Last month we discussed vitamins and minerals and took a long look at vitamin C and thiamin, two vitamins both very important for athletes. This month I want to talk about calcium. Calcium is essential for strong bones and teeth and also plays a central role in the activation of mus-cular contractions . Many people don’t get enough calcium, especially women.
Women are at risk for a very common dis-ease, osteoporosis: a condition in which the bones slowly lose calcium and weak-en as a result. A simple fall can result in a fractured hip and something as minor as stepping off a curb can crush vertebrae. Human bone lacking in calcium becomes brittle. Osteoporosis is most common in post-menopausal women. The problem is the reduction in estrogen production . Es-trogen helps keep bones strong. It is im-portant to have plenty of calcium in your bones when you enter menopause because if you start into menopause with low min-eral density (“thin bones”) then problems can occur quickly. To help in preventing osteoporosis, or reduce its impact, take in plenty of calcium to make sure your bones are strong. Though osteoporosis is more common in women, men can get it too. Build a strong skeleton when you’re young so you’ll have a strong skeleton when you’re old (1).Dairy products are high in calcium .
Milk, yogurt, and cheese are all rich cal-cium sources. This is a problem in that milk and cheese are forbidden for serious bodybuilders. We like the calcium and protein content of dairy products but the fat and sugar create disadvantages that far outweigh the advantages. Milk has an ample amount of protein but contains lactose, a simple sugar that promotes fat storage. These naturally rich sources of calcium are out of bounds. Still, we need calcium. Some vegetables contain a fair amount of calcium, especially the green leafy vegetables like spinach (1-5), but the intestines do not absorb the calcium from vegetable sources very efficiently. Vegetables contain oxalic acids, which bind to calcium and reduces its bio-availability. Bodybuilders generally avoid dairy products and vegetable calcium has absorption problems, so supplementation becomes very important. Calcium carbonate and calcium citrate are both good supplemental forms of calcium but avoid oyster shell calcium since it does not absorb well. Anyone with a history of kidney stones should probably choose calcium citrate since it is less prone to form kidney stones. The adult human body contains 1,000 – 1,200 grams of calcium, 99% of which is in the skeleton. If calcium intake is inadequate the skeleton serves as a pool from which calcium will be withdrawn for other pur-poses.
Bones are in a state of continual turnover and are constantly being re-placed and remodeled. Existing bone is reabsorbed and new bone built. Three hormones are directly involved in cal-cium metabolism: parathyroid hormone (PTH), calcitonin (CT), and vitamin D (vitamin D functions like a hormone) (1-3). Parathyroid hormone acts to release calcium from bone to increase the plasma calcium level. Calcitonin has the opposite effect, causing calcium uptake into bone. A daily intake of 1,200 mg per day of calcium is recommended – unless a person has a diagnosis of osteoporosis, in which case 1,500 mg per day is usually recom-mended (2). It is virtually impossible to obtain this amount of calcium without the use of dairy products or supplements. No problem, we at Parrillo Performance recognized the importance of calcium for athletes long ago and our Mineral-Electrolyte Formula™ provides 250 mg of elemental calcium per tablet. Two tablets of Mineral-Electrolyte Formula™ taken with five meals (or shakes) per day will yield 1250 mg of calcium per day. At less then a 8¢ per tablet, can you afford not to calcium supplement? Statistically, most women consume only about half the recommended daily amount of calcium, making it one of the most common nu-tritional deficiencies among the female population .
Osteoporosis is an insidious disease that presents few clinical signs or symptoms until a fracture finally oc-curs and then it is too late to do anything about it. It is very important for women to maintain a regulated, adequate calcium intake during their youth and middle age in order to avoid osteoporosis in later years .Vitamin D has several actions that in-crease plasma calcium levels. Vitamin D increases the efficiency of intestinal cal-cium absorption, acts to decrease urinary calcium excretion, and promotes the re-lease of calcium from bone. Since vitamin D increases calcium absorption, vitamin D deficiency will lead to low calcium. Vi-tamin D is an interesting compound that in some ways acts more like a hormone than a vitamin. It was originally classified as a vitamin because it is associated with specific deficiencies: rickets and osteo-malacia (3). Unlike other vitamins, your body is able to make its own vitamin D. It is a derivative of cholesterol called 7-dehydrocholesterol and is converted to pre-vitamin D3 in the skin during expo-sure to ultraviolet light.
As an interesting side note, in northern climates where it is cold in the winter and people don’t spend much time in the sun, inhabitants some-times develop low vitamin D levels which lead to low calcium levels. 25-hydroxyvi-tamin D3 is further metabolized in the liver and then the kidneys to produce its active form, 1,25-dihydroxyvitamin D3. The dietary form of vitamin D is also a pre-vitamin and must be converted into the active form by sequential reactions in the liver and kidney (1,2).The main function of vitamin D is to help regulate calcium and phosphorus me-tabolism. Both calcium and phosphorous are required for bone formation, nerve and energy function, and other cellular processes . When calcium or phosphorous levels are low it causes the kidneys to make more of the active form of vitamin D, which in turn goes to the intestines and stimulates the synthesis of binding proteins for calcium and phosphorous. These binding proteins increase the ab-sorption of the minerals by the intestine (3). Vitamin D also acts on the kidneys to reduce urinary excretion of calcium and phosphorous. It stimulates the release of calcium and phosphorous from bone (a good thing) and acts to maintain normal calcium and phosphorous concentrations . Vitamin D seems to have no direct value as an ergogenic aid.
There seems to be no performance boost from “extra” amounts of D but a vitamin D deficiency will certainly decrease performance. Actually, megadoses of D could be toxic if calcium levels exceed the normal range. Vitamin D deficiency in children causes rickets; a wasting disease in which in bones weaken and go soft, legs become bowed and growth is stunted. Vitamin D deficiency in adults is called osteomalacia and pro-duces skeletal weakness and pain (3). Your body can make enough vitamin D to meet your needs if you receive ad-equate sunlight exposure. Many people, workaholics, the aged and sick, do not get a lot of sun. Supplementation is highly recommended for these groups. In this country, milk and other dairy products are fortified with vitamin D and this represents the main dietary source (1-6) for most Americans. Serious bodybuild-ers and fitness enthusiasts usually won’t drink milk or eat dairy. In order to pre-vent calcium or vitamin D shortfall they should supplement. The RDA for vitamin D is 200 IU for adults beyond 24 years of age, and 400 IU for people between six months and 24 years of age (2). The solu-tion is an easy one: take our Essential Vi-tamin Formula™ and Mineral-Electrolyte Formula™ as proscribed and get on about the rest of your muscle building business. The calcium/vitamin D base is covered. We’ll talk again next month!
1 . Macroelements, Water, and Elec-trolytes in Sports Nutrition. Judy Driskell and Ira Wolinsky, CRC Press, 1999.
2. Recommended Dietary Allow-ances, 10th edition. National Research Council. National Academy Press, 1989.
3. Sports Nutrition: Vitamins and Trace Elements. Ira Wolinsky and Judy Driskell. CRC Press, 1997.
4. Sports Nutrition: Minerals and Electrolytes. Constance Kies and Judy Driskell. CRC Press, 1995.
5. Nutrients as Ergogenic Aids in Sports and Exercise. Luke Bucci. CRC Press, 1993.5. Nutrition in Exercise and Sport. I. Wolinsky and J.F. Hickson. CRC Press, 1994 .