Wheying the Positives

Current research on the links between dairy and health point to a major role for whey. Although whey contains vitamins and minerals, its proteins are emerging as the nutritional powerhouse. In vitro, animal and limited human studies indicate that whey proteins and peptides exhibit antimicrobial, antiviral, immune-modulating and anticancer activities, and may contribute to cardiovascular and gastrointestinal health, physical performance and weight management.

Whey begins as a watery mix of lactose, proteins, lipids, vitamins and minerals. Whey's initial claim to nutritional fame is its   high-quality protein, with a protein efficiency ratio (PER) of 3.2 and a protein digestibility corrected amino acid score (PDCAAS) of 1.14, and its calcium content. But examining its individual proteins and fractions reveals numerous candidates for added nutritional value and health-promotion.

The most abundant protein is beta-lactoglobulin at 50% to 55%, followed by alpha-lactalbumin at 20% to 25%. Both are rich in essential amino acids (EAAs) and branched-chain amino acids (BCAAs). Beta-lactoglobulin binds fat-soluble vitamins, and alpha-lactalbumin binds calcium, zinc and other minerals, making them more bioavailable. Whey protein is comprised of 10% to 15% immune-enhancing immunoglobulins (Igs) and 5% to 10% bovine serum albumin with fat-binding properties and EAAs. Other significant minor components include: glycomacropeptide (GMP), a casein-based peptide that lacks phenylalanine; lactoferrin (Lf), an iron-binding protein with antimicrobial, prebiotic and antioxidant properties; lactoperoxidase, a secretory enzyme which inhibits the growth of iron-dependent bacteria; and lysosome, also with immune-enhancing properties.

The litany of potential health benefits is long. Igs, Lf, lactoperoxidase, GMP and sphingolipids exhibit antimicrobial and antiviral activity. Whey protein concentrates and isolates, Lf, lactoperoxidase, Igs and GMP participate in host immunity. Cysteine boosts glutathione production, a powerful antioxidant essential to immune response. In laboratory tests, Lf shows significant cancer and HIV inhibition.

On the cardiovascular scene, peptides act as ACE-inhibitors to lower blood pressure and may help control hypertension. GMP and Lf may inhibit platelet aggregation and other peptides may lower cholesterol. For gastrointestinal health, whey contains carbohydrate and noncarbohydrate components with prebiotic activity. Other potential roles for whey protein fractions include: bone mineralization and breakdown, dental health and improved cognitive performance in stress-vulnerable individuals.

Athletes and even couch potatoes may benefit from whey protein. BCAAs, especially leucine, help maintain muscle mass through protein synthesis, which is important for athletes and those on weight-loss programs. Directly metabolized by muscles during exercise, BCAAs may also contribute to muscle recovery after intense exercise and delay central fatigue during prolonged aerobic activity.

Other amino acids found in whey protein may aid muscle growth, fatigue prevention and performance: arginine and lysine may increase the release of anabolic growth hormone; glutamine, a conditionally EAA, may help prevent fatigue and muscle breakdown; and cysteine is essential for antioxidant glutathione synthesis. Additionally, iron-binding Lf provides antioxidant protection from free radicals, a source of muscle injury in athletes.

For weight management, BCAAs not only appear to preserve lean muscle mass but also to influence glucose homeostasis and adipose tissue regulation. Whey may also affect weight management in other ways. Lactose has the lowest glycemic index among sugars, making the estimated glycemic load of whey protein concentrates and isolates very low. Two British studies demonstrated that whey protein is more satiating than casein with higher postprandial levels of appetite-suppressing hormones, cholecystokinin (CCK) and glucagons, such as peptide. GMP, a known stimulator of CCK, most likely contributes to this phenomenon. Other research suggests that the ACE-inhibitory action of whey proteins and fractions may play a part in dairy's antiobesity effects.

Adding whey proteins to infant formulas can "humanize" cow's milk by modifying the whey to casein ratio in cow's milk from 18:82 to that of mature human milk, 60:40. This strategy increases alpha-lactalbumin, the primary protein in breast milk, and Lf in a cost-effective manner. However, this ratio does not achieve parity with the EAA profile of breast milk yet interestingly, a ratio with less whey protein, 48:52, does. Alternately, some manufacturers choose to add whey protein fractions and/or amino acids to derive the best match to breast milk.

Infants with special needs also benefit from whey proteins. For premature infants, a higher whey-protein formula helps to prevent excessive plasma levels of tyrosine and phenylalanine, and elicits metabolic responses similar to human milk. Hydrolyzed whey-protein formulas are effective in treating infants and children with cow's milk allergy, and GMP's lack of phenylalanine makes it suitable for use by phenylketonurics.

At the other end of the age spectrum, easy-to-digest whey protein offers nutrition to seniors. Its high-quality protein alone merits its inclusion in diets for seniors who typically do not consume adequate protein. Beyond offsetting the compromised immunity and muscle loss from a lack of protein during aging, whey components may improve intestinal health and positively impact many chronic diseases, such as hypertension, heart disease, osteoporosis and cancer. Studies suggest that whey protein could increase glutathione to protect against oxidative stress in those with Alzheimer's disease.

Angela M. Miraglio, M.S., R.D., ([email protected]) is a Fellow of the American Dietetic Association from Des Plaines, IL. Her firm, AMM Food & Nutrition Consulting, provides communications and technical support to the food and beverage industry.

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