Let's Talk Common Sense Nutrition: Calcium and Bones..

Calcium and Bones

Physical Health Sciences & Sports Nutrition

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Calcium is one nutrient that's likely to he in short supply in bodybuilding diets. This is particularly true for those who don't consume dairy products, the most reliable food source of calcium. A recently published study that tracked the food intake of elite competitive bodybuilders found that the women averaged an intake of 52 percent of the Recommended Dietary Allowance (TWA) of calcium.

In addition, there's a nutritional controversy about the effects of a high-protein diet on calcium balance in the body. For example, according to another recent study, a high intake of sulfur-containing amino acids, specifically L-methionine and L-cysteine, causes the kidneys to excrete excessive amounts of calcium. One suggested antidote to counteract this effect involves ingesting a 16-to-I ratio of calcium to protein, or about 1,000 milligrams of calcium for each 60 grams of protein you eat.

Other studies downplay the negative effect of protein on calcium by pointing out that most foods that are high in protein are also high in phosphate. The significance is that phosphate, when consumed with protein, stops the calcium excretion from the body. Foods that are high in both protein and phosphate include red meat and milk. Studies show that eating these foods doesn't promote excessive calcium excretion.

Calcium, a silver-white metallic element, is the most abundant mineral in the body, making up about 2 percent of your bodyweight. Calcium is almost synonymous with hone, and sure enough 99 percent of the body's stores reside in bone. The remaining 1 percent, however, which circulates in the blood, performs many vital functions. For example, calcium ions found in muscle are vital to muscular contraction. The mineral also plays important roles in nerve transmission, blood clotting and both the synthesis and breakdown of liver and muscle glycogen.

These vital functions cause the body to continually monitor its blood calcium level. If it gets too low, the body will extract calcium from bone. This can lead to degenerative bone diseases, such as osteomalacia, a softening of the bones, and osteoporosis, a thinning of the bones that affects 24 million Americans, mostly women.


The RDA for calcium for adults is set at 800 milligrams. Young people between the ages of 11 and 25 need at least 1,200 milligrams daily because this is the period of most rapid bone growth. Recent studies suggest that degenerative bone diseases, such as osteoporosis, occur over a long term, starting at age 30 in most women. If a woman begins increasing her calcium intake as a teenager, studies show, she'll build a stronger bone foundation for later years. As that same woman reaches age 45, her calcium intake should increase to at least 1,500 milligrams daily.

After 45 a woman's estrogen production starts to decline, and estrogen helps to absorb arid retain calcium in the body. Women are at greater risk for osteoporosis because of their lighter bone mass. Weight-bearing exercise, such as weight-training, also helps the body retain calcium in bone.

Bodybuilders who eschew dairy products think they get enough calcium from other food sources, such as vegetables. While a few vegetables, like broccoli, kale and turnip greens, do contain calcium, the amount is considerably less than what you get from a dairy product, such as skim milk. One glass of skim milk contains 300 milligrams of calcium, while a half cup of fresh broccoli contains 89 milligrams. Other food factors affect calcium absorption. For example, the body needs vitamin D for the intestinal absorption of the mineral.

Researchers also suggest keeping a calcium-phosphorus ratio of 1-to-i because coo little phosphorus impedes calcium uptake and too much causes calcium excretion. Diet cola, a favorite beverage of many bodybuilders, is high in phosphorus but contains no calcium. You should also ingest about half as much magnesium as you do calcium. Magnesium keeps calcium in solution, preventing excess calcium deposits, such as kidney stones. Large amounts of caffeine inhibit calcium absorption, as do compounds in whole grains called phytates. Oxalates in green vegetables were once thought to inhibit calcium metabolism, but this was disproved by the fact that most vegetarian diets have an adequate calcium balance.

Besides being vital for the prevention of various bone diseases, calcium provides other preventive health benefits, according to recent research. For instance, studies show that it may have positive effects in lowering high blood pressure, particularly in people who produce low levels of a kidney substance called renin. Renin starts a biochemical cascade that leads to excessive sodium retention, which is a factor in high blood pressure. Few bodybuilders are aware that calcium also promotes sodium excretion, making it a natural diuretic.

Bodybuilders who resort to using pharmaceutical diuretics, such as Lasix, will lose calcium, magnesium, sodium and potassium. This loss of vital electrolytes explains the possible and often common side effects associated with diuretics, such as muscle cramps and heart rhythm disturbances. Other research shows that calcium may help prevent colon cancer, the second most common form of cancer in the United States. It does this through at least three mechanisms: 1) It speeds the excretion of bile acids, known colon carcinogens; 2) it binds to dietary fat, also speeding excretion; and 3) it slows the replication process in the cells lining the colon. Sometimes, it causes precancerous cells to revert to normal.

Another recent study shows that calcium may also help prevent cardiovascular disease. This study found that when men who had elevated blood cholesterol levels consumed 2,200 milligrams of calcium daily, their cholesterol decreased by 6 percent in nine to 11 days. The mechanism involved the formation of insoluble soaps consisting of calcium and ingested fat. The fat elimination doubled within 72 hours of calcium supplementation. The lack of calcium in typical bodybuilding diets is easily solved through supplementation. For best results also include the nutritional cofactors needed for calcium retention and absorption, such as vitamin D and magnesium. It isn't necessary to supplement with phosphorus, since that mineral is found in most high-protein foods.

Divide your doses of calcium each day. Studies show greater absorption rates if you take smaller amounts (400 milligrams or less) two to three times a day rather than one large dose. If you take in 800 milligrams of calcium, your body will absorb 300 milligrams, or 40 percent the other 500 milligrams is excreted out of the body. If you've been taking in less than optimum amounts of calcium, your body will absorb more. One reason for the high calcium absorption from milk is that milk contains a sugar called lactose, which increases calcium uptake.

Other dairy products that contain large amounts of calcium include cottage cheese and yogurt. Many people can't break down lactose, however, and this causes intestinal discomfort. One solution is to use lactase supplements, made of an enzyme that breaks down Lactose. Tofu, a soybean product also contains fair amounts of calcium. Various forms of supplemental calcium exist for those who just won't eat calcium-rich dairy products, including calcium lactate gluconate and calcium carbonate.

Calcium carbonate is found in Turns, an over-the-counter antiacid now touted as an ideal calcium supplement. It's true that calcium carbonate contains more elemental, or actual amounts of, calcium than other sources, but it's best absorbed when taken with meals. And a recent study showed that large amounts of calcium carbonate may interfere with protein absorption by preventing the conversion of pepsin (a protein-digesting enzyme in the stomach) into its active form. A 1987 Baylor University study compared absorption rates of various calcium supplements and found them all to be about the same. All of them showed absorption rates similar to the calcium in milk. This study, however, involved younger subjects. Some older people lack sufficient amounts of hydrochloric acid in their stomachs, which is needed for calcium absorption.

In that case, the best supplement is calcium citrate, which is more expensive but doesn't require acid for absorption. Other studies show that calcium may interfere with iron absorption if the two are taken concurrently. This could pose a problem for women who consume low-iron diets. A simple solution is to separate your iron from your calcium supplements. Taking calcium before bed offers the double advantage of having a relaxing effect and promoting calcium uptake into bone.

Avoid supplements such as bone meal and dolomite that contain sufficient amounts of calcium but may be contaminated with lead- which is bad for your brain. If you want to take Turns (calcium carbonate) as a supplement, be aware that Turns lacks the cofactors mentioned earlier that maximize calcium absorption. Other antacids, such as Rolaids, contain aluminum, which promotes calcium excretion. You can test the absorbability of a calcium pill by letting it dissolve in a small glass of plain vinegar. If it's still intact after 30 minutes-forget it, use a different brand.





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