Dairy Discoveries: The latest science on dairy proteins

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Without doubt, the biggest science story of 2020 was the long-running mystery serial that is COVID-19. From the initial sequencing of the SARS-CoV-2 genome through the elucidation of its pathogenesis to the “warp-speed” development of vaccines to fight it, the coronavirus tale has been a ripsnorting page-turner for the ages. And its final chapter has yet to be written.

But it’s not the only narrative that played out in laboratories across the country over the past year. Quietly, doggedly, and under the media’s radar, nutrition research continued apace, generating new insights that bolster not only the health-and-wellness industry, but the health of its consumers, as well.

Such has certainly been the case with respect to research into dairy proteins and their mounting list of benefits. And the knowledge that research keeps uncovering is more relevant now than ever.

Research Keeps Rolling

Uncovering knowledge is nothing to dairy-nutrition researchers, and not even a global pandemic could pull the brakes that.

As Kristi Saitama, vice president, global ingredients marketing, U.S. Dairy Export Council (Arlington, VA), says, “The U.S. dairy industry has a legacy of being research-centric—from nutrition science to product performance to market and consumer insights. And while challenges have hit the food sector and other industries, research on dairy proteins, along with our commitment to future research, continues strong.”

Case in point: Using dairy-industry funding, scientists completed a new landscape survey¹ in the first half of 2020 shedding light on how dairy proteins compare to 16 other protein ingredients in their degree of processing and environmental impact, tracing the ingredients from post-harvest through protein-powder production.

And among the lessons learned: “U.S. dairy proteins may have a similar environmental impact to plant proteins when considered from the perspective of nutritional quality rather than according to the food’s raw weight or caloric content,” Saitama says. At a time when “clean and green” consumers put plant proteins on a pedestal, such findings are worth notice.

The Case for Quality

When it comes to protein quality, dairy’s case is always worth notice. Asked why dairy proteins can hold their own against any of the trendy plant-based options making headlines, Saitama answers, simply, “Nutrition and choice.”

“Dairy and plants are both important to achieving a nutritionally balanced diet,” she concedes, “but given the wide variation in different proteins’ nutritional quality, dairy proteins’ advantage is that they’re nutritionally complete and have benefits backed by a solid body—and many years—of published nutrition research.”

Matthew Pikosky, PhD, RD, vice president, nutrition research, National Dairy Council (Rosemont, IL), agrees, noting that protein quality is at least as critical as protein quantity when building formulations to optimize healthy aging, muscle growth, exercise recovery, and more.

And what determines a protein’s quality? As Pikosky explains, it comes down to “the full array of essential amino acids in sufficient amounts required by the body, the digestibility of the protein, and the bioavailability of the digested and absorbed amino acids derived from it.”

On those counts, he says, dairy proteins like whey and casein, as well as protein ingredients made from milk, outscore other proteins not only according to established measures like the PDCAAS (protein digestibility corrected amino acid score), but per newer and more accurate scoring methods like the DIAAS (digestible indispensable amino acid score).²

New Research for Older Folks

Pikosky notes that while science has long validated dairy proteins’ efficacy at promoting the muscle recovery and “preferential changes in body composition” that athletes and fitness enthusiasts value, dairy proteins’ ability to support muscle health in middle-aged and older adults—who face the age-related loss of muscle mass and function known as sarcopenia—also rests on strong evidence.

“Regarding the value of dairy proteins in middle-aged to older adults,” he says, “recent studies have demonstrated a benefit for whey protein in mitigating the negative impacts of physical inactivity due to significant reductions in usual daily activity or short-term bed rest similar to what may happen with acute hospitalization or illness, and in improving recovery during rehabilitation and return to normal activity.”^3,4

Such findings are especially notable in the current health environment, not only for their implications on helping older COVID survivors restore their earlier vitality, but in light of how lockdown-driven restrictions have limited people’s access to gyms and public spaces, as well as to physical activity more generally, Pikosky says.

A Metabolic Connection

And an even fresher study⁵—published in July of 2020—adds dairy protein’s metabolic benefits to the healthy-aging discussion. The study not only highlights the importance of protein quantity and quality to optimizing aging, inactivity, and bed-rest outcomes, but suggests a role for the nutrient in blood-glucose management, as well. As Pikosky says, “The research showcases the benefits of whey protein as a high-quality, versatile protein ingredient that can readily be used by these populations to help support muscle health.”

Among the study’s lessons that stand out to Pikosky is the distinction it makes between the value of continuing to adhere to the RDA (recommended dietary allowance) for protein—which specifies the level required to prevent deficiency—and the growing body of evidence for recommending higher protein intakes “to support maintenance of muscle mass and function,” he explains.

How much higher? The research suggests a minimum protein intake of 1.0 to 1.2 g of protein per kilogram of body weight per day (g/kg/d) in healthy older adults, and as much as 2.0 g/kg/d in those with severe illness, injury, or marked malnutrition. By contrast, RDA is 0.8 g/kg/d for adults over 18, or about 2.3 oz for a 180-lb adult.

“The study also discusses the importance of consuming around 30 grams of high-quality protein at each meal to efficiently provide targeted amounts of highly digestible and bioavailable essential amino acids—and leucine, in particular—as a practical strategy to support muscle health,” Pikosky continues, “with the authors specifically calling out the value of whey protein.” Not only does it comprise a high proportion of leucine; in the case of whey protein isolate, it has little lactose and a neutral flavor, too.

As for those juicy findings linking dairy protein and metabolic health, Pikosky notes that while both carbohydrate and protein metabolism raise blood glucose levels, stimulate insulin, and affect muscle metabolism, shifting intake toward a more balanced ratio between the two—read: toward more protein—can better modulate postprandial blood glucose levels in a way that’s beneficial to older adults, “as they typically experience decreases in muscle mass, physical activity, and insulin sensitivity that impair blood glucose management and thereby increase the risk for type 2 diabetes,” he says.

Path Forward

Looking ahead, Pikosky suspects that inquiry into protein quality’s role in supporting muscle and metabolic health—particularly in older adults—will continue. After all, he points out, “Current projections⁶ indicate that the population aged 85 and older will grow from 5.8 million in 2010 to 19 million in 2050. Interventions to help maintain health for this age group have broad implications for public health and healthcare expenditures.”

Saitama agrees, adding that dairy proteins have a role to play. “Especially when we think of innovative foods that meet the nutritional needs of older adults and seniors,” she says, “every bite counts. So nutritional quality truly makes a difference.”

References

1. Survey
2. Phillips SM. “Current concepts and unresolved questions in dietary protein requirements and supplements in adults.” Frontiers in Nutrition. Published online May 8, 2017.
3. Arentson-Lantz EJ et al. “Improving dietary protein quality reduces the negative effects of physical inactivity on body composition and muscle function.” The Journals of Gerontology: Series A, vol. 74, no. 10 (September 2019): 1605–1611
4. Oikawa SY et al. “A randomized controlled trial of the impact of protein supplementation on leg lean mass and integrated muscle protein synthesis during inactivity and energy restriction in older persons.” The American Journal of Clinical Nutrition, vol. 108, no. 5 (November 1, 2018): 1060–1068
5. Phillips SM et al. “Optimizing adult protein intake during catabolic health conditions.” Advances in Nutrition, vol. 11, no. 4 (July 1, 2020): S1058–S1069
6. Houchins JA et al. “Diet modeling in older Americans: the impact of increasing plant-based foods or dairy products on protein intake.” Journal of Nutrition, Health, and Aging, vol. 21, no. 6 (2017): 673-680