ditch dairy
I’ve heard it before, and have probably said it myself: “I could never give up cheese.” Personally, I loved cheese. It was the last thing I quit eating as I transitioned to a plant-based diet. It’s challenging to give up certain foods we like, not just because we enjoy the physical experience of consuming them, but because we’ve developed an addiction to them. We know that fat, sugar, and salt have drug-like addictive properties, and cheese is high in both saturated fat and salt. Other dairy products we consume often include two out of three of this trio: think ice cream, milk chocolate, flavored yogurts, and salted butter. It’s no wonder that dairy is difficult to let go of. There are compelling reasons to do so, though - and we should keep them in mind as we adopt a healthier diet.
acne
Consuming dairy exposes us to a variety of hormones such as estrogen and IGF-1, which may have potent biological effects, one of which is acne. Though some argue that the hormones in dairy aren’t present in biologically relevant quantities, its metabolic effects may still be sufficient to have an impact. The Harvard Nurses’ Study found that a positive association between consumption of total milk and skim milk and acne. It’s important to note that an association does not imply causation. However, the Journal of the American Academy of Dermatology posited: “The papers from the Harvard School of Public Health establish an association between milk consumption and acne. But how could milk cause acne? Because drinking milk and consuming dairy products from pregnant cows exposes us to the hormones produced by the cows’ pregnancy, hormones that we were not designed to consume during our teenage and adult years.” Furthermore, a recent 2018 meta-analysis of 14 studies found an increased odds ratio for acne in individuals aged 7-30 who consumed any dairy.
I struggled with acne as a teenager. At the time, I ate a poor diet that consisted of a lot of cheese and ice cream. I used face masks religiously, drank a lot of water, and applied spot treatments. Though these techniques helped temporarily, I would inevitably have another breakout. I felt like I was in a battle with my skin. Now, I don’t have a skincare routine beyond gentle washing and moisturizing, and I can’t remember the last time I had a pimple to deal with. This is my anecdotal experience, which shouldn’t be treated as scientific evidence, and a lot has changed in my diet besides cutting dairy consumption. However, I wanted to point out that superficial remedies like face masks don’t treat the cause. If you’re struggling with acne, it’s worth it to trial quitting dairy, which isn’t a necessary part of our diet.
cancer
The vast majority of our dietary exposure to hormones comes from dairy, including IGF-1. IGF-1 is a growth hormone that stimulates cell proliferation. It’s important for growth during childhood, but elevated levels in adulthood may promote tumor development. Epidemiological evidence suggests that cancer risk is related to levels of IGF-1, which may be a potential mechanism for the growth and development of hormone-sensitive cancers. Other factors continue to be investigated, like saturated fat, casein, and other hormones present in dairy, like prolactin, steroids, progesterone, and estrogen.
One of the most common cancers among men in the United States is prostate cancer. A meta-analysis of 11 studies found a positive association between milk consumption and prostate cancer, and a subsequent meta-analysis concluded that consumption of milk and dairy products may increase the risk of prostate cancer. Interestingly, Dr. Dean Ornish conducted a trial to study the effect of lifestyle therapy on prostate cancer among men who had refused conventional treatment. Treatment included a vegan, low-fat, plant-based diet, exercise, and meditation. The result? PSA (elevated levels of which may be indicative of cancer) levels dropped in the experimental group and increased in the control group. I cannot point to omission of dairy as the cause of this result because multiple lifestyle changes were made, but it’s worth noting that a diet change was the cornerstone of this intervention.
Finally, a study conducted by Harvard School of Public Health found a significant association between dairy intake and endometrial cancer. Wrote the authors: “Estrogens have a central role in the etiology of endometrial cancer. Milk and dairy products are a source of steroid hormones and growth factors that might have physiological effects in humans.” Remember that commercial milk is produced from pregnant cows, increasing its estrogen levels.
nutrient-blocking effects
One powerful reason not to eat dairy? It may block the beneficial effects of phytonutrients. Do you enjoy your tea with milk or cream? Consider this study which concluded that milk counteracts the favorable effects of tea on vascular function. Black tea improves the ability of your blood vessels to dilate, but the addition of milk “completely blunted the effects.”
Furthermore, we know that berries contain powerful antioxidants. Another study found that volunteers who had blueberries with water saw a boost in their antioxidant levels, which is to be expected. However, those who consumed blueberries together with milk did not enjoy an increase in their antioxidant levels, demonstrating that the addition of milk impaired the antioxidant properties of the berries.
If you’re loading up on phytonutrient- and antioxidant-rich foods but pair them with dairy products, you may not be reaping the benefits. This is one powerful reason to limit your consumption of dairy: it could reduce the efficacy of an otherwise healthy diet.
benefits of dairy?
What about bone health, calcium, and vitamin D? Dairy has long been touted as essential for strong bones because it is high in calcium. We know that bones are your body’s reservoir for calcium, and if you don’t have enough, your body will strip calcium from your bones to compensate, making them less dense and more prone to breakage. However, the link between the calcium you consume and the strength of your bones is unclear. Your bones are alive and respond to a variety of factors, one of which is weight-bearing physical activity. Researchers found that, according to meta-analyses, there was no association between calcium intake and hip fracture risk in men and women. Another study compared the bone density of lifelong vegan and omnivorous women, which found no significant correlation between dietary calcium and bone density. In other words, though the vegans had lower intakes of dietary calcium, this did not have an adverse effect on their bones. Finally, though teenagers and young adults are in their prime bone-building years, a 2014 study concluded that greater milk consumption during teenage years was not associated with lower risk of hip fracture in adulthood.
What about vitamin D? Vitamin D boosts the absorption of calcium, so pairing them together is important. Dairy is fortified with vitamin D, which means vitamin D is added to it; vitamin D is not naturally present in dairy. Sun exposure remains the most reliable way for our bodies to synthesize their own vitamin D. I elaborate on this in my piece about safe sun exposure.
Of course, though we are still unsure of how much calcium intake is adequate to reduce the amount your body has to borrow from bone, calcium consumption is important. Calcium has a variety of critical roles in our bodies! There are plenty of plant sources of calcium, like dark, leafy greens, legumes, figs, and soy. Vitamin K is mainly found in leafy greens, low levels of which have been linked with low bone density. In fact, the Nurses’ Health Study found that one serving of lettuce per day (or other green, leafy veggie) cut the risk of hip fracture in half. Between dairy and greens, my vote goes to greens - after all, they are the most nutrient dense food.
Want to build your bones? Boost your weight-bearing activity and strengthen your muscles, get safe sun exposure, and eat plant foods high in calcium.
final thoughts
I often hear that nutrition is “confusing” because the science is “always changing.” The waters are certainly muddied by the fact that controlled, long-term nutritional studies are nearly impossible to conduct, and we often must rely on observational, epidemiological studies. Self-reporting introduces a source of bias. Further complicating matters is the influence of industry on nutritional studies; I’m wary of industry-funded science. Marion Nestle examines industry’s impact on nutritional guidelines in her book Food Politics, which I am currently reading and recommend you delve into if you want to know more.
Despite this, we continue to peel back the layers of what we should be eating for optimal health. In my experience, leaving dairy behind has left me with clearer skin and better energy levels. My blood work this year revealed the healthiest numbers I’ve ever had. If you’re on the fence, consider dropping dairy to see what kind of impact it has on your life. You may be surprised.
