The puzzle of why yogurt seems to be even better for us than we’d expect from its nutrient content alone was the focus of the 6th global summit on the health effects of yogurt, “Yogurt, more than the sum of its parts”, held during the American Society for Nutrition 2018 conference in Boston.
Here experts from around the world gathered to discuss the unique properties of yogurt that could underly its health benefits. Topics included the role of the matrix of yogurt – all its different components – versus its single nutrients in health.
In their recently published report of the Summit, the authors explain that dairy foods come in three main types of matrix:
- Liquid – milk, some fermented milks
- Semi-solid – yogurt, some cheeses
- Solid – cheeses
The health effects of dairy products can vary according to their matrix, even when they have similar nutrient content, delegates at the Summit heard.
What is the matrix and what does it do?
Yogurt is densely packed with nutrients and is a great source of protein and calcium as well as a host of other vitamins and minerals. It can provide several shortfall nutrients and is associated with improved diet quality for both adults and children.
But a growing body of evidence suggests that yogurt and other fermented dairy foods are associated with a range of health benefits that can’t all be explained by their nutrient profile. Such benefits may include reducing our risk of heart disease and type 2 diabetes – and helping us maintain a healthy weight.
Now scientists reviewing research believe they’ve hit upon the explanation. It comes with the realisation that the nutritional and health value of a food depends on all its parts, not just the nutrients it contains. This ‘food matrix’ is a complex mix of components that interact with each other in a way that can affect how digestible the nutrients are and how well they can be taken up into the bloodstream.
The matrix of yogurt includes helpful bacteria
In the case of yogurt, the matrix also includes live bacteria and their products of fermentation that are thought to contribute to its health benefits.
As a fermented dairy food, yogurt contains two strains of live bacteria, Lactobacillus delbrueckii subsp bulgaricus and Streptococcus thermophilus, and further bacteria may be added during manufacture to increase the probiotic effect.
Thanks to these bacteria, eating yogurt and other fermented foods has been shown to modify our gut microbiome – the community of microbes that live in our gut and that are known to have a profound influence on our health.
The fermentation process also generates peptides from the proteins in dairy food, the authors point out. These biologically-active peptides may affect our blood vessels, immune system, nervous system, and hormonal system, research suggests.
It’s these effects that scientists believe may underly some of the health benefits of yogurt such as reduced risk of obesity, heart disease, stroke and type 2 diabetes. See more in this report from the Summit.
In this way, the matrix of yogurt sets it apart from non-fermented dairy products and this explains why the health benefits of yogurt seem to be greater than the sum of its individual parts – its nutrients, live microbes, and fermentation products.
‘The unique matrix of yogurt relative to non-fermented dairy products including the presence of live bacteria and their fermentation products, including bioactive peptides, are thought to play a role in the health benefits associated with yogurt consumption’ – Donovan SM, Goulet O, 2019.
Dietary guidelines should look at the whole food matrix
As described in our previous post, experts at the Summit called for updated dietary recommendations to focus on the food matrix rather than the individual nutrients they contain.
Many guidelines today tend to steer people towards choosing reduced fat versions of dairy products as a way of curbing their intake of saturated fat. But current research calls into question the assumption that saturated fats are always the villain in our diet.
Not all food sources of saturated fats behave the same way. For example, saturated fat in the dairy matrix seems to have different health effects from saturated fat in meat, say the authors. Dietary recommendations should therefore take account of the source of saturated fat. Indeed, it’s short-sighted to pick on one nutrient such as saturated fat and blame it for damaging our health say the authors.
The good news is that if you eat dairy foods, the chances are you’ll have a reduced risk of heart disease, stroke and type 2 diabetes, regardless of whether you choose low- or high-fat options
The authors conclude that recommending fermented dairy products in dietary guidelines could help improve public health thanks to the live bacteria and fermentation products they contain as well as their nutrient content.