By Maureen Williams, ND
Healthnotes Newswire (October 11, 2007)—People who exercise strenuously lose critical nutrients in their sweat, most notably sodium. New research shows that women might also lose enough calcium during strenuous exercise to warrant taking extra to compensate.
Exercise could be considered a fountain of youth: it helps with weight management; prevents diabetes and heart disease; relieves depression, anxiety, and symptoms of menopause; improves thyroid function; prevents age-related cognitive decline; and reduces the risk of many cancers.
However, exercise can also lead to loss of minerals through sweat. A few studies in men have reported that calcium loss is higher during vigorous physical activity. Sweat collected from male basketball players after three days of intensive practicing had calcium levels high enough to suggest that some of the lost calcium came from skeletal stores.
The new study, published in Medicine and Science in Sports and Exercise, included 26 healthy premenopausal women who were regular exercisers. The women ate a carefully prescribed diet providing 300 to 350 mg of calcium per day and took a supplement with 148 mg of calcium plus 400 IU of vitamin D once per day throughout the entire study. The study consisted of three phases: placebo and no exercise; placebo and one hour of strenuous exercise per day; and 800 mg of additional calcium and one hour of exercise per day.
The women lost more calcium than they took in during the placebo/exercise phase. Adding the extra calcium, however, led to a positive calcium balance (calcium loss was less than calcium intake).
The low-calcium diet resulted in a negative calcium balance (greater loss than intake) even without exercise. However, calcium loss was even greater when the women exercised.
Many women’s diets are similarly low in calcium—among study participants, one-fourth had daily calcium intakes below 600 mg. For these women, the small increase in calcium loss during exercise could have a detrimental effect on bone mineral status, and replacing that calcium might be especially important.
These findings suggest that regular calcium supplementation might benefit physically active premenopausal women by correcting a negative calcium balance caused by the combination of inadequate intake and losses through sweat.
“Although one hour of strenuous exercise had a modest effect on dermal [skin] calcium loss, achieving recommended dietary calcium intakes may be particularly important in physically active women,” the study’s authors stated in their conclusion. Eating dark green vegetables, soy foods, sea vegetables, and canned fish with bones such as sardines and salmon can help women reach the recommended daily allowance of 1,000 mg per day even if they don’t eat lots of dairy.
(Med Sci Sports Exerc 2007;39:1481–6)
Maureen Williams, ND, received her bachelor’s degree from the University of Pennsylvania and her Doctorate of Naturopathic Medicine from Bastyr University in Seattle, WA. She has a private practice in Quechee, VT, and does extensive work with traditional herbal medicine in Guatemala and Honduras. Dr. Williams is a regular contributor to Healthnotes Newswire.
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