As athletes, most of us know that calcium is important for bones but for many of us, that’s about where our bone mineral savvy ends. What you may not realize is blood calcium is very tightly regulated at 1% which means when dietary calcium is inadequate your body starts breaking down bone, the storage sight of calcium, to compensate. After adolescence, 1000mg/day is usually enough to maintain healthy bones, teeth, nerve function and muscle contraction but when it comes to absorption, there are a few other factors to consider for maximum efficiency.
For example, alcohol reduces calcium absorbition and inhibits the activation of vitamin D. Carbonated beverages have also been associated with reduced bones mass because of their high phosphorous content. In addition, excess sodium cause increased excretion of calcium in the urine. Some natural occurring plant toxins, like oxalic and phytic acids found in spinach, collard greens, sweet potatoes and beans, can also bind to calcium so it is best not to take supplements with these foods.
You typically absorb 30% of calcium found in food. Good sources include dairy products, greens, almonds, tofu and molasses with smaller amounts occurring in many fruits, vegetables, nuts, beans and grains. However, for athletes, especially female athletes or those unable to digest dairy, a supplement is a good idea. Nonetheless, the array of supplements is overwhelming. So what should you be looking for?
First of all, there are two major forms of calcium: carbonate and citrate. Citrate absorbs better (you can take it without food) and does not cause GI discomfort. However, the percentage is smaller so you’ll be popping about five pills a day and it’s generally more expensive. Pills should be taken with low iron meals in doses less than 500mg.
Next on the list is vitamin D which is essential for absorption. You want vitamin D3 and the RDA is 600mg. Very few foods (cod liver oil, eggs, fish) contain vitamin D so this is especially important during the winter months when the sun is too far to stimulate your skin to produce adequate levels of this vitamin.
Magnesium is also paramount for calcium storage. Apricots, bananas, avocados, whole grains, nuts and green leafy vegetables are all good sources of magnesium so if you’re eating whole foods, you should be set. However, if you find yourself relying on supplements to fill in your nutritional gaps, you should add this mineral to your list of things to look for in a calcium pill. Research has shown that magnesium citrate is superior to magnesium oxide and the RDA is 400mg.
Other cofactors for strong bones include boron and vitamin K but these are often found in adequate levels in the diet. In summary, while exercise is good for building up bone strength, intense training can cause increased risk of fracture and hormonal changes that decrease bone density. Since peak bone density is achieved in your early 20s, calcium is vital to maintaining optimal performance.