Plates Not Pills: Calcium
This essential micronutrient contributes to your performanceAugust 17, 2011
Don’t miss our unassumingly healthy, calcium-rich recipe for chocolate mousse
Although macronutrients supply a bulk of your energy needs, calcium is one of the many micronutrients that play a significant role in how your body performs during exercise. It’s one of the most abundant essential minerals in the human body, with roughly 99 percent found in the teeth and bones. The National Dairy Council, the notable “Got Milk?” campaign, and the National Osteoporosis Foundation have all encouraged Americans to consume dietary calcium for bone health as well as for blood clotting and transmission of nerve cell signals. Although calcium is most often associated with preventing osteoporosis, athletes should be delighted to hear that calcium aids in muscle contractions and may prevent muscle cramps and weakness during activity. When there is adequate calcium flow into the muscle cells during exercise, the magnesium helps muscles properly contract and relax.
As an active person, you are constantly placing stress on your body. Consuming foods such as dark leafy greens, milk, and yogurt are essential in ensuring that you have enough calcium to support the bone rebuilding process. Strong bones not only allow for strong and powerful muscles, but your risk for stress fractures and other debilitating injuries may also be reduced. By meeting your daily recommended calcium needs through naturally-occurring or calcium-fortified foods, you can greatly reduce your chance of nutritional deficiencies. When a calcium deficiency exists (either through inadequate intake or improper absorption), the bloodstream will have no choice but to steal calcium from bones in order to help keep the body balanced. When there’s too much of this borrowing going on, along with increased stress on the skeletal system, the result may be significant bone loss. This can lead to increasingly weak bones that under certain circumstances may eventually break.
The Food and Nutrition Board’s recommends a daily intake of 1,000 mg for all individuals between 19 and 50 years. For those between the ages of 51 and 70, they advise 1,200mg for females and 1,000 mg for males.¹ For optimal bone density, however, absorption of plant and animal-based calcium is especially important. Depending on the food sources at your meal, around 30 percent of dietary calcium may be properly absorbed¹. While vitamin D improves calcium absorption, phytic acid and oxalic acid (found naturally in some plants) may actually inhibit absorption. As for beverages, alcohol may reduce absorption of calcium, whereas moderate caffeine consumption may have no effect on bone density (if calcium and vitamin D intake is optimal).² However, the research regarding caffeine in relation to bone density is ongoing. Lastly, because calcium is eliminated from the body through sweat, be mindful of your electrolytes (sodium, potassium, chloride, magnesium and calcium), during and after workouts. Also, for athletes who routinely take glucocorticoids (ex. Prednisone), be sure to carefully monitor calcium intake as long-term steroid use may inhibit osteoblast production, increasing the risk for osteoporosis.³
Get it: Milk, Dairy, and Dairy Alternatives
Although you can meet recommended intakes of calcium from plant-based foods, it is advised to consume a variety of calcium-rich foods, such as low-fat dairy. Cow’s milk is the most affordable and practical method of getting good-quality calcium and protein in your diet, and is an ideal post-workout recovery drink. For individuals concerned about rBST (recombinant bovine somatotropin), an artificial growth hormone used to boost milk production, the Food and Drug Administration has determined it safe for consumption. Nonetheless, further research on the hormone is needed, and a good selection of “rBST-free” brands are available.4
As an alternative, almond milk meets around 30 percent of the calcium content needed for a 2,000 kcal/day diet—making it similar to cow’s milk. However, to help meet your protein needs, you’d need to consume around 64 ounces of almond milk to receive the same amount of protein in 8 ounces of cow’s milk. For vegans, vegetarians, and those who are lactose intolerant, soy milk is a healthy alternative to cow’s milk as it contains comparable protein and calcium. Additionally, soy milk is often fortified with vitamins which help prevent deficiencies such as vitamin B12.
As for yogurts, reach for nonfat, plain Greek yogurt which will meet around 20 percent of your daily calcium needs (per 6-ounce container), as well as providing your body with good bacteria (probiotics). Because Greek yogurt is strained, it contains almost double the protein content compared to the typical yogurts. The bottom line is, when choosing the best sources of calcium for your diet, don’t forget to read labels to ensure that you’re consuming quality nutrients with little to no added ingredients. Here’s a list of common dairy products and the amount of calcium per serving they contain:
-Nonfat yogurt (8 ounces) – 490 mg
-Skim milk (8 ounces) – 300 mg
-Mozzarella cheese (1 ounces) – 210 mg
-Parmesan cheese (2 tbsp grated) – 140 mg
Other calcium-rich foods:
Your daily dose of calcium need not come from dairy. Vegans and those who follow lactose- or dairy-free diet can turn to the following calcium-rich foods to ensure they’re getting enough.
-Blackstrap molasses (2 tbsp) – 400 mg
-Fortified juice (8 ounces) – 300 mg
-Fortified cereal (1 cup) – 300 mg
-Swiss cheese (1 ounce) – 270 mg
-Tofu (4 ounces) – 200-300 mg (check out our recipe for chocolate mousse)
-Tempeh (1 cup) – 215 mg
-Soybeans, cooked (1 cup) - 180 mg
-Navy beans (1 cup) – 130 mg
-Spinach, cooked (1/2 cup) – 130 mg
-Arugula (1 cup) – 125 mg
-Black beans (1 cup) – 120 mg
-Broccoli, cooked (1 cup) – 94 mg
-Kale, cooked (1/2 cup) – 90 mg
-Almonds (1/4 cup) – 90 mg
-Acorn squash, cooked (1 cup) – 90 mg
-Oysters (3 ounces) – 80 mg
-Kiwi (1 cup) – 50 mg
Source: Composition of Foods. USDA Nutrient Data Base for Standard Reference, Release 18, 2005.
1. Committee to Review Dietary Reference Intakes for Vitamin D and Calcium (2010). Dietary Reference Intakes for Calcium and Vitamin D. Food and Nutrition Board, Institute of Medicine. Washington, DC: National Academy Press. 2. Heaney, RP. (2002). Effects of caffeine on bone and the calicum economy. Food Cehm Toxicol. 40(9): 1263-70. 3. De Nijs, RN. (2008). Glucocorticoid-induced osteoporosis: a review on pathophysiology and treatment options. Minerva Med. 99(1): 23-43. 4. Department of Health and Human Services (1994). Voluntary labeling of milk and milk products from cows that have not been treated with recombinant bovine somatotropin. Federal Registrar. Retrieved August 13, 2011 from http://www.fda.gov/Food/GuidanceComplianceRegulatoryInformation/GuidanceDocuments/FoodLabelingNutrition/ucm059036.htm.
Marni Sumbal, MS, RD, CISSN is a Registered Dietitian with a Master of Science degree in Exercise Physiology. Marni is certified in sports nutrition and is a USAT Level-1 coach. Marni is currently training for her 2nd Ironman World Championship and enjoys spending time in her kitchen, coming up with vegetarian creations. If you can’t find her writing this monthly column, cooking or training, she is likely outside running with her furry best friend, Campy.