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.