The words “fermented” and “dairy” have strong links to nutrition and health that have stood the test of time. But like many foods, we continue to discover nutritional properties found in fermented dairy products that benefit our health throughout life. A quick review of the history of fermented dairy products and some of the better-known health benefits provides a basis for some new, cutting-edge research. 

Nutritional history

Fermented dairy products have existed since before 7,000 BC, when fermentation happened through naturally occurring bacteria in milk stored in warm climates, which served to preserve milk so it could be consumed over a longer time period. Many populations, especially in the Middle East, Mediterranean, and South Asia, consumed fermented dairy products on a daily basis.  

It wasn’t until the early 1900s that Nobel laureate Elie Metchnikoff at the Pasteur Institute in Paris published an article, “The Prolongation of Life,” which proposed the scientific rationale for the health benefits of yogurt bacteria. His hypothesis was S. thermophilus and L. delbrueckii ssp. bulgaricus controlled the infections caused by enteric pathogens and regulated toxemia, which improved aging and mortality in Bulgarian peasants. 

It was later discovered that neither microorganism survived through the intestinal track but that L. acidophilus did survive the infant gastrointestinal (GI) track. The ability of a microorganism, like L. acidophilus, to implant in the colon and grow helps to classify it as probiotic. Many researchers have since identified specific probiotic strains of bacteria that have documented health benefits, many of which are used in fermented dairy products today. 

Digestion benefits

The 100 trillion bacteria that live in balance in our colon (our microbiome), function in healthy individuals to reduce blood lipids, modulate cell growth and differentiation, fight pathogens and other infections, provide immune stimulation of gut-associated lymphoid tissue, and synthesis of vitamins. In times of stress, increasing age, GI distress, and/or antibiotic treatment, this balance is negatively impacted. Restoring the colon is possible through consumption of fermented dairy products containing probiotics. Recent research has found that yogurt starter bacteria, such as L. delbrueckii ssp. Bulgaricus, produce broad-spectrum antibacterial agents, called bacteriocins, which inhibit contaminant pathogenic bacteria. 

The high buffering capacity of milk proteins also helps keep yogurt cultures viable through the intestinal track, which is a benefit for lactose intolerance because the cultures will aid in hydrolysis of any remaining lactose consumed with the yogurt. Yogurt is easier to digest than milk because of the action of cultures on lactose digestion and the fact that the whey proteins are denatured in the high temperature pasteurization conditions, making them less allergenic. The cultures also produce proteases during the fermentation process, which hydrolyze the caseins and whey proteins prior to consumption, which also aids in digestion. 

Disease prevention

When it comes to addressing diseases, earlier this year, the FDA approved the use of the qualified health claim that consumption of two cups of yogurt per week may reduce the risk of Type 2 diabetes. This health claim does not mean that yogurt consumption will prevent Type 2 diabetes, but reducing risk is always a good thing. Studies with probiotic-containing yogurts have also been effective for treatment of diarrhea, irritable bowel disease, nonalcoholic fatty liver disease, cardiometabolic disease, serum cholesterol and blood pressure.

Bifidobacterium and Lactobacillus, especially L. acidophilus yogurt cultures, have also been shown to have anticarcinogenic properties, which are active against certain tumors found in colon cancer. Even though much of the evidence we have developed on fermented dairy foods has focused on the presence of live and active cultures, we have the nutrient density of dairy foods to factor in as well. 

Nutritional density

According to the National Dairy Council, yogurt provides seven essential nutrients to the diet, including protein, calcium, phosphorus, Vitamin B12, pantothenic acid, riboflavin, and zinc. Given the high protein quality of dairy proteins with both caseins and whey proteins present in yogurt, and the range of protein levels available on the market, it is easy to find up to 20g of dairy protein in one serving (5.3-oz.) of yogurt. Though protein is often associated with muscle growth and repair, it is also essential for bone growth and development along with calcium, phosphorus and magnesium. Both calcium and phosphorus also contribute to the growth of healthy teeth. Casein also coats the teeth and protects the enamel from acids consumed in other foods.  

Yogurt consumption is associated with a reduced risk of weight gain and obesity, somewhat due to its nutrient density. It has also been found to have anti-inflammatory properties. Some inflammation in the body is good because it is how our immune systems react to being attacked by an organism like a virus. 

Chronic inflammation is also believed to be responsible for conditions like eczema, psoriasis, arthritis and more. Yogurt is thought to reduce inflammation by improving the integrity of the intestinal lining, which prevents endotoxins produced by gut bacteria from crossing into the bloodstream and causing inflammation. Studies that have focused on these anti-inflammatory properties have yet to find out what is in yogurt that provides that benefit.  

In much of the positive research associated with regular yogurt consumption, it isn’t clear which specific compounds in yogurt deliver the health benefits. Much of the research discusses bioactive compounds such as bioactive peptides that are the byproducts of fermentation.  

The yogurt matrix is complex, and commercial yogurts use different strains of yogurt cultures, often have added probiotics, and vary in their processing conditions and storage time, which makes it difficult to quantify and characterize all the potential byproducts of fermentation. As we do more research on fermented dairy products, we hope to discover more about these bioactive compounds and their benefits to human health. Continued funding for dairy foods’ research will be key to untapping more health benefits for consumers.