Milk is a good source of calcium and vitamin D (though, remember, milk in the US contains vitamin D because it is mandated by law; in many other countries, milk is devoid of the sunshine vitamin), but it lacks many other nutrients crucial for healthy bones.
Too often, conversations and debates on the nutritional “worth” of milk turn into a “cows” versus “soybeans” face-off or, if it’s slightly more advanced, “cows” versus all the available milk alternatives (soy, almond, coconut, hemp, oat, and hazelnut).
As far as calcium is concerned, fortified foods and beverages contain calcium that is just as absorbable as — and in some cases, more absorbable than — the calcium in milk. In other words — the added calcium in soy or almond milk is just as good for your bones as the one in cow’s milk (or any other animal’s milk, for that matter).
In order to truly tackle the topic of bone health, though, we need to go beyond the calcium and vitamin D content of milk and its vegan analogues and instead identify all the nutrients that play important roles in bone health. In doing so, we find that milk is far from the king of the bone health hill.
Let’s begin with the vitamins:
1. Vitamin K has been shown to increase bone mineral density and lower osteoporotic fracture rates. It plays a crucial role in the activation of a protein called osteocalcin, which is necessary for bone formation. Vitamin K also regulates calcitonin, a protein that locks calcium in the bone matrix, thereby making it more difficult for cells known as osteoclasts from breaking down calcium. The best sources of vitamin K include kale, spinach, beet greens, chard, broccoli, mustard greens, and collards. In a neat twist, kale, broccoli, mustard greens, and beet greens are also excellent sources of calcium. This unique calcium-vitamin K punch gives dark, leafy green vegetables double the bone health power. Milk offers trace amounts of vitamin K (less than 0.5% of the Daily Value)
2. Vitamin C is usually in the news for immunity purposes (every “cold and flu season” you are bound to see an article titled “Can Vitamin C Cure Your Cold?”), but its supporting role in bone health is rarely discussed. Vitamin C is required to form collagen, a substance that helps strengthen bone. Additionally, new research conducted at Tufts’ Jean Mayer USDA Human Nutrition Research Center on Aging theorizes that “Vitamin C is capable of reducing oxidative stress and therefore may… inhibit bone resorption” and “protects against inflammation, which contributes to bone loss, and points to a strong association between vitamin C intake and bone density.” Vitamin C is found in many fruits and vegetables (including the dark green vegetables that offer calcium and vitamin K). Milk does not contain vitamin C.
Now, let’s take a look at some minerals:
3. Magnesium is another mineral important for bone health, and disturbingly, research shows that almost 70 percent of American adults consume less than the recommended daily allowance. Magnesium is needed for calcium metabolism and bone mineral density maintenance. While a cup of milk offers 7% of the daily value of this mineral, other foods — like almonds, cashews, oatmeal, and potatoes — offer higher amounts.
4. Boron is a trace mineral that never enjoyed 15 minutes in the trend spotlight, but is also a key player in bone health. While not an essential nutrient, small studies in the 1980s and 1990s have shown its importance in calcium metabolism, as well as its role in bone strength. Nuts and dark leafy green vegetables are the best sources of boron (chia seeds offer both calcium and boron!). Milk does not contain boron.
5. There is also manganese, which plays a key role in the formation of the bone matrix and is also a co-factor for a number of enzymes located in bone tissues. Best sources of manganese include pecans, brown rice, oats, pineapple, and spinach. Milk does not contain manganese.
6. Nutrition extends far beyond vitamins and minerals. Plant foods — and only plant foods — offer a wide array of antioxidants, phytonutrients, and flavonoids, some of which confer health benefits for our bones.
Studies have shown that catechins, for instance, are associated with increases in bone mineral density. One study that looked into food sources and bioavailability of polyphenols discovered that catechins are abundant in cocoa, beans, apricots, cherries, green and black teas, and apples. Milk does not offer catechins (or any phytonutrients, for that matter).
No one can argue that milk is not a good source of calcium; however, we need to break out of the pervasive paradigm that attaches a single nutrient to an entire health condition. Calcium plays a crucial role in bone healthy yes, but many other vitamins, minerals, and plant-based compounds are also necessary.
When you consider the vast array of nutrients required for optimal bone health, it becomes clear that while milk offers a few benefits, it is far from the perfect and complete beverage the dairy industry aggressively markets.