Introduction
Nutrition research has traditionally focused on identifying the specific associations through which single nutrients impact health outcomes – for example, calcium and bone health, protein and skeletal muscle and, saturated fat and heart disease. The approach to studying individual nutrients in relation to health has been described as a ‘reductionist’ perspective (Messina et al.,2001).
However, the focus of nutrition research has shifted to examine the association of whole
foods and dietary patterns with health (Mozaffarian et al., 2018). This includes recognizing not only that foods have numerous nutritional attributes but also that the effect of one attribute is likely dependent on the combination of nutritional components contained in the whole food and the resulting structure. This focus shift is also based on the fact that people consume nutrients as part of a food, and not in isolation. In addition, foods are usually also eaten as part of a meal.
The dairy matrix
The term “dairy matrix” refers to the complex composition and structure of dairy products, particularly in relation to their nutritional and functional properties. The matrix refers to the overall arrangement and interactions of different components within the dairy product, including proteins, fats, carbohydrates, minerals, vitamins, and other bioactive compounds.
- Dairy matrix describes the unique structure of a dairy food, its components (eg nutrients and non-nutrients) and how they interact.
- Dairy matrix health effects refer to the impact of the whole dairy food on health that extends beyond its individual components (eg nutrients and non-nutrients).
The dairy matrix plays a crucial role in determining the digestion, absorption, and bioavailability of nutrients present in dairy products. The physical and chemical properties of the matrix can affect the release and availability of nutrients during digestion, as well as influence interactions with other dietary components.
For example, the proteins in the dairy matrix, such as casein and whey proteins, can form complex structures that affect their digestion and absorption rates.
These proteins can also interact with other nutrients, such as calcium, influencing their availability to the body. The fat globules in milk and dairy products are surrounded by a membrane that affects the digestion and absorption of fats and fat-soluble vitamins.
The dairy matrix can also have functional implications. It contributes to the texture, mouthfeel, and sensory attributes of dairy products. The matrix influences the stability and rheological properties of dairy-based products like cheese, yogurt, and ice cream, giving them their unique characteristics.
Impact of Whole Dairy Foods on Health
Dairy foods are unique with regard to their nutrient content and structures, both of which differ across the dairy food category. Dairy foods are excellent sources of calcium, vitamins B2 and B12, high-quality protein, iodine, and also rich in magnesium, potassium, and various fatty acids (FAO, 2013).
- Milk is an emulsion, which consists of droplets of fat suspended in an aqueous phase containing proteins and numerous vitamins and minerals.
- The composition and structure of cheese and yogurt can vary depending on the type of milk used and the method of production.
In 2017, an eminent group of researchers acknowledged that health effects of a food are much more complex than that of a single nutrient it contains or even a few nutrients owing to the food matrix.
Additionally, it is well-accepted the importance of dietary calcium for its significant contribution to bone health.
However, all calcium sources are not the same nor is the matrix in which it is contained. The health effects are a function of both the food’s structure and its composition, and how the components interact with each other (Thorning et al., 2017). The food matrix directly affects the process of digestion and absorption of food compounds in the gastrointestinal tract, affecting the overall nutritional and health effects of foods (Aguilera, 2019).
Nutrients and bacteria are important
Dairy foods are a rich source of vital nutrients, including protein, fat, and many vitamins and minerals. Fermented products such as yogurt and cheese contain bacteria and evidence suggests that these can help to boost the immune system and restore a healthy balance of bacteria in the gut.
Solid or liquid – physical structure matters
Yogurt (semisolid) and cheese (solid) stay in the gut for longer, slow digestion and suppress appetite when compared with milk (liquid). This affects the absorption of nutrients and their impact on the body.
Milk fat globules and reduced cholesterol absorption
Fat globules in milk are each surrounded by a membrane. High-fat dairy products, with the exception of butter, are rich in milk fat globule membrane (MFGM). Products with high MFGM, such as cheese, are associated with reduced cholesterol absorption.
Milk and dairy products are broadly recommended as part of healthy eating patterns (Geurts, 2022). Their key role in human nutrition, health and development throughout life is generally only attribute to their nutrient richness.
- Drouin-Chartier et al. (2016) conducted a systematic review of meta-analyses of prospective population studies on the association between dairy consumption and cardiovascular disease, coronary artery disease, stroke, hypertension, metabolic syndrome, and type 2 diabetes.
- The results showed that the consumption of various forms of dairy products has either favourable or neutral associations with CVD outcomes.
- This has recently been supported by other meta-analyses of cohort studies by Giosue et al. (2022) who showed that dairy consumption (up to 200 g/day, globally) has no detrimental effect on cardiovascular health and indicated that the effect on cardiovascular health appears to depend more on the food type (cheese, yogurt, milk) than on the fat content.
- A neutral association was found for milk, while fermented products—cheese and yogurt—were associated with a lower risk of total mortality and cardiovascular events (Giosuè et al., 2022).
Dairy matrix and health outcomes
The interactions within the dairy matrix can affect the release and bioavailability of nutrients and bioactive compounds during digestion. For instance, the presence of calcium and other minerals in dairy can influence the absorption of other nutrients. Additionally, the structure of proteins and fats in dairy can impact the digestion and absorption rates of different components.
People who regularly consume milk, yogurt and cheese are more likely to have reduced risks of colorectal cancer, high blood pressure, heart disease and stroke (Godos et al., 2020). Yogurt consumption has also been associated with protection against type 2 diabetes.
The positive effects of high-fat dairy products such as cheese on blood pressure and heart health may surprise you. It’s clear that the relationship depends on more than saturated fat or total fat content (Yu et al., 2018).
The dairy matrix also seems to play a role in the benefits of dairy on bone health. A study in rats has suggested that calcium from dairy foods is better than calcium supplements for bone growth. The effect wasn’t due to differences in calcium absorption.
Research on the dairy matrix explores how processing techniques, such as heat treatment or fermentation, can alter the composition and structure of dairy products, subsequently affecting their nutritional properties and potential health benefits.
Overall, understanding the science behind the dairy matrix helps researchers and nutritionists gain insights into the complexities of dairy products and their impact on human health, providing a foundation for evidence-based dietary recommendations and the development of functional dairy foods.
Lastly but by no means least, this is important in research and product development, as it helps scientists and food technologists optimize the composition and processing of dairy products to enhance their nutritional profile, functionality, and overall consumer experience.
References:
- Messina, M., Lampe, JW, Birt, DF, Appel, LJ, Pivonka, E., Berry, B., & Jacobs, DRJ (2001). Reductionism and the Narrowing Nutrition Perspective: Time for Reevaluation and Emphasis on Food Synergy. Journal of the American Dietetic Association, 101(12), 1416-1419. https://doi.org/10.1016/S0002-8223(01)00342-X
- Mozaffarian D. Dairy Foods, Obesity, and Metabolic Health: The role of the food matrix compared with single nutrients. Adv Nutr 2019; 10: 917S–923S.
- Muehlhoff et al. Milk and dairy products in human nutrition. Rome: Food and Agriculture Organisation of the United Nations; 2013. www.fao.org/docrep/018/i3396e/i3396e.pdf
- Thorning TK et al. Whole dairy matrix or single nutrients in assessment of health effects: current evidence and knowledge gaps. Am J Clin Nutr 2017: 105:1–13.
- Aguilera, JM (2019). The food matrix: implications in processing, nutrition and health .Critical Reviews Food Science and Nutrition, 59(22), 3612-3629. https://doi.org/10.1080/10408398.2018.1502743
- Geurts, J. (2022). The role of the dairy matrix in the contribution of milk and dairy products to the human diet. In. Burleigh Dodds Science Publishing Limited. https://doi.org/10.19103/as.2022.0099
- Drouin-Chartier, JP, Brassard, D., Tessier-Grenier, M., Côté, JA, Labonté, M. É., Desroches, S., Couture, P., & Lamarche, B. (2016). Systematic Review of the Association between Dairy Product Consumption and Risk of Cardiovascular-Related Clinical Outcomes. Advances in Nutrition, 7(6), 1026-1040. https://doi.org/10.3945/AN.115.011403
- Giosuè, A., Calabrese, I., Vitale, M., Riccardi, G., & Vaccaro, O. (2022). Consumption of Dairy Foods and Cardiovascular Disease: A Systematic Review. Nutrients, 14(4), 831. https://doi.org/10.3390/nu14040831
- Godos J, Tieri M, Ghelfi F, et al (2020). Dairy foods and health: an umbrella review of observational studies. Int J Food Sci Nutr.71:138–151 https://www.tandfonline.com/doi/abs/10.1080/09637486.2019.1625035?journalCode=iijf20
- Yu E, Hu FB(2018). Dairy products, dairy fatty acids, and the prevention of cardiometabolic disease: a review of recent evidence. Curr Atheroscler Rep.;20:24. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5990967/pdf/nihms970782.pdf
