By Melissa Furneaux, B.Sc., HHC, RHN
Most of us have grown up with the firm belief that milk is an important part of a balanced diet, and absolutely necessary for strong bones and teeth. This idea is so ingrained in our culture that most of us do not so much as question it; it is common thought that if we want to avoid osteoporosis in our later years, we need to drink hefty amounts of dairy now. But is this really the case? Like so many nutritional controversies, it turns out that this situation is rather complicated. So let’s begin with the basics…what exactly is calcium, and what does it do in the body?
Calcium is a macro-mineral, and it is also the most abundant mineral in our bodies, accounting for about 1.5-2% of our body weight. Almost all of it, around 98%, is in our bones; another 1% is in our teeth, and the final percent is in and around our cells. While calcium is certainly best known for its role in bone health, it is actually involved in many functions throughout the body, including muscle contraction and heart regulation, nerve conduction, cell communication, blood clotting, and enzyme regulation, just to name a few. There’s no denying that we need adequate amounts of calcium to stay healthy. However, is the commonly recommended 2-4 servings of dairy each day an appropriate guideline?
Without going into detail, let’s just say that the influence of the dairy industry is far-reaching, its pockets vast, and their advertisements psychologically brilliant. The “Got Milk“ campaign, for example, is one of the most successful, long-running advertising campaigns of all time. If we step back from the politics, however, and take a look at the science, we can see that it is quite well-documented that greater dietary calcium intake does not correlate with stronger bones. On the contrary, if we look at global dietary consumption of dairy, we will find an inverse relationship between osteoporosis and dairy consumption. Yes, you read that correctly…as a general rule, the nations that drink the most milk also have the highest rates of osteoporosis. In addition, researchers have consistently found a direct correlation between animal protein intake and loss of bone mass. While we must be cautious to not make any conclusions based on this correlation alone, it does suggest that perhaps there is more to bone health than meets the eye.
As with all nutrients, it is not simply a matter of how much calcium you have in the body, but rather what your body is able to do with it. We know that our society isn’t lacking in calcium. So how can these counter-intuitive facts be explained? It seems that what we have is not a problem of calcium deficiency, but one of calcium absorption. The human body is complicated and dynamic, with systems and substances working synergistically…nothing occurs in isolation. Our bodies are constantly trying to maintain stable levels of calcium in the blood. If our bodies become too acidic, due to excess animal protein, stress, a high intake of carbonated soft drinks, or any variety of other reasons, calcium will be leached from our bones to help buffer acidity in the rest of the body. In effect our bones act as somewhat of a “mineral bank.”
There are many diet and lifestyle factors that either promote or inhibit calcium absorption, and unfortunately when it comes to the so-called “Standard American Diet, the scales are definitely tipped against us. A few common substances that interfere with absorption include: caffeine, soft drinks, diuretics, excessive meat/protein consumption, refined sugar and concentrated sweeteners, alcohol, cigarettes, other intoxicants, and excess salt. Many of these substances are high in phosphoric acid, or other acidic substances that create imbalance in the body. In addition to these substances that hinder absorption, there are other factors that must be present for absorption to take place at all. Most notably, these include vitamin D, magnesium, healthy parathyroid hormone functioning, and another hormone called calcitonin. The situation is even further complicated by the fact that vitamin D is a fat-soluble nutrient, meaning that the calcium in fat-free products is more difficult to absorb.
I am commonly asked “If I give up milk, where will I get my calcium from? As it turns out, there is a huge variety of non-dairy sources available, primarily our “beans and greens.” Many leafy greens are excellent sources, particularly kale, mustard greens, and bok choy. There are a few greens, such spinach and collards, that while being excellent sources of calcium, should be cooked to increase calcium bioavailability (due to the presence of oxalic acid). Many legumes are also excellent sources, including soy beans, tofu, adzuki beans, peas, and pinto beans. Sea vegetables, such as hijiki, nori, kombu, wakame, and kelp are also excellent sources. Other foods that contain calcium include brazil nuts, almonds, hazelnuts, bones (either eaten directly or used to make soup broths), and some dried fruits such as apricots. Many people choose to supplement their diet with calcium, although in my opinion this is somewhat missing the mark, again focusing on quantity over quality.
In the end, it is safe to say that this issue is complicated, and that the debate over milks purported health benefits and consequences will likely not be ending anytime soon. While milk is an excellent source of calcium, it is becoming increasing clear that their are a number of potential problems associated with milk and dairy intake as well…we have not even touched on the fact that approximately 70% of the world is lactose intolerant, that it is one of the most common dietary allergens in North America, and that it is not appropriate for many people due to ethical or religious reasons. Ultimately, however, it comes down to personal choice. If you choose to include milk in your diet, try to buy local and organic, if possible, as the quality of the product will be much better, and you will also be supporting more sustainable farming methods in your community.