Milk powder consumption and nutritional value and digestive comfort in older adults

A new study comparing the addition of cow, goat, or sheep whole milk powder to the diets of older women, for digestive comfort, nutritional status, and metabolism has commenced.

This study is a collaboration between Massey University’s Riddet Institute and the University of Otago . A grant of $1,410,978 has been awarded by the High-Value Nutrition (HVN) Ko Ngā Kai Whai Painga National Science Challenge and the industry partner NIG Nutritionals Limited (NIGN) . The whole milk powders are provided by NIGN (goat), Miraka (cow) and Spring Sheep Milk Co (sheep) . The project aligns with the HVN aim of developing high-value foods with validated health benefits to drive economic growth . Consuming milk confers nutritional and digestive health benefits in infants and children . However, the longer-term impact of milk intake on nutritional benefits and digestive comfort in older adults is less known . Older adults – and older women in particular – often avoid milk for perceived adverse health reasons . In old age, milk avoidance is associated with low intakes of protein, calcium, and other important nutrients, lower muscle mass and strength and increased fracture risk . In addition, older adults do not digest or metabolise protein as well as younger people do . Increasing milk intake by older adults, being high in protein and other important nutrients and being easy to digest, may be a solution to these issues . The 60-plus age group is also a growing market segment in New Zealand and Asia, highlighting the commercial potential of older adult nutrition for the dairy industry . The study will be the first of its kind . It builds on research at the Riddet Institute under the MBIE-funded New Zealand Milks Mean More Endeavour programme (NZ3M) that milk from different species have differing composition and structural assemblies (such as casein micelles) that could lead to differences in nutrition and digestive comfort . NZ3M research has shown that compositionally and in structural assemblies, goat, cow, and sheep milk are different . In addition, sheep milk has a higher protein and lipid content than cow or goat milk . NZ3M scientists have also established that the acid reaction in the stomach results in differences in gastric digestion of casein and whey proteins (two major milk proteins) between goat, sheep, and bovine milk . In experiments simulating the human stomach, cow milk forms a casein curd that tends to be harder than goat and sheep milk gastric curds . This observation means the rate at which the digestive system can process milk curds and pass them from the stomach to the small intestine is likely to differ by milk species . This effect may result in nutrients, such as amino acids, appearing in the blood at different rates due to the hardness of the casein curd forming in the stomach and how quickly it breaks down . The rate of milk protein breakdown in the stomach may influence digestive comfort, and the rate, amount, and type of amino acids appearing in the blood may influence skeletal muscle building in older women . The Department of Human Nutrition, University of Otago, Dunedin, will conduct the twelve-week study collaborating with the Department of Medicine, University of Otago, Christchurch . Four groups of about forty older women aged 60 and older will consume milk twice a day, and a control group will consume their habitual diet but not the milk . Participants will record their experiences for digestive comfort and general well-being . Nutrient absorption, nutritional status, and skeletal muscle function will also be assessed alongside effects on the gut microbiome . The HVN Healthy Digestion Priority Research programme, led by the University of Otago, is a collaborator in the study and will provide expertise in gut microbiome analyses . The study will be completed in 2023 . The study will generate nutritional evidence to help consumers decide between products depending on what they want to achieve . For instance, milk from one species may be more suitable for different nutritional needs or digestive comfort; for example, people who experience digestive discomfort with a particular milk type may better tolerate a different type . The outcomes may support the formulation of unique milk products that will improve nutritional status, digestive comfort, diet quality, quality of life, sleep quality and mood while potentially bringing increased economic benefits to Aotearoa New Zealand’s goat, cow, and sheep producers . The study findings will be published in scientific journals, widely publicised through media releases, and available on the HVN, Otago’s Department of Human Nutrition and Riddet Institute websites and social media .

For more information, please contact Prof Warren McNabb at w.mcnabb@massey.ac.nz +64 6 951 7742

Image supplied by NIG Nutritionals Limited