The science behind dairy studies isn’t necessarily wrong, but it is flawed in that the methodology is built to garner a specific outcome—an outcome that will help the industry to market dairy.
Countless dairy studies have surfaced by the media and lobbying
efforts that claim cow’s milk benefits athletic performance and
overall health unlike any other food or beverage. These headlines
assure readers that dairy is the key to unlocking athletic potential
or helping you lose those five stubborn pounds. What these authors
and marketing advertisements do not say is that they only skimmed
the abstract of the study. This is how glaring misinformation gets
spread. Our Switch4Good scientists and medical professionals have
reviewed hundreds of dairy studies, and they have found a common
trend: the studies are designed to favor a positive dairy outcome.
Of course, that isn’t mentioned in the abstract. The next time you
come across an article that states yogurt will calm your gut or
chocolate milk will help you recover, keep these seminal details in
mind.
Dairy Studies Make Assumptions, Not Conclusions
Many dairy studies set out to prove that dairy is better than an
alternative option. For example, the industry claims that dairy is
more hydrating than water. This angle is used to market liquid dairy
products to athletes. In this specific study conducted in 2016, the
researchers oversimplified the science of hydration and made their
conclusion based on assumption. Technically, the study participants
retained more fluid in their bodies after consuming dairy in
comparison to water, but the researchers were unable to determine if
that fluid was water or some other substance. In terms of hydration,
water is the only marker that matters, because hydration is measured
by the amount of water in the body, not overall fluid. In essence,
the study proved that dairy encourages more fluid retention. Other
studies have referenced this paper to explain why the researchers
were led to this conclusion. According to this 2019 study, the
sodium content of cow’s milk triggers more fluid retention than
water, which does not contain sodium. However, fluid retention is
not necessarily a benefit. The body works best when a healthy flow
of fluid is maintained and not inhibited. When this flow is slowed
and the body retains excess fluid, a person may experience bloat and
constipation. Of course, the dairy studies won’t document these
uncomfortable side effects—they’ll just tell you how much more
“hydrating” milk is than water.
Dairy Studies Compare Apples to Oranges
Dairy studies that tout cow’s milk as the optimal performance
beverage always compare it against another beverage during the
testing phase. In a fair fight, dairy would be compared with a
macronutrient-matched (IE the same amounts of carbohydrate, protein,
and fat) beverage such as soy or pea milk. However, industry-funded
studies are designed to favor dairy; therefore dairy is most often
compared to nutritionally inferior beverages such as water or an
“isoenergetic carbohydrate placebo” which is essentially sugar
water.
Switch4Good has reviewed several studies that use this
apples-to-oranges comparison. For example, a 2015 study of
professional judo athletes compared the recovery and performance
effects of chocolate milk versus water. Chocolate milk outperformed
water, which is no surprise, because at the very least, it contains
calories. Athletes need to refuel after hard training; therefore, a
substance with any nutritional value will outperform water which is
completely devoid of calories and nutrients. Another 2015 study on
the performance effects of chocolate milk also used water as the
control, this time with rock climbers. Again, athletes displayed
improved results when drinking chocolate milk simply because they
were consuming some form of carbohydrate and protein—two nutrients
that are not unique to dairy.
Even in studies that compare cow’s milk to sports drinks, it’s
typically an isocaloric substitution, meaning the participants
consume the same amount of calories, but the nutrient similarities
end there. A 2019 study with adolescent athletes compared chocolate
milk to a protein-free carbohydrate sports drink. While the
carbohydrate intake matched across both conditions, the sports drink
was inferior in terms of protein and calorie content—both of which
are essential to athletic recovery. Again, chocolate milk
outperformed the competitor, but this study did not prove that
chocolate milk is an optimum sports drink; it only confirmed what we
already know—all three macronutrients (carbohydrates, fat, and
protein) are needed to optimize recovery and performance.
Respected research entities have recognized these flawed
methodologies in studies touting dairy as a performance enhancer.
The esteemed Canadian Clinical Practice Guidelines for Diabetics
specifically notes that dairy-based studies capitalize on using an
unfair comparator. These guidelines also state that “systematic
reviews and meta-analyses of randomized controlled trials of the
effect of diets rich in either low- or full-fat dairy products have
not shown any clear advantages for body weight, body fat, waist
circumference, fasting blood sugar, or blood pressure across
individuals with different metabolic phenotypes (otherwise healthy,
with overweight or obesity, or metabolic syndrome).”
In a systematic review titled “Impact of Cow’s Milk Intake on
Exercise Performance and Recovery of Muscle Function” that was
published in the Journal of the International Society of Sports
Nutrition, researchers concluded, “More and better study designs
such as blinding the beverage to both, participants and personnel,
generate a random sequence of beverage group, etc. are needed to
demonstrate its usefulness as a sport nutrition-related supplement.”
The authors also write, “Based on the current evidence, it cannot be
determined whether cow’s milk has a positive effect on exercise
performance and recovery of muscle function in humans.” The science
behind dairy studies isn’t necessarily wrong, but it is flawed in
that the methodology is built to garner a specific outcome—an
outcome that will help the industry market dairy.
Read the Study, Not the Headline
Most of us don’t have time or desire to analyze scientific
literature, and we rely on headlines to consume our news. At
Switch4Good, we work with scientists to understand and interpret
dairy-related research to paint a more complete picture so you can
make informed decisions about what goes into your body. In the end,
ethical science—not twisted research—will always prevail.