On the Road From Analysis and Discovery of Milk Bioactives to New Products and Health Outcomes
By Samara Freeman, Ph.D., UC Davis researcher, symposium coordinator

The symposium on milk bioactives at the recent American Dairy Science Association (ADSA) meeting highlighted different approaches and types of research needed to capture the health value in dairy ingredients and products. Held in San Antonio, TX, the symposium was sponsored by CDRF, Agilent Technologies and Hilmar Ingredients. Participants included analytical chemists, physiologists, food scientists and clinicians.

Bioactive ingredients are structures in food that bring about specific physiological/metabolic effects beyond the traditional view of food as fuel sources. The impetus for focus on bioactives is the burden of chronic, metabolic diseases in the population coupled with rising health care costs. This opens the door to new strategies for preventing diseases and promoting health. Research is continuing to identify unique components in milk, define appropriate health targets and find diagnostics that make sense to deliver health benefits. Mammalian milks nourish and promote the survival of the newborn infant and therefore, inherently contain bioactivities directed towards health. For human health, human breast milk offers a unique glimpse at how these milk components can guide development of the infant gut and immune system at a time when the infant is most vulnerable to infection and metabolic errors. This strategy enables efficiently linking specific milk components to specific health functions. Finding commercially viable bovine sources of bioactives and measuring changes in specific health targets in different age groups and conditions are the next steps.

What bioactive components are in milk? What is the natural variation between breeds and different diets for different bioactives? Exciting technological breakthroughs in the areas of complex carbohydrate analysis provided an example of how we can begin to answer these questions. Complex carbohydrates namely the oligosaccharides (long-chain sugars) are one of the least understood components of milk. Prior to this research, it took years to analyze and document a few carbohydrate structures within milk and even longer to figure out how they were linked to proteins. With new technology, more than 190 different free structures have been identified in a single sample of human milk over the course of lactation. In human milk, free oligosaccharides are the 3rd most abundant component, yet they are not digestible by the infant; they instead direct the developing intestinal profile of bacteria, a critical part of a healthy intestine. Dairy now has targets for breeding cows that can produce a value-added milk containing health promoting, naturally formed oligosaccharides.
Conjugated linoleic acid (CLA), specifically rumenic acid can be analyzed in milk. CLA is a trans fat found in dairy, but it has a different structure than industrial trans fat, and has created significant interest for its anti-cancer and anti-heart disease effects. Medical studies investigating the effects of natural trans fats such as CLA versus those trans fats that are made in chemical plants show significant differences on heart disease.  In a collaboration of dairy producers, processors and health researchers, a butter enriched with CLA was produced and used in clinical trials. However, translating these benefits to the consumer has been difficult because chronic diseases like cancer do not show up for years, so it is hard to determine the success of the intervention. Showing prevention of a disease is very different from treating an existing disease. Proving prevention requires greater mechanistic understanding of how these different fat structures actually function in the body.  Once we understand the mechanisms of action, we can build our story of health.

An important point made at the meeting was that we need to sort out the great complexity of milk fat rather than just look at it as a homogeneous lump. The negative stigma associated with saturated fats overshadows appreciation of benefits derived from consuming unique milk fat components. No other fat in the human diet has the complexity anywhere near what milk fat has. Complex fats are important in the body and having a dietary source of them could positively impact health. Milk fat globules can be loosely divided into small and large particles. The small particles are exciting because they are enriched for membrane and complex fats. These small particles are abundant in milk, and their function in the newborn infant could be instrumental in developing skin, brain and intestinal tissues. Likely these attributes will see similar roles as we age.  The innovation here will come from finding novel mechanisms and assessment tools for looking at the effects of consuming small fat globules.
A clinical study on the impact of increasing whey protein in the diet on specific health conditions related to obesity and metabolic syndrome in women showed that a 5 to 10 percent decrease in weight can significantly improve fertility. Weight and fat mass loss was greater with increased protein compared to carbohydrates. As part of the study, women were tested immediately after a meal to show how their body responded to that meal. The immediate effects of food present an opportunity to develop health diagnostics that bring established bioactive ingredients to practice. Further studies could determine any unique bioactives in whey protein that contribute to the observed weight loss to differentiate it as a bioactive food. As milk is better characterized at the molecular and structural level, benefits to the consumer will be more easily identified. To be successful, these bioactive projects need the food science, nutrition and medical fields to come together to discuss these ingredients from their multiple perspectives.