Focusing on dietary protein quality

The quality of the protein in bovine milk was addressed by two scientists at Alpha Summit 2015. First, Paul Moughan, distinguished professor and director of the Riddet Institute in New Zealand explained the importance of dietary protein quality in nutrition and health.

“Protein is vital to support the health and well-being of human populations,” he said. “However, not all proteins are alike, as they vary according to their origin, animal vs. plant, as well as their individual amino acid composition and their level of amino acid bioavailability. High-quality proteins are those that are readily digestible in a form that can be utilized and contain the dietary essential amino acids in quantities that correspond to human requirements.”

In 2013, the Food and Agriculture Organization of the United Nations recommended that a new, advanced method for assessing the quality of dietary proteins – Digestible Indispensable Amino Acid Score (DIAAS) – replace the Protein Digestibility Corrected Amino Acid Score (PDCAAS) as the preferred method of measuring protein quality.

“The recommendation of the DIAAS method is a dramatic change that will provide an accurate measure of the amounts of amino acids absorbed by the body and an individual protein source’s contribution to a human’s amino acid and nitrogen requirements,” Dr. Moughan said. “This will be an important piece of information for decision makers assessing foods that should be part of a sustainable diet for our growing global population.”

At one point in time, whey was considered a byproduct of cheese. Today, cheese is often made for the sole purpose of obtaining whey, which is a source of highly functional amino acids and bioactive compounds.

He explained that with the PDCAAS method, values are truncated to a maximum score of 1.00, even if scores derived are higher. Using the DIAAS method, researchers are now able to differentiate protein sources by their ability to supply amino acids for use by the body. The DIAAS method is able to demonstrate the higher bioavailability of dairy proteins when compared to plant-based protein sources.

Dr. Moughan added that even with the DIAAS score, you don’t get the whole story about the quality of the protein.

“The single score is based on the limiting amino acid in the protein,” he said. “For example, the leucine component of alpha-lactalbumin has a DIAAS score of 2.00 and the tryptophan component is 5.50. By reporting only the single score of 1.14, which is based on the limiting amino acid valine, the quality of the alpha-lactalbumin is not accurately communicated.

“High-quality data on the bioavailable amounts of individual amino acids in proteins and foods will maximize the information to consumers and health professionals. This will become a lot more important as the food industry increases efforts to support health and different physiological needs.”

Donald Layman, professor emeritus of nutrition, University of Illinois at Urbana-Champaign, said data indicate humans need to make about the same amount of new protein every day for basic lean muscle repair and remodeling. But as we age, the efficiency of building new protein decreases. To reap the benefits of healthy muscles, one must consider the quality of the protein and the quantity of the protein at every meal.

“Below the age of 30, hormones drive growth,” he said. “Even with a low-protein diet, children can still grow and produce new muscle. But as you age, hormones no longer drive muscle growth and the essential muscle replacement is driven by the quality of the diet. Aging reduces the efficiency of protein use, but does not impair the capacity to respond.”

For optimum muscle health and function, research suggests that 30 grams of high-quality protein should be consumed at every meal, and preferably proteins high in the essential amino acid leucine. Formulating foods with Davisco’s BiPRO or alpha-lactalbumin provides a rich source of leucine and may assist with driving muscle synthesis.

Other health and wellness benefits of alpha-lactalbumin consumption are under investigation. John Fernstrom, professor of psychiatry at the University of Pittsburgh School of Medicine, Pittsburgh, discussed protein’s influence on serotonin synthesis in brain neurons and the potential for alpha-lactalbumin in modifying various neurological pathways.

“Serotonin synthesis is directly influenced by its substrate, the amino acid tryptophan,” he said. “And tryptophan levels are directly influenced by blood levels of tryptophan and other amino acids that share a transporter into the brain.

“Alpha-lactalbumin is a rich source of tryptophan, which happens to be the least abundant amino acid in the diet. We know that alpha-lactalbumin produces the biggest increases in brain tryptophan and serotonin, suggesting there are potentially many interesting uses for this dietary protein.”

According to studies presented by Rob Markus, professor of neuropsychology at Maastricht University in The Netherlands, serotonin has been shown to have a positive impact on mood, anxiety and stress control.

Amount of tryptophan in each protein source

“It is possible that alpha-lactalbumin-formulated foods could be designed to improve sleep quality or reduce stress-related overeating, among other well-being benefits,” he said.

Another opportunity is in the treatment of epilepsy.

“Recurring seizures is the symptom of this central nervous system disorder,” said Ilo Leppik, professor of pharmacy and neurology at the University of Minnesota, Minneapolis. “We have proposed a human study to investigate the potential mechanism of alpha-lactalbumin with improving sleep and functioning as an antidepressant. This could, in turn, reduce the occurrence of seizures, similar to how many current medications and even medicinal marijuana function in the treatment of epilepsy.”

Mr. Davis concluded Alpha Summit 2015 by noting, “High-purity alpha-lactalbumin will revolutionize our whey protein capability, allowing us to partner with customers in developing new products for the infant formula industry as well as other functional foods. This will naturally lead to our next generation of products, which are well on their way to commercialization.”