10. Whey

The byproduct of cheesemaking — fast-absorbing whey protein (β-lactoglobulin, α-lactalbumin), the classic athlete substrate and base of traditional 'whey drinks'.

Whey in 1 minute

What does it provide? Whey is the liquid byproduct of cheesemaking — the greenish-yellow liquid remaining after casein coagulation. Content: whey protein (β-lactoglobulin ≈ 50–55%, α-lactalbumin ≈ 20%, immunoglobulins, lactoferrin, GMP — exact ratios depend on milk source and processing), lactose (≈ 4–5 g/100 ml), calcium, B vitamins. Whey protein is the fastest-absorbing dietary protein (1–2 hours) — classic post-workout choice for athletes. GMP (glycomacropeptide, the N-end of kappa-casein) is prebiotic — Bifidobacterium-elevating. "Sweet whey" (byproduct of rennet-coagulated cheese) and "acid whey" (byproduct of acid/LAB-coagulated cheese) differ in composition.

How much? Fresh liquid whey: 100–300 ml/day. Whey protein supplement: 20–30 g/workout or meal.

When to avoid? Cow's milk protein allergy (strictly); galactosemia (absolute); severe lactose intolerance (choose lactose-free whey or whey protein isolate, which is < 0.1% lactose); severe kidney disease (high protein); ≥ 2 hours separation from iron supplements; infant < 6 months; high-dose supplement + existing hypercalcemia.

Scientific Background

Whey chemistry: whey is the liquid remaining after milk casein coagulation (outline: milk ≈ 80% casein + 20% whey protein).[1773] Content:

• β-lactoglobulin (~ 50–55%) — the most abundant whey protein; high BCAA content (leucine, isoleucine, valine) — initiates muscle protein synthesis. Strong allergen potential.
• α-lactalbumin (~ 20%) — high in tryptophan + cysteine; potential mood effect as serotonin precursor; high biological value.
• Immunoglobulins — regular cow-milk whey contains only ~1–3% Ig; colostrum (the first 1–3 days of milk after calving) contains 10–15% Ig — the "high Ig" framing applies to colostrum, not regular whey.
• Lactoferrin (1–2%) — antimicrobial, iron-binding, anti-inflammatory.[1774]
• Glycomacropeptide (GMP) — from kappa-casein rennet hydrolysis; prebiotic (Bifidobacterium-elevating), phenylalanine-free (PKU-compatible).

Sweet whey vs. acid whey:

• Sweet whey: byproduct of rennet-coagulated cheeses (cheddar, mozzarella, parmesan). pH 6.0–6.5. Contains GMP.
• Acid whey: byproduct of acid-coagulated cheeses (cottage cheese, ricotta, Greek yogurt). pH 4.0–4.6. Does NOT contain GMP (rennet absent).

Clinical studies:

• Muscle protein synthesis: Tang (2009) reports that 20 g whey protein post-workout elevates muscle protein synthesis (MPS) by 100% — gives a faster and larger response than casein.[1767]
• Glycemia: Mignone et al. (2015 World J Diabetes 6(14):1274–1284) review reports that 15–20 g whey protein taken as a pre-meal reduces postprandial glucose and insulin — via gastric-emptying slowing and incretin mediation (GLP-1, GIP).[1769]
• Immunomodulation: Marshall (2004) reports that lactoferrin + immunoglobulin content has mild immunomodulatory effect — infection prevention.[1770]

Microbiome effect: GMP and α-lactalbumin are prebiotic — Bifidobacterium and Lactobacillus-elevating.[1693] Wallace (2018 J Food Sci) reports that whey protein + live LAB combination (as in traditional liquid whey) is synbiotic.[1746]

Lactose content: liquid whey ≈ 4–5 g lactose/100 ml — not lactose-free. WPC: 4–8% lactose; WPI: < 1%; WPH: < 0.5%.

References

[1693] Sanlier N et al. Health benefits of fermented foods2019;59(3):506–527. Crit Rev Food Sci Nutr. Link

In the past, the beneficial effects of fermented foods on health were unknown, and so people primarily used fermentation to preserve foods, enhance shelf life, and improve flavour. Fermented foods became an important part of the diet in many cultures, and over time fermentation has been associated with many health benefits. Because of this, the fermentation process and the resulting fermented products have recently attracted scientific interest. In addition, microorganisms contributing to the fermentation process have recently been associated with many health benefits, and so these microorganisms have become another focus of attention. Lactic acid bacteria (LAB) have been some of the most studied microorganisms. During fermentation, these bacteria synthesize vitamins and minerals, produce biologically active peptides with enzymes such as proteinase and peptidase, and remove some non-nutrients.

[1746] Wallace TC. Health effects of fermented dairy 2018. J Food Sci. 2018.

Review of the health effects of fermented dairy products.

[1767] Tang JE et al. Ingestion of whey hydrolysate, casein, or soy protein isolate: effects on mixed muscle protein synthesis at rest and following resistance exercise in young men2009;107(3):987–992. J Appl Physiol. Link

This study was designed to compare the acute response of mixed muscle protein synthesis (MPS) to rapidly (i.e., whey hydrolysate and soy) and slowly (i.e., micellar casein) digested proteins both at rest and after resistance exercise. Three groups of healthy young men (n = 6 per group) performed a bout of unilateral leg resistance exercise followed by the consumption of a drink containing an equivalent content of essential amino acids (10 g) as either whey hydrolysate, micellar casein, or soy protein isolate. Mixed MPS was determined by a primed constant infusion of l-[ring-(13)C(6)]phenylalanine. Ingestion of whey protein resulted in a larger increase in blood essential amino acid, branched-chain amino acid, and leucine concentrations than either casein or soy (P < 0.05). Mixed MPS at rest (determined in the nonexercised leg) was higher with ingestion of faster proteins (whey = 0.091 +/- 0.015, soy = 0.078 +/- 0.014, casein = 0.047 +/- 0.008\%/h); MPS after consumption of whey was approximately 93\% greater than casein (P < 0.01) and approximately 18\% greater than soy (P = 0.067). A similar result was observed after exercise (whey > soy > casein); MPS following whey consumption was approximately 122\% greater than casein (P < 0.01) and 31\% greater than soy (P < 0.05).

[1768] Phillips SM, Van Loon LJC. Dietary protein for athletes: from requirements to optimum adaptation2011;29(Suppl 1):S29–S38. J Sports Sci. Link

Opinion on the role of protein in promoting athletic performance is divided along the lines of how much aerobic-based versus resistance-based activity the athlete undertakes. Athletes seeking to gain muscle mass and strength are likely to consume higher amounts of dietary protein than their endurance-trained counterparts. The main belief behind the large quantities of dietary protein consumption in resistance-trained athletes is that it is needed to generate more muscle protein. Athletes may require protein for more than just alleviation of the risk for deficiency, inherent in the dietary guidelines, but also to aid in an elevated level of functioning and possibly adaptation to the exercise stimulus. It does appear, however, that there is a good rationale for recommending to athletes protein intakes that are higher than the RDA. Our consensus opinion is that leucine, and possibly the other branched-chain amino acids, occupy a position of prominence in stimulating muscle protein synthesis; that protein intakes in the range of 1.3-1.8 g · kg(-1) · day(-1) consumed as 3-4 isonitrogenous meals will maximize muscle protein synthesis.

[1769] Mignone LE, Wu T, Horowitz M, Rayner CK. Whey protein: the "whey" forward for treatment of type 2 diabetes?2015;6(14):1274–1284. World J Diabetes. 2015. Link

A cost-effective nutritional approach to improve postprandial glycaemia is attractive considering the rising burden of diabetes throughout the world. Whey protein, a by-product of the cheese-making process, can be used to manipulate gut function in order to slow gastric emptying and stimulate incretin hormone secretion, thereby attenuating postprandial glycaemic excursions. The function of the gastrointestinal tract plays a pivotal role in glucose homeostasis, particularly during the postprandial period, and this review will discuss the mechanisms by which whey protein slows gastric emptying and stimulates release of gut peptides, including the incretins. Whey protein is also a rich source of amino acids, and these can directly stimulate beta cells to secrete insulin, which contributes to the reduction in postprandial glycaemia. Appetite is suppressed with consumption of whey, due to its effects on the gut-brain axis and the hypothalamus. These properties of whey protein suggest its potential in the management of type 2 diabetes.

[1770] Marshall K. Therapeutic applications of whey protein2004;9(2):136–156. Altern Med Rev. Link

Whey, a protein complex derived from milk, is being touted as a functional food with a number of health benefits. The biological components of whey, including lactoferrin, beta-lactoglobulin, alpha-lactalbumin, glycomacropeptide, and immunoglobulins, demonstrate a range of immune-enhancing properties. In addition, whey has the ability to act as an antioxidant, antihypertensive, antitumor, hypolipidemic, antiviral, antibacterial, and chelating agent. The primary mechanism by which whey is thought to exert its effects is by intracellular conversion of the amino acid cysteine to glutathione, a potent intracellular antioxidant. A number of clinical trials have successfully been performed using whey in the treatment of cancer, HIV, hepatitis B, cardiovascular disease, osteoporosis, and as an antimicrobial agent. Whey protein has also exhibited benefit in the arena of exercise performance and enhancement.

[1773] Smithers GW. Whey and whey proteins — from "gutter-to-gold."2008;18(7):695–704. Int Dairy J. 2008. Link

Review by Smithers (Int Dairy J 2008) on the valorisation of whey and whey proteins (the 'gutter-to-gold' journey of the title). Once regarded as waste, whey became a valuable raw material following environmental regulation and advances in science; whey proteins (e.g. beta-lactoglobulin, alpha-lactalbumin, lactoferrin) possess important nutritional and functional properties and have many applications in the food industry and in health promotion.

[1774] Madureira AR et al. Bovine whey proteins — overview on their main biological properties2007;40(10):1197–1211. Food Res Int. Link

Review by Madureira et al. (Food Res Int 2007) on the main biological properties of bovine whey proteins. The major whey proteins (beta-lactoglobulin, alpha-lactalbumin, serum albumin, immunoglobulins, lactoferrin, lactoperoxidase) display a range of health-promoting effects, including antimicrobial and antiviral action, stimulation of the immune system, anticarcinogenic activity and other metabolic features.