovesdy, MD⁶

Author information ► Copyright and License information ►

The publisher's final edited version of this article is available at J Ren Care

See other articles in PMC that cite the published article.

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SUMMARY

Background

High dietary protein intake is associated with greater survival in maintenance haemodialysis (MHD) patients. High-protein foods may increase dietary phosphorus burden, which is associated with increased mortality in these patients. Hypothesis is: an egg white based diet with low phosphorus to protein ratio (<1.4 mg/g) will lower serum phosphorus without deteriorating the nutritional status in MHD patients.

Objective

We assessed serum phosphorus and albumin levels in MHD patients who agreed to ingest one meal per day with pasteurised liquid egg whites without phosphorus additives, as principal protein source.

Methods

Thirteen otherwise stable MHD patients with serum phosphorus >4.0 mg/dl agreed to consume eight ounces (225 g) of pasteurised liquid egg whites one meal per day for six weeks. Recipes were suggested to improve diet variety.

Results

Thirteen participating patients included seven women, three African Americans and five diabetics. Twelve patients exhibited drop in serum phosphorus. Mean population fall in serum phosphorus was 0.94 mg/dl, i.e. from 5.58 ± 1.34 (mean ± SD) to 4.63 ± 1.18 (p = 0.003). Serum albumin showed an increase by 0.19 g/dl, i.e. from 4.02 ± 0.29 to 4.21 ± 0.36 g/dl (p = 0.014). Changes in phosphorus pill count were not statistically significant (p = 0.88). The egg white diet was well tolerated, and recipe variety appreciated.

Conclusion

Pasteurised liquid egg whites may be an effective diet component lowering serum phosphorus without risking malnutrition. Controlled trials are indicated to examine egg white based dietary interventions in MHD patients at home or during haemodialysis treatment.

Keywords: Dietary intervention, Pasteurised liquid egg whites, Phosphorus, Phosphorus-to-protein ratio, Protein, Protein-energy wasting

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INTRODUCTION

In individuals with chronic kidney disease (CKD) who undergo maintenance dialysis treatment, a low dietary protein intake is associated with poor survival (Kopple 2001; Shinaberger et al. 2006). Inadequate protein intake may be caused by anorexia related to inflammation (Kalantar-Zadeh et al. 2004), or as a result of imposed dietary restrictions to control phosphorus (Shinaberger et al. 2008), potassium (Noori et al. 2010a) or fluid intake (Kalantar-Zadeh et al. 2009). Low-protein intake can lead to hypoalbuminaemia and protein-energy wasting (PEW) (Kalantar-Zadeh K et al. 2004; Fouque et al. 2008). The PEW per se may engender or aggravate inflammatory and oxidative processes leading to endothelial dysfunction, cardiovascular and thromboembolic events and death (Ling et al. 2004; Kalantar-Zadeh et al. 2007a; Kovesdy et al. 2009). Malnutrition and inflammation are also related to poor quality of life in dialysis patients (Kalantar-Zadeh et al. 2001; Kalantar-Zadeh & Unruh 2005; Rambod et al. 2009; Noori et al. 2010c). Hence, the so-called malnutrition-inflammation cachexia syndrome has been implicated as a powerful indicator of poor clinical outcome in maintenance dialysis patients (Kalantar-Zadeh et al. 2003a). Dialysis patients with a higher protein and possibly energy intake usually have a higher body mass, larger nutritional reserve, including greater protein mass and higher serum albumin level, and better survival (Kalantar-Zadeh et al. 2003a, 2003b; Kalantar-Zadeh et al. 2005a; Rambod et al. 2008). Hence, dietary interventions to improve nutritional status are urgently needed (Kalantar-Zadeh et al. 2005b).

Foods high in protein are also a main source of dietary phosphorus (Kalantar-Zadeh et al. 2010). Hyperphosphataemia is a common problem in individuals with advanced CKD (Hruska & Teitelbaum 1995; Moe et al. 2006). Gradual decline in renal phosphorus clearance during the progression of CKD leads to increased serum phosphorus concentrations (Levin et al. 2007; Kovesdy et al. 2010a), leading to active vitamin D deficiency, hyperparathyroidism and renal osteodystrophy (Hernandez et al. 2005; Kovesdy & Kalantar-Zadeh 2008). Hyperphosphataemia may also contribute to worsening vascular calcification (Shantouf et al. 2010) and increased risk of cardiovascular morbidity (Block et al. 1998; Block et al. 2004; Achinger & Ayus 2006; Kalantar-Zadeh et al. 2006; Hruska et al. 2007). Hence, correction and prevention of hyperphosphataemia via dietary intervention is a main component of the management of dialysis patients. However, imposing dietary phosphorus restriction is often associated with a reduction in dietary protein intake. The latter can lead to malnutrition and PEW (Kalantar-Zadeh et al. 2003a; Shinaberger et al. 2006). It is thus important to examine sources of dietary protein that are associated with the least phosphorus burden, especially since a recent study showed that higher dietary phosphorus intake or foods with higher phosphorus-to-protein ratio are associated with increased death risk in dialysis patients (Noori et al. 2010b). Egg whites are a good source of biologically high-value protein with a relatively low phosphorus-to-protein ratio (<2 mg/g) and low-cholesterol content (Kalantar-Zadeh et al. 2010; Noori et al. 2010d). Hence, we conducted a pilot project among maintenance haemodialysis (MHD) outpatients of a dialysis clinic and examined the hypothesis that when dialysis patients substituted pasteurised liquid egg white for meat at one meal per day, serum phosphorus level would decrease while serum albumin level would remain constant or increase.

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METHODS

PARTICIPANTS

All MHD patients treated at DaVita Carroll County Dialysis Centre, Westminster, MD, who had undergone haemodialysis treatment for at least three months were invited to participate in this project. In order to be eligible, serum phosphorus of the MHD patient had to be ≥ 4.0 mg/dl. The main exclusion criterion was egg allergy. Participants were required to adhere to the intervention guidelines and agreed to the addition of pasteurised liquid egg white as a substitution for meat during one meal per day for at least six weeks. Fourteen MHD patients, who met the inclusion and exclusion criteria, agreed to participate in this project, out of whom, 13 subjects completed the six weeks of the intervention. One candidate was excluded from analyses due to a prolonged hospitalisation at the initial stages of the project and unrelated to the project.

DATA COLLECTION

The project included a baseline phase of up to four weeks for data collection and a diet intervention phase of six weeks. During the baseline phase, serum concentrations of phosphorus and albumin were recorded. Each participant maintained daily records of food and phosphorus binder intake, received weekly blood draws throughout the six weeks of diet supplementation.

Final blood work was collected at the conclusion of the study.

DIETARY INTERVENTION

All participants were instructed to consume eight ounces of pasteurised liquid egg whites as a meat replacement at one meal each day. Recipe suggestions were provided for smoothies and also for cooking. Participants continued to record consumption in daily food diaries.

The pasteurised liquid egg white product used in this study was AllWhites™ manufactured and distributed by Crystal Farms (Lake Mills, WI, USA), an off-shelf marketed product available in the dairy section of grocery stores. According to the manufacturer information on its publicly accessed website (http://www.betterneggs.com), it constitutes 100% liquid egg whites without preservatives or additives. Each eight oz serving contained 120 kcal, 380 mg sodium, 360 mg potassium, 4 g carbohydrates, 24 g protein and 34 mg phosphorus (data based on United States Department of Agriculture SR-21 nutrient database).

SERUM PHOSPHORUS AND ALBUMIN, AND PHOSPHORUS BINDER

For each participant, the mean of all serum phosphorus and albumin levels during the preintervention period was calculated as the baseline levels. The same biochemical levels were also recorded at the end of the dietary intervention phase, and the change in the levels for each patient was calculated. The change in the daily intake of phosphorus binders, averaged over the entire week, was calculated during the six weeks of intervention and three weeks of post-intervention.

STATISTICAL ANALYSIS

A paired t-test was used to assess the meaningfulness of the change in serum phosphorus and albumin levels. The Wilcoxon Signed-Ranks test was used to confirm the t-test. Similar analyses were performed for the changes in the averaged daily phosphorus binder intake. A p value <0.05 was considered statistically significant.

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RESULTS

The 13 participating patients included seven women (54%), three African Americans (23%) and five diabetics (38%). Patients’ mean age was 62 years ranging from 35 to 85 years. Table 1 shows baseline and post-intervention serum concentrations of phosphorus and albumin as well as the averaged counts of the phosphorus binder pills in each of the 13 participating patients. As shown in Figure 1, all but one patient exhibited a drop in serum phosphorus by the end of intervention. Figure 2 shows the change in serum albumin. In 10 patients, serum albumin increased, whereas in one patient, it decreased and in two patients, no change occurred. Table 2 and Figure 3 show that longitudinal changes in daily phosphorus binder pill counts over the nine weeks of observation. In general, no major changes in the pill count were observed. Table 3 shows the results of the statistical analyses. Serum phosphorus dropped by 0.94 mg/dl, i.e. from 5.58 to 4.63 (p = 0.003). Serum albumin showed an increase by 0.19 g/dl, i.e. from 4.02 to 4.21 g/dl (p = 0.014). Changes in phosphorus pill count were not statistically significant (p = 0.88). The egg white diet was well tolerated and patients reported that they enjoyed the variety of both smoothie and cooked options provided.

Figure 1

Change in serum phosphorus concentrations from baseline to postintervention in each of the 13 participating patients.

Figure 2

Change in serum albumin concentrations from baseline to postintervention in each of the 13 participating patients.

Figure 3

Longitudinal changes in phosphorus binder pill counts, over the entire week, in 13 participating patients.

Table 1

Baseline and postintervention serum concentrations of phosphorus and albumin as well as the averaged counts of the phosphorus binder pills in each of the 13 participating patients.

Table 2

Changes in phosphorus binder pill count over the nine weeks of the study.

Table 3

Baseline and posttrial serum concentrations of phosphorus and albumin and averaged counts of the phosphorus binder pills in each of the 13 participating patients.

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DISCUSSION

We conducted a pilot dietary intervention in a small group of MHD patients in an outpatient dialysis clinic and found that when MHD patients substituted pasteurised liquid egg whites for meat at one meal per day, serum phosphorus level decreased significantly by 0.9 mg/dl, whereas serum albumin level tended to increase. To our knowledge, this is the first study that examines the effect of an egg white based diet on improving phosphorus control and nutritional status in dialysis patients, and our findings may have important clinical and nutritional implications in the care of CKD patients.

In CKD patients, both the PEW (Kalantar-Zadeh et al. 2003a; Fouque et al. 2008) and the ‘Mineral and Bone Disorders’ (MBD) (Levin et al. 2007; Moe et al. 2007) are common and related to high mortality (Block et al. 2004; Kalantar-Zadeh et al. 2005a; Melamed et al. 2006; Shinaberger et al. 2006; Kalantar-Zadeh et al. 2006). The MBD develops with worsening hyperphosphataemia as a result of inadequate renal phosphorus clearance, leading to increased activation of fibroblast growth factor, FGF-23, and subsequent inhibition of 1-alpha hydroxylation of 25-hydroxy vitamin D, secondary hyperparathyroidism and renal osteodystrophy (Hruska & Teitelbaum 1995; Gupta et al. 2004; Gutierrez et al. 2005). On the other hand, PEW is believed to result from inadequate protein intake (Ikizler 2004) due to anorexia from the uraemic state (Kalantar-Zadeh et al. 2004) and other conditions that restrict oral food ingestion or metabolism in MHD patients, and is usually associated with hypoalbuminaemia, chronic inflammation, sarcopenia and weight loss (Kalantar-Zadeh et al. 2003a; Ikizler 2005). Hence, the restriction of dietary phosphorus intake while increasing dietary protein intake is recommended to MHD patients (Kalantar-Zadeh et al. 2010; Noori et al. 2010d). Nonetheless, dietary prevention of MBD may be at the expense of worsening PEW, and vice versa, since dietary phosphorus restriction may lead to malnutrition, while higher protein intake to improve nutritional status may lead to hyperphosphataemia. This therapeutic conundrum, which is encountered frequently during the medical care of dialysis patients, has confused both patients and healthcare providers (Martin & Reams 2003). Many nephrologists and dietitians are not sure whether they should reinforce dietary restrictions in their MHD patients (which often includes significant protein restriction) in order to achieve a lowered serum phosphorus within the recommended target zone (Martin & Reams 2003) or whether they should liberalise or encourage protein intake in order to improve nutritional status and prevent hypoalbuminaemia and PEW (which is associated with elevated death risk). Indeed, the lower mortality in African American dialysis patients may be related to their higher protein intake at the expense of worsening hyperphosphatemia (Kalantar-Zadeh et al. 2007b). Indeed, a recent study showed that the risk of controlling serum phosphorus by imposing dietary protein restriction may outweigh its benefit in MHD patients leading to increased death risk (Shinaberger et al. 2008). Hence, our finding may suggest that an egg white based diet is an appropriate reconciliation between high-protein diet to improve PEW and low-phosphorus diet to improve MBD.

It is important to note that a reduced dietary protein intake may also be the result of poor appetite that happens commonly in MHD patients, for instance as a result of chronic inflammation, independent of restricting or liberalising dietary intake (Kalantar-Zadeh et al. 2004; Carrero et al. 2007). Indeed, very low serum phosphorus (<3.5 mg/dl) is a strong correlate of death risk (Kalantar-Zadeh et al. 2006), which may be due to the exceptionally strong effect of PEW, since very low phosphorus levels are usually observed in patients with inadequate food intake. Nevertheless, a rise in serum phosphorus over time is consistently associated with increased mortality (Kalantar-Zadeh et al. 2006), whereas higher protein intake is associated with lower mortality (Shinaberger et al. 2006), probably by virtue of improving nutritional status (Kovesdy & Kalantar-Zadeh 2009). In a recent study, higher dietary phosphorus intake or frequent ingestion of food with a higher phosphorus to protein ratio was associated with increased death risk (Noori et al. 2010b). Hence, our study may have major clinical implications because we showed that meals that include egg whites can improve serum albumin and nutritional status without dietary phosphorus burden.

In a non-vegetarian western diet, over one-half of the dietary phosphorus load originates from animal proteins (Pecoits-Filho 2007). The main food sources of phosphorus are meat, poultry, fish, eggs and dairy products (National Research Council, Food and Nutrition Board 1989). Digestibility of phosphorus from animal-derived foods is higher than that of plant-based proteins (Noori et al. 2010d). Different sources of animal proteins contain different proportion of phosphorus. One large whole egg contains 6 g of protein and 86 mg of phosphorus, i.e. a phosphorus-to-protein ratio of 14.3 mg/g, whereas egg white from one large egg (4 g of protein) contains only 5 mg of phosphorus (phosphorus protein ratio: 1.2 mg/g), indicating that the bulk of egg phosphorus is in the egg yolk (Kovesdy et al. 2010b). Poultry (such as chicken and turkey) contains less phosphorus than red meat (such as beef and veal) and fish. Each 100 g of salmon contains 21 g of protein and 282 mg phosphorus (phosphorus-protein ratio of 13.4 mg/g) (Kovesdy et al. 2010b). Moreover, meat and dairy products are frequently ‘enhanced’ by the addition of phosphate additives (Sullivan et al. 2009; Kalantar-Zadeh et al. 2010), which may markedly increase the total phosphorus content. Similarly, different types of cheese may contain from <100 mg to almost 1,000 mg per serving of combined organic and inorganic phosphorus based on the type of the cheese and its method of processing (Murphy-Gutekunst 2007; Kalantar-Zadeh et al. 2010).

Egg white based diets including the pasteurised liquid egg whites are high in protein and low in phosphorus with a phosphorus-to-protein ratio of <2 mg/g. This ratio is the lowest among virtually all natural sources of high-value dietary protein (Kalantar-Zadeh et al. 2010). Furthermore, the liquid egg whites have no phosphorus additives, which are usually easily (80–100%) absorbable inorganic phosphorus as compared to lower phosphorus absorption in protein from animal sources such as meat, fish and poultry (40–60%) and plants (<40%) (Noori et al. 2010d). Egg white based products are appropriate for dialysis patients and offer a large variety of cooking and preparation styles including smoothies, veggie casseroles and egg salads. In particular, the smoothie recipes may be more nutritionally compatible with the renal diet than commercial supplements. In our opinion, liquid egg whites are an improvement over sports protein bars which can be used as protein and energy supplements but which are problematic for patients with dentures and which do not allow alternate preparation methods (Meade 2007). In another study, egg albumin-powder supplementation successfully increased serum albumin in peritoneal dialysis patients but unlike liquid egg whites, the egg albumin powder did not decrease serum phosphorus levels that may be related to phosphorus-based additives (Gonzalez-Espinoza et al. 2005).

Our pilot project should be qualified for its small sample size, which prevents conclusive statements about the improved phosphorus control with egg whites, even though patient adherence and positive responses were promising. The intervention assignment was not random, there was no control arm, the dietary intervention was rather short (six weeks) and patients and providers were not blinded. A more ideal trial format would include parallel groups with wash-out period followed by cross-over. Nevertheless, the trends in albumin, phosphorus and phosphorus binder pills were observed closely. Changes in serum albumin were likely minimal given the average well-nourished status of the study population with eight of 13 patients having a baseline serum albumin ≥4.0 g/dl. Furthermore, it is likely that at least some drop in serum phosphorus is attributable to the reduction in dietary meat intake during the intervention. Despite all the aforementioned limitations, we believe that our findings are encouraging and should be further examined in larger studies.

In conclusion, we found that dietary egg white in the form of eight ounces of liquid pasteurised egg white product with 24 g of protein was well tolerated as a protein substitute for one meal a day in MHD patients and effectively lowered serum phosphorus by 0.9 mg/dl over six weeks while serum albumin increased. We also felt encouraged by the observation that the egg white product was pleasing and palatable for most patients. Since it is plausible that the risk of controlling serum phosphorus by imposing dietary protein restriction may outweigh its benefit in MHD patients, foods with extremely low phosphorus to protein ratio such as egg whites may provide the most appropriate diet for CKD patients. The persistent association between low-protein intake and worse survival may indicate that methods other than restricting protein intake should be sought to restrict dietary phosphorus intake. Egg white products may be a means to that end, while more attention to nonprotein sources of phosphorus such as food additives or highly processed convenience foods is warranted (Uribarri 2007). Because increased protein intake with a concurrent decline in serum phosphorus appears to be associated with the lowest mortality, egg white based diet may be helpful. In any event, our results underscore the need for well-designed controlled trials to examine the role of egg whites and meals during haemodialysis treatment to control phosphorus and improve nutritional status in MHD patients.

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Acknowledgments

This study was supported by research grants from DaVita Clinical Research, a General Clinical Research Centre (GCRC) grant number M01-RR00425 from the National Centres for Research Resources, National Institutes of Health and a philanthropist grant from Mr. Harold Simmons.

The authors would like to thank DaVita Clinical Research for funding this research and the team and patients of DaVita Carroll County Dialysis who assisted in this study. Special thanks to Dr. Robert Levy for his encouragement and intellectual support for this research. These data were presented in part as a poster at the Spring Clinical Meeting of the National Kidney Foundation, 2008.

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Biographies

Lynn Taylor is a Registered Dietitian with Davita Carroll County Dialysis in Westminster Maryland. She is a member of The American Dietetic Association and The Renal Practice Group. She has coauthored in perspectives: The Journal of the Council of Nephrology Social Workers. She supports chronic kidney disease education by recipe and article submission for newsletters and websites.

Kamyar Kalantar-Zadeh is the Associate Professor of Medicine, Pediatrics & Epidemiology at UCLA David Geffen Schools of Medicine and Public Health. He has received numerous awards including those from National Institutes of Health and National Kidney Foundation. He is a member of the editorial board of several renal journals including AJKD, CJASN, AJN, ACKD, IUN, CN, JREN. He has written more than 150 research papers and lectures frequently on nontraditional cardiovascular risk factors in patients with CKD such as malnutrition, inflammation-cachexia syndrome, iron and anaemia and bone and mineral disorders.

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Footnotes

CONFLICT OF INTEREST

None declared.

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• Noori N, Kalantar-Zadeh K, Kovesdy CP, et al. Association of dietary phosphorus intake and phosphorus to protein ratio with mortality in hemodialysis patients. Clinical Journal of the American Society of Nephrology. 2010b;5:683–692. [PMC free article] [PubMed]
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Another study on egg whites:

Biotechnol Res Int. 2013; 2013: 230142.

Published online 2013 Feb 28. doi:  10.1155/2013/230142

PMCID: PMC3600259

Antioxidant and Hepatoprotective Properties of Tofu (Curdle Soymilk) against Acetaminophen-Induced Liver Damage in Rats

Ndatsu Yakubu, ^{1 ,*} Ganiyu Oboh, ² and Amuzat Aliyu Olalekan ¹

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This article has been cited by other articles in PMC.

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Abstract

The antioxidant and hepatoprotective properties of tofu using acetaminophen to induce liver damage in albino rats were evaluated. Tofus were prepared using calcium chloride, alum, and steep water as coagulants. The polyphenols of tofu were extracted and their antioxidant properties were determined. The weight gain and feed intake of the rats were measured. The analysis of serum alanine aminotransferase (ALT), alkaline phosphatase (ALP), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH) activities and the concentrations of albumin, total protein, cholesterol, and bilirubin were analyzed. The result reveals that the antioxidant property of both soluble and bound polyphenolic extracts was significantly higher in all tofus, but the steep water coagulated tofu was recorded higher. Rats fed with various tofus and acetaminophen had their serum ALP, ALT, AST, and LDH activities; total cholesterol; and bilirubin levels significantly (P < 0.05) reduced, and total protein and albumin concentrations increased when compared with basal diet and acetaminophen administered group. Therefore, all tofus curdled with various coagulants could be used to prevent liver damage caused by oxidative stress.

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1. Introduction

Reactive oxygen species (ROS) have been implicated in more than 100 diseases [1]. Foods (tubers, grains, fruits, and vegetables) provide a wide variety of ROS-scavenging antioxidants such as phytochemical and antioxidant vitamins [2, 3]. The increased consumption of fruits and vegetables, containing high levels of phytochemicals, has been recommended to prevent or reduce oxidative stress in the human body [2–4]. The natural antioxidant defense mechanisms can be insufficient and hence dietary intake of antioxidant components is important and recommended [5].

Liver disease is a worldwide problem. Conventional drugs used in the treatment of liver diseases are sometimes inadequate and can have serious adverse effects [6]. Soybeans are inexpensive and serve as high quality protein source. Soymilk and tofu consumption is increasing in Nigeria due to animal diseases such as mad cow disease, global shortage of animal protein, strong demand for healthy (cholesterol-free and low in saturated fat) and religious halal food, and economic reasons [7]. The greater acceptance of soy foods by the general population is due to increased recognition of the health benefits of soy foods, especially by those who want to reduce their consumption of animal products [8]. Tofu, also known as soybean curd, is a soft cheese-like food made by curdling fresh hot soymilk with a coagulant [9]. Traditionally, in Nigeria, it is produced by curdling fresh hot soymilk with CaCl₂, MgSO₄ alum, or steep water (effluence from pap produced from maize) [10–12]. Tofu is rich in proteins; low in saturated fats; higher in polyunsaturated fatty acids; cholesterol-free; and a good source of β-vitamin, minerals, isoflavones, and antioxidants (carotenoids, vitamins C and E, phenolic and thiol (SH) compounds, and essential amino acids) [8, 12]. It has been demonstrated that phenolic compounds are effective antioxidants, due to the formation of stable phenoxyl radical [13], and that flavonoids have potent antioxidant activities by scavenging hydroxyl radicals, superoxide anions, and lipid peroxy radicals [14]. Soybean products reduce the risk of heart diseases by lowering levels of oxidized cholesterol, which is taken up more rapidly by coronary artery walls to form dangerous plaques [15]. Previous research has shown that soy consumption reduces cholesterol in general while also decreasing the amount of bad cholesterol (low-density lipoprotein, LDL) in the body and maintaining the amount of good cholesterol (LDL) [16, 17].

Acetaminophen is a commonly used and safe analgesic drug, which is known to cause centribular necrosis upon overdose [18]. Its toxicity accounts for many emergency hospital admission and continues to be associated with high mortality. The hepatotoxic effect of acute paracetamol overdose is well known and has been extensively reviewed [19]. However, tofu (soybean product) contains compounds that are valuable antioxidants and protecting molecules, which can trap or destroy free radicals and subsequently protect us from damage due to oxidative stress [9]. In view of this, people have started to take an interest in tofu consumption due to its good nutritional and health benefit to human. Therefore, this research is designed to evaluate its polyphenol distribution and the antioxidant properties in tofu produced using different coagulants, and to compare its hepatoprotective properties on acetaminophen-induced toxicity in rat's liver.

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2. Materials and Methods

The soybeans (Glycine max), TGX923-1E variety, were obtained directly from Ibrahim Badamasi Babangida University, Lapai experimental farm in Niger State, Nigeria. The alum and calcium salt (CaCl₂) were industrial grade, while the steep water was collected from domestically processed pap. The water used in the analysis was glass distilled. The weaning albino rats used were of the same litter origin obtained from the rat colony of the Department of Biochemistry, University of Ilorin, Nigeria.

2.1. Tofu Preparation

Soybeans (2.0 kg) were soaked in water (6 litres) at 20–40°C for 9 hours. The soaked beans were drained, weighed, and ground with grinder; tap water was added at a ratio of 6 : 1 with raw bean and then filtered to separate soy cake from soymilk. The soymilk was subsequently heated to 98°C and maintained for 1 minute before delivering to the mix tank. When cooled to 87°C, 1 litre of soymilk was mixed at 420 rpm with each of the coagulants (50 mL). The mixed solutions were held for 5 seconds and then filled onto tofu trays and allowed to coagulate for 10 minutes. The bean curd was pressed after which the tofu weight was recorded. Tofu was stored in water at 4°C overnight prior to analysis.

2.2. Animals

Twenty-five of 3-week old strain albino rats with an average weight of 50.2 g were used in this study. They were obtained from the animal house of the College of Medicine, University of Ilorin, Kwara State, Nigeria. The animals were housed in metabolic cage in the laboratory under ambient temperature and 12-hour light and dark periodicities. They were fed with commercial rat pellets (Neimeth Livestock Feeds Ltd., Ikeja) and water ad libitum and allowed to acclimatize for 2 weeks. Animal experiments were conducted in accordance with the internationally accepted principle for laboratory animal use and care [20].

2.3. Extraction of Free Soluble Polyphenols

Free soluble phenols were extracted using the method modified by Nwanna and Oboh [21]. About 200 g of each tofu was homogenized in 80% acetone (1 : 2 w/v) separately using chilled Waring blender for 5 minutes. Thereafter, the homogenates were filtered through Whatman number 2 filter paper on a Buchner funnel under vacuum. The residues were kept for extractions of bound phenols. The filtrates were evaporated using a rotary evaporator under vacuum at 45°C until 90% of the filtrates had been evaporated. The extracts were frozen at −40°C.

2.4. Extraction of Bound Polyphenols

These were extracted using the method modified by Nwanna and Oboh [21]. The bound phenolic contents were extracted from the residue from the free soluble polyphenol extracts. The drained residues from soluble free extraction were hydrolyzed directly with 20 mL of 4 M NaOH at room temperature for 1 hour with shaking. The mixture was acidified to PH 2 with conc. HCl and extracted six times with ethyl acetate. The ethyl acetate fractions were evaporated at 45°C under vacuum to dryness.

2.5. Antioxidant Activity

2.5.1. Total Phenol Content

These were determined by the modified method of Nwanna and Oboh [21]. About 0.5 mL of each extract was dissolved in 20 mL of 70% acetone with equal volume of water; 0.5 mL Folin-Cioalteus reagent and 2.5 mL of sodium carbonate were subsequently added and the absorbance was measured after 40 minutes at 725 nm, using tannic acid as standard.

2.5.2. Reducing Property

These were determined by assessing the ability of the tofu extracts to reduce FeCl₃ solution using modified method of Nwanna and Oboh [21]. About 2.5 mL of each extract was dissolved in 20 mL of methanol and mixed with 2.5 mL of 200 M sodium phosphate buffer (PH 6.6) and 2.5 mL of 100% potassium ferricyanide. The mixtures were incubated at 50°C for 20 minutes; thereafter 2.5 mL, 10%, trichloroacetic acid was added and subsequently centrifuged at 650 rpm for 10 minutes; 5 mL of the supernatant was mixed with equal volume of water and 1 mL of 0.1% ferric chloride. The absorbances were then measured at 700 nm, and a higher absorbance indicates a higher reducing power.

2.5.3. Free Radical Scavenging Ability

The free radical scavenging ability of the soluble free and bound extracts against DPPH (1, 1-diphenyl-2-picrylhydrazyl) free radical was also evaluated [22]. About 1 mL of the extract was dissolved in 20 mL methanol and mixed with 1 mL of 0.4 M methanolic solution containing 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radicals. The mixtures were left in the dark for 30 minutes before measuring the absorbance at 516 nm.

2.6. Experimental Design

Animals were weighed and randomly assigned into five groups, namely,

• normal control group (n = 5) was placed on a basal diet of 20 g/day only;
• negative control group (n = 5) was placed on 20 g/day and 100 mg/100 g/day of basal diet and acetaminophen orally administered, respectively;
• treated group 1 (n = 5) was placed on steep water tofu (20 g) and acetaminophen (100 mg/100 g/day) orally administered, respectively;
• treated group 2 (n = 5) was placed on alum tofu (20 g) and acetaminophen (100 mg/100 g/day) orally administered, respectively;
• treated group 3 (n = 5) was placed on calcium tofu (20 g/day) and acetaminophen (100 mg/100 g/day) orally administered, respectively.

The experimental period was 14 days. During the experiment, the weights of the rats were measured two times in a week during the 2 weeks of the experiment.

2.7. Measurements

The mean average weight of the rats was determined at the beginning of the experiment at every 2 days. The weight of the rats was determined using weighing scale (OHAUS MODEL Cs 5000, CAPACITY 500 × 2 g). This was done by placing a container on the scale, with the balance adjusted to zero, after which the rats in each group were placed into container and the measurement taken [23]. Total feed consumed in percentage was calculated using the following formula:

total feed consumed (%) = 100 (feed supplied (20 g) − leftover (g)/feed supplied (20 g).

total weight gain (TWG) in percentage was calculated as

total weight gain (%) = 100 × (final weight − initial weight)/initial weight [24].

On the 15th day, the rats were killed by cervical dislocation, the bloods collected were centrifuged, and the supernatants were collected for the assessment of liver function. In addition, the livers were harvested for histopathological analysis.

2.7.1. Assessment of Liver Function

The serum was used for the assay of marker enzymes (aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), and bilirubin) concentrations using Roche Modular Autoanalyzer. Total protein, albumin, sugar, and total cholesterol were analyzed by using standard randox laboratory kits.

2.8. Statistical Analysis

The results were reported as mean ± SEM (standard error of mean). One-way analysis of variance and least significant difference (LSD) test were used to evaluate the significant difference. Probability levels of less than 0.05 were considered significant.

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3. Results

Table 1 shows the result of antioxidants properties of the tofu studied. The results revealed that the steep water coagulated tofu significantly recorded high total phenols (15.0 ± 2.24%), followed by the alum-coagulated tofu (13.0 ± 2.08), and the calcium salt coagulated tofu appeared significantly higher in free radical scavenging activities of the free soluble phenol (65.5 ± 4.67%). The alum coagulated tofu (47.3 ± 3.97%) and the steep water had the least (38.2 ± 3.57%). Conversely, steep water coagulated tofu significantly recorded higher free radical scavenging activity of the bond phenol (69.1 ± 4.80%), followed by alum coagulated tofu (56.5 ± 3.36%), and calcium salt coagulated tofu had the lowest (27.3 ± 3.02%) free radical scavenging activity of the bound phenol. Also, the reducing power of free soluble and bound phenol of steep water and calcium salt coagulated tofu were not significantly different (0.4 ± 0.20), while alum coagulated tofu had the reducing power of free soluble phenol (0.3 ± 0.17) to be lower than that of bound phenol (0.5 ± 0.30).

Table 1

Antioxidant properties of tofu studied.

The result of total feed intake and total weight gain are presented in Table 2 and revealed that there was decrease in total feed intake (141.8 ± 5.31%) and total weight gain (9.11 ± 1.35%) in rats fed with basal diet and given acetaminophen when compared with those rats fed with basal diet without acetaminophen (total feed intake, 443.8 ± 9.40%; total weight gain, 14.5 ± 1.70%). However, there was a significant increase (P < 0.05) in total feed intake (44.2 ± 2.10–73.5 ± 3.80%) of rats fed with tofu curdled with various coagulants and given acetaminophen orally compared to those rats fed with basal diet and given acetaminophen. In addition, the total weight gain of rats fed with tofu curdled with various coagulants plus acetaminophen decreased significantly (−5.1 ± 1.01–2.1 ± 0.60%) when compared with those fed with acetaminophen (9.1 ± 1.35%).

Table 2

Total feed intake and weight gain of albino rats fed with commercial diet and various coagulated tofu (g/rats/days).

The results of liver function tests of the rats studied are shown in Table 3 and revealed that serum AST, ALT, ALP, and LDH levels of rats treated with basal diet and given acetaminophen orally were quite higher than that of the group treated with basal diet without acetaminophen. In contrast, the rats treated with various tofus and acetaminophen orally had significantly lower levels of AST, ALT, ALP, and LDH when compared with the group treated with basal diet and acetaminophen orally (Table 3).

Table 3

Serum enzyme marker level of rats studied.

The results of serum chemistry of rats studied are presented in Table 4 and revealed that bilirubin (0.153 ± 0.12 mg/dL), cholesterol (243.45 ± 7.00 mg/dL), and glucose (162.68 ± 5.70 mg/dL) levels significantly (P < 0.05) increased in rats treated with basal diet without acetaminophen intubation when compared with those treated with basal diet and acetaminophen intubation. Nevertheless, the content of total protein (3.45 ± 0.80 mg/dL) and albumin (1.65 ± 0.57 mg/dL), respectively, significantly decreased (P < 0.05). In addition, rats fed with various coagulated tofu and acetaminophen showed significant (P < 0.05) reduction in the level of bilirubin, cholesterol, and glucose when compared with rats fed with basal diet and acetaminophen intubation. In contrast, the level of total protein and albumin of rats fed with various tofus and acetaminophen were significantly increased (P < 0.05) when compared with those fed with basal diet and acetaminophen.

Table 4

Serum chemistry level of rats studied.

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4. Discussions

The antioxidant properties of polyphenolic extractions of tofu produced using different coagulants and the effects of these tofus on acetaminophen-induced hepatotoxicity in albino rats were evaluated. Polyphenols, particularly the flavonoids, are among the most potent plant antioxidants. Polyphenol can form complexes with reactive metals such as iron, zinc, and copper reducing their absorption [21]. It seems to reduce nutrients absorption, but excess levels of such elements (metals cations) in the body can promote the generation of free radicals and contribute to the oxidative damage of cell membranes and cellular DNA [25]. In addition, polyphenols also function as potent free radical scavengers within the body, where they can neutralize free radicals before they can cause cellular damage [26]. The results of polyphenolic antioxidant properties of various tofus studied as indicated in Table 1, revealed that steep water coagulated tofu had a significantly higher (P < 0.05) total phenol, followed by alum coagulated tofu, and calcium salt tofu had the least value of total phenol. These values generally compared well with what Shokunbi et al. [9] reported for some varieties of commercial mushrooms (0.01 g/100 g). The results are also in line with the report of Oboh and Rocha [27] on some hot pepper (Capsicum annum, Tepin, and Capsicum pubescens). In contrast, free radical scavenging activity of the free phenols of various types of tofu analyzed had a significantly higher (P < 0.05) calcium coagulated tofu, followed by alum coagulated tofu, and steep water coagulated tofu, which is the least (Table 1). However, the reverse was the case for the bound phenols where steep water coagulated tofu was recorded high, followed by alum coagulated tofu, and calcium-coagulated tofu had the least value of bound phenol (Table 1).

These values are higher than what Oboh and Akindahunsi [28] reported on some commonly consumed green leafy vegetables in Nigeria. Oxidative stress is the state of imbalance between the level of antioxidant defense system and the production of the oxygen-derived species. The increased level of oxygen and oxygen-derived species causes oxidative stress. The finding suggests that various tofus produced using different coagulants are good source of antioxidants and could be used to reduce biological oxidative stress and prevent cellular damage by scavenging free radical activity of the oxidative stress. Table 2 shows the results of total feed intake and total weight gain of rats studied. The result reveals that there was a decrease in total feed intact and total weight gain of the rats fed with basal diet and acetaminophen when compared with those rats fed with basal diet without acetaminophen (Table 2). This drastic reduction in feed intake and total weight gain could be because of overdose of paracetamol intake that generated oxidative stress in rats. The free radicals produced in rats might cause certain abnormality in food consumed and weight gain. It was also observed that rats fed with alum-coagulated tofu consumed the highest amount of tofu in the duration of the experiment, followed by those fed with calcium chloride coagulated tofu, while those fed with tofu coagulated with steep water consumed the lowest amount of tofu (Table 2). The total weight gain of rats fed with tofu produced using different coagulants was significantly higher (P < 0.05) in alum-coagulated tofu, and tofu coagulated with steep water significantly had the least weight gain (Table 2). The higher consumption of alum and calcium chloride coagulated tofu might be because of good taste and odour as indicated in the tofu, and the negative value of weight gain recorded by the rats fed with steep water tofu could be because of very low feed intake. While, the low intake of the tofu coagulated with steep water could be because of the unpleasant odor imparted by the steep water to the tofu. The wide variation for tofu consumed by the various rats could be because of the difference in the taste, nutritional quality, and acceptability of the various coagulated tofu [16, 29]. As shown in Table 3, overdosing rats with 100 mg/mL/day acetaminophen alone for 14 days caused a significant increase (P < 0.05) in the serum marker enzymes (AST, ALT, ALP, and LDH) (Table 3). Increase in AST levels signified liver damage. This finding suggested that the mega doses of acetaminophen administered induce the production of free radicals, which cause damage to the hepatocytes of rats.

This result correlates with the finding of Eriksson et al., [30] that toxicity with acetaminophen occurs when too much of it is taken. The elevations of serum liver enzymes indicate liver damage. This correlates with the report of Sai et al., [31] that a significant increase in serum AST, ALT, and ALP levels suggests liver damage. Under normal therapeutic dose of acetaminophen, the excessive metabolites produced by the cytochrome P-450 system can be reduced by glutathione. However, if acetaminophen is overdosed, the glutathione stores will be depleted and the excessive metabolites will react with the liver macromolecules and cause hepatic cell death. The hepatic cellular enzyme ALP in serum will therefore increase. In addition, the hepatic malondialdehyde level will increase invariably, hence resulting in the generation of free radicals in the body [21]. This suggests that acetaminophen hepatotoxicity appears to be critically dependent on the depletion of cellular glutathione, and a relatively high reduction in the intracellular level of reduced glutathione leads to a situation of oxidative stress [32, 33]. Conversely, a simultaneous administration of albino rats with 100 mg/mL/acetaminophen alongside various tofus produced caused a significant decrease (P ≤ 0.05) in serum AST, ALT, and ALP (Table 3). Decrease in serum marker enzyme levels (liver enzymes) indicates the ability of various tofus to protect the hepatocytes from oxidative damage caused by overdosing rats with acetaminophen. This is an indication that antioxidant mechanism may be involved in the protection of the liver cell by the various tofus from acetaminophen-induced oxidative stress. It was suggested that soy products contain high antioxidant properties, which serve as an extracellular neutralizer of free radicals [34].

In addition, soy food and vegetables had been reported to be rich in many phenols such as flavonoid [35]. Flavonoids have antioxidants capacity that is much stronger than those of vitamins C and E, reportedly used to prevent free radical production [35]. In contrast, the serum LDH level of rats fed with basal diet and acetaminophen was increased significantly (P < 0.05) when compared with those fed with basal diet without acetaminophen (Table 3). This is in line with the findings of Ravikumar et al., [36] that the serum LDH level was elevated in rat administered CCl₄. The increased level of LDH is an indication of abnormality in liver functioning, which may be due to the formation of highly reactive free radicals caused by acetaminophen overdose. The hepatotoxicity of acetaminophen may directly affect the polyunsaturated fatty acids and alter the liver microsomal membranes in the rats. In a reverse case, the LDH levels of rats fed with tofu and acetaminophen were significantly decreased (P < 0.05) when compared with that of rats in group BDA (Table 3), which is a sign of an improvement by the various tofus over the damage done to the liver by acetaminophen. The result of serum total cholesterol level as indicated in Table 4 revealed that there was a significant increase in total cholesterol of rats fed with basal diet and acetaminophen orally when compared to those fed with basal diet without acetaminophen orally administered (Table 4).

The elevation in serum total cholesterol level could be attributed to the ability of acetaminophen to induce the production of free radicals, which results in hypercholesterolemia and the atherosclerosis. This correlates with the findings of Oboh [15] that an increase in the serum levels of cholesterol and LDL is associated with hypercholesterolemia and atherosclerosis, respectively. It is also supported by the findings of Ravikumar et al., [36] that intoxication of rat with CCl₄ elevated total cholesterol levels, which suggests the inhibition of bile acid synthesis and leads to increased level of cholesterol. However, supplementation of tofu curdled with various coagulants and acetaminophen orally administered causes a significant decrease (P > 0.05) in serum total cholesterol, compared to those fed with basal diet with acetaminophen orally administered (Table 4). It indicated that tofus produced using three coagulated agents are capable of preventing acetaminophen inducing oxidative stress and inhibiting bile acids synthesis.

This could be attributed to high antioxidant potential of soybeans, which serve as an extracellular neutralizer of free radicals [37]. This finding is in line with the study of Oboh [15] that the antihypercholesterolemic effect of soy protein was found to decrease the plasma concentrations of LDL as well as the ratio of plasma LDL to high density lipoprotein (HDL). It was reported that flavonoids could protect membrane lipids from oxidation, and a major source of flavonoids is vegetables, fruits, and soybeans [35]. The significant (P < 0.05) reduction in total protein and albumin levels in rats fed with basal diet with acetaminophen intubation, compared to those fed with basal diet without acetaminophen orally administered (Table 4), indicates cellular damage produced. The damage produced might be due to the functional failure of endoplasmic reticulum, which leads to decrease in protein synthesis and accumulation of triglycerides [36]. Increased serum bilirubin level in rats fed with basal diet with acetaminophen intubation (Table 4) could be looked upon as a compensatory/retaliatory phenomenon in response to cellular peroxidative changes, which cause damage to the biliary gland. This is because bilirubin functions in vivo as a powerful antioxidant, antimutagen, and an endogenous tissue protector [37]. Reduction of bilirubin and elevation of total protein and albumin levels in rats treated with various coagulated tofus and acetaminophen orally administered (Table 4) were most effective and stabilized the biliary cell function and endoplasmic reticulum leading to bile acid and protein synthesis [38]. This indicates hepatoprotection. The administration of acetaminophen alone may adversely interfere with protein metabolism probably by inhibiting the synthesis of proteins such as albumin in the liver.

Simultaneous administration of acetaminophen to rats with supplementation of various tofus produced reversed these changes, maybe by increasing protein synthesis. Stimulation has been advanced as a contributory hepatoprotective mechanism, which accelerates regeneration of cells [39]. LDH activities all point to the fact that tofu has hepatoprotective potential against hepatotoxin caused by acetaminophen. It could be possible that a probable mechanism of hepatoprotection of various tofus against acetaminophen-induced damage is the antioxidant activity. The antioxidant activity of the various tofus supplemented may be attributed to the presence of phenolics and flavonoids [40]. Therefore, lower level of serum enzyme markers, total cholesterol, and bilirubin observed in rats on tofu coagulated with various coagulants and acetaminophen orally administered suggested liver damage repair, but steep water coagulated tofu looked more promising in terms of liver repair than other forms of tofu diet. It can be concluded from the present finding that tofus curdled with various coagulants could be efficiently used to prevent liver damage caused by high doses of acetaminophen orally administered after successful clinical trials. In addition, the intake of acetaminophen in excess should be discouraged in homes because of its destructive effects on the liver. Tofu consumption should be encouraged in diets as it can be used as a functional food to prevent liver damage due to its antioxidant properties, and as such, tofu could be recommended for clinical trial.

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Conflict of Interests

The authors declare that they have no competing interests apart from the possible ones already acknowledged below.

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Acknowledgments

The authors would like to acknowledge the Department of Biochemistry, Federal University of Technology, Akure, Ondo State, Nigeria, for providing facilities for this work. One of the authors, Mr. N. Yakubu, is grateful to the Niger State College of Agriculture, Mokwa, Niger State, Nigeria, for financial sponsorship that enabled him to participate in this study.

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I also find it interesting that albumin has a negative charge, like a magnet.

https://www.ncbi.nlm.nih.gov/books/NBK204/

Albumin does not diffuse freely through intact vascular endothelium. Hence, it is the major protein providing the critical colloid osmotic or oncotic pressure that regulates passage of water and diffusable solutes through the capillaries. Albumin accounts for 70% of the colloid osmotic pressure. It exerts a greater osmotic force than can be accounted for solely on the basis of the number of molecules dissolved in the plasma, and for this reason it cannot be completely replaced by inert substances such as dextran. The reason is that albumin has a negative charge at normal blood pH and attracts and retains cations, especially Na⁺ in the vascular compartment. This is called the Gibbs–Donnan effect. Albumin also binds a small number of Cl⁻ ions that increase its negative charge and ability to retain Na⁺ ions inside the capillaries. This enhanced osmotic force causes the colloid osmotic pressure to be 50% greater than it would be by protein concentration alone.

Albumin serves in the transport of bilirubin, hormones, metals, vitamins, and drugs. It has an important role in fat metabolism by binding fatty acids and keeping them in a soluble form in the plasma. This is one reason why hyperlipemia occurs in clinical situations of hypoalbuminemia. The binding of hormones by albumin regulates the amount of free hormone available at any time. Because of its negative charge, albumin is also able to furnish some of the anions needed to balance the cations of the plasma.