Pamela A. Popper, Ph.D., N.D.
Wellness Forum Health
A common misperception regarding nutrition is that more is always better. For example, if a small amount of a nutrient in food is good for the body, large amounts of that same nutrient in supplement form must have an even more profound effect on health. It sounds right, but it isn’t. Higher intake of isolated nutrients is sometimes is not only not better, it can make things worse.
Take calcium for example. According to many experts and government agencies, women age 50 and younger need to consume 1000 mg of calcium daily, and if they are over age 50, 1200 mg per day in order to maintain healthy bones. Supplement sellers and promoters of fortified foods tell the public daily that calcium builds strong bones, and that supplements and fortified foods are needed in order to get “enough.” But a growing body of evidence shows that this is not the case. In fact, according to a new study, higher calcium intake is associated with an increased risk of fracture risk.
Chinese researchers looked at calcium intake and fracture risk in older men and women who were eating a mostly plant-based diet. The researchers reported that calcium intake higher than 778 mg per day or lower than 275 mg per day increased the fracture risk for men. For women, calcium intake higher than 651 mg or lower than 248 mg increased the fracture risk. In other words, very low and very high calcium intake is associated with increased fracture risk.[i]
The World Health Organization recommends 400-500 mg per day of calcium and states that there is no evidence of benefit at higher intake.[ii] The National Health Service in the United Kingdom recommends 700 mg per day.[iii] UK guidelines also include many non-dairy sources of calcium such as green leafy vegetables, soybeans, tofu, and nuts.
U.S. researchers are starting to change their minds about calcium needs too. Dr. Walter Willett, chair of the Department of Nutrition at Harvard T.H. Chan School of Public Health, says that women would be better off if they consumed less calcium.[iv]
The recommendation to consume 1200 mg of calcium per day was not supported by evidence at the time it was originally established. Instead, researchers hypothesized that taking in more calcium would result in higher blood levels of calcium, which would in turn keep the body from releasing calcium from the bones to buffer acidity. The researchers neglected to take into consideration several things, including that nutrient absorption relies on several factors, which include the combination of foods consumed, the health of the gut microbiota, and the overall dietary pattern. They also failed to consider that when calcium intake is too high, the body restricts calcium absorption in order to prevent the deposition of excess calcium in the arteries and soft tissues of the body.[v] The amount of calcium or any other nutrient consumed is not necessarily an indication of how much is absorbed.
People who eat a well-structured plant-based diet can easily consume enough calcium daily based on actual daily needs, which are 400-500 mg per day. For example, a medium-sized orange contains 100 mg of calcium and 4 ounces of broccoli contains 112 mg. And well-structured plant-based diets are low in protein, which reduces the release of calcium from the bones.[vi] And smaller amounts of calcium from food result in stronger bones than larger amounts from supplements.[vii]
More is not better.
- Fang A, Li K, Guo M et al. “Long-term Low Intake of Dietary Calcium and Fracture Risk in Older Adults with Plant-Based Diet: A Longitudinal Study from the China Health and Nutrition Survey.” J Bone Min Res published online ahead of print DOI: 10.1002/jbmr.2874
- Prentice A. “Diet, Nutrition and the Prevention of Osteoporosis.” Public Health Nutrition 7(1A):227-243 DOI: 10.1079/PHN2003590
- How much calcium do you really need? Harvard Women’s Health Watch August 1, 2015 http://www.health.harvard.edu/staying-healthy/how-much-calcium-do-you-really-need
- Heaney RP, Saville PD & Recker RR “Calcium absorption as a function of calcium intake” J Lab Clin Med 1975; 85:881-887.
- Margen S, Chu J-Y, Kaufman NA, et al. “Studies in calcium metabolism. I. The calciuretic effect of dietary protein. “ Am J Clin Nutr 27 (1974)L584-589
- N Napoli et al, “Effects of dietary calcium compared with calcium supplementation on estrogen metabolism and bone mineral density,” Am J Clin Nutr vol 85:1428-1433