SCIENCE FRIDAY: BENEFITS OF DAIRY

Yummy! Not what the post discusses. Taken by PKSenagore August 2017. All rights reserved.

THE QUESTION POSED in the title of Julie Stewart's excellent fitnessmagazine.com article, “Should You Give Up Dairy to Lose Weight?” has an answer that doesn’t require much thought, for those with nutrition knowledge. 

Without a medical reason, no.
 
Insert the name of any major food group* into that sentence and the answer will be the same. It’s not safe to assume that totally omitting all elements of a single major food group will be beneficial to health in the absence of a disease condition. 
 
Certainly, some individuals may wish to forego eating foods because of religious or social convictions. But to avoid the health consequences of that decision, nutrients that will be eliminated by such an action will need to be individually added by diet ‘work-arounds’ and supplements. However, the individual components of a food may not constitute the entirety of the benefit derived from eating that food.
 
Huh?
 
The macro-nutrients (carbohydrates, proteins, fats, fiber, water) and micronutrients (vitamins and minerals) that are contained within a food represent individual components. These nutritional components are combined within a “specific structural arrangement” or “food matrix”. It has been suggested that synergies can develop between nutrients arranged in a matrix, which can have a potentially beneficial or detrimental effect on the nutritional or biological value of that food. 
 
Canadian scientists, who have had research supported by a yogurt manufacturer, discuss the possibility that there is another layer of benefit, beyond nutrients within a matrix, to be gained from eating foods in combination. Specifically, eating yogurt and fruit in combination.
 
In the article “Potential Health Benefits of Combining Yogurt and Fruits Based on the Prebiotic and Probiotic Properties” M Hernandez and A Marete, from Laval University in Quebec make this case.   They explain that yogurt is an energy dense food that is a good source of high quality dairy protein, calcium, magnesium, Vitamin B-12, and key fatty acids; it is also a pro-biotic (contains ‘good’ bacteria that aid in nutrient digestion and absorption). And that fruits are an excellent source of anti-oxidants, and fiber; some fruits like grapes and berries are high in pre-biotic polyphenols that support the growth of probiotic ‘good’ bacteria.
 
These scientists propose that combining intake of the two at the same time could “exert synergistic effects on health”, related to their prebiotic and probiotic potential and known associations with lowered risk of cardiovascular disease (fruits), and with reduced weight gain and risk of type 2 diabetes (yogurt).
 
Evidence of how this might work, the researchers say, comes from an in-vitro study (not in a human or animal but in a lab experiment) that modeled digestion.  It demonstrated that when an anti-oxidant extract of green tea was added to a “dairy matrix” of milk, yogurt, or cheese, the integrity of polyphenols in the tea extract seemed to be protected, and the anti-oxidant activity enhanced. 

To increase the complexity of this discussion a bit more, the research paper also discusses how the eating of one food may positively influence the intake of other healthy nutrients.  Cereal is an easy-to understand example of this concept.  

The scientists indicate that in persons of both genders and across age groups in the USA, “ready–to-eat breakfast cereal consumption has been shown to be associated with higher milk and calcium intake.”  European adolescent cereal-eaters (12.5-17.5 years) likewise tend to have a “better diet quality index, higher micronutrient intake, more frequent fruit consumption, and more milk and yogurt consumption.”

To those who eat cereal this research is no big surprise. Cereal eating may be one the few instances in which we automatically search for milk in the refrigerator or reach for a banana or other fruit. However, the findings serve to alert us that “cutting” dairy could have unintended effects on our diet and ultimately on long term well-being.

Of course, persons with an allergy to milk proteins or a deficiency in the enzyme needed to break down milk sugars (lactose) will have medical reasons to avoid or limit certain dairy products. But the rest of us should seriously reconsider giving up eating milk-based products, if the purpose in doing so is to be ‘healthier’.

The take home messages tied to the featured article’s question and the research discussion:         1) Before deciding to eliminate an entire basic food group, in order to be generally healthier or to lose weight, recognize that this action might have other unhealthy consequences. Like the elimination of foods usually eaten in combination.

2) The ‘food matrix’ or structure of an eliminated food might be integral to its nutritional benefits, which may not be provided by a supplement.

3) Dairy food group items contain high quality protein that is convenient to obtain and consume, as needed, before and after high intensity workouts. Non-dairy substitutes are not replacements for these specific proteins.

4) The scientific reasons to eat yogurt and fruit in combination have been hypothesized but not yet fully studied.

5) Weight loss is accomplished by a calorie deficit. Eating a smaller volume of dairy items may be healthier than elimination.
 
6) Whether increased dairy intake plays a beneficial role in preventing long term gain in weight and waist circumference needs further study.
 
This topic has me cringing. My younger twenty-something-self decided to eliminate milk and most dairy to save calories as a weight-maintenance strategy. I figured supplements would suffice.

Reading scientific literature on the importance of protein generally and milk proteins specifically to overall health, and to muscle and bone, I realize I short-changed myself for many years. Learning what trainers and coaches recommend for runners and athletes of all sports, further reinforces that this was a mistake. However, I made changes for the better over the years.
 
The general rule and best advice, still, is to eat a balanced diet comprised mostly of whole (not processed) foods from all major groups. For those with ready access to such food and the ability to pay for it, it's relatively simple. For those who don't, that's another blog post topic.

Stewart's article answers the question a bit differently. It's well worth reading. 
 
RUN HAPPY!
 
*The 5 major food groups include: fruits, vegetable, grains, protein foods (meat, poultry, eggs seafood, nuts, seeds, and soy) and dairy. This post is not about vegetarians eliminating meat, etc.!.
 
https://www.usda.gov/media/blog/2017/09/26/back-basics-all-about-myplate-food-groups
 
https://www.fitnessmagazine.com/weight-loss/plans/diets/should-you-give-up-dairy/
 
https://www.nal.usda.gov/fnic/macronutrients
  
https://www.ncbi.nlm.nih.gov/pubmed/28096139
 
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3954432/ B carotene
 
https://www.healthline.com/nutrition/probiotics-and-prebiotics
 
https://chriskresser.com/do-polyphenols-improve-your-gut-bacteria/
 
https://www.nature.com/articles/ijo201378
 
https://breakingmuscle.com/healthy-eating/eat-to-perform-simple-dietary-advice-for-the-athlete
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