I recently suggested a particular calcium supplement formula to female client. Each tablet contains 500mg of calcium, so my understanding is she should take three per day for the 1500mg suggested for women. My client told me she read an article that states the body can only absorb 300mg at a time. What is the theory behind the rate that calcium can be absorbed? How much at a time, and why?
These are great questions, and there is not one definitive answer, but I can make good suggestions based on research.
Calcium is a large molecule mineral therefore it needs to have an amino acid carrier to be absorbed. For calcium to be well absorbed and taken up by the body, calcium requires a high acidic environment. So... calcium carbonate is a fine choice for calcium due to the fact that there is a lot of calcium attached to the carbonate however, it does require that someone has good digestive health due to the need for high acidity.
Calcium citrate is considered the preferred calcium for the older subset due to the fact this calcium comes attached to citric acid and provides a fair amount of acidity and this bond is a weak one and the calcium is released well. The only downside is you can't stuff as much calcium in calcium citrate so as one tries to take the RDA of 1000 mg per day...in calcium carbonate you could take that in two tablets per day whereas calcium citrate you would have to take three to four tablets per day to get the 1000mg. The best way to take calcium is with food because you want to create an acidic environment and take no more that 400 to 500 mg per day. This range has been shown to be the best absorbed. Anymore at one time, some is rendered unavailable.
Recent studies show that women who want to maximize the ability for the body to absorb calcium should take their largest dose before bed and take it with magnesium, Vitamin D and zinc. These are key cofactors for absorption, at night when the hormonal profile is heightened for calcium uptake to the bones.
Lastly, antacids are not a good choice for calcium. Because they are specifically designed for neutralizing the acidic environment, there is talk in the calcium circles whether any of the calcium is actually absorbed. Best to emphasize foods and good supplements.
Following is a list of high calcium foods:
8 oz. low fat plain yogurt
1 oz parmesan cheese
4 oz tofu
1 cup collard greens
1 cup low fat milk
1 cup fruited yogurt
1 cup soy milk
1/2 cup canned salmon
1 cup calcium fortified orange juice
1 cup black eyed peas
2tbsp sesame seeds
1 cup okra
1 cup bok choy
5 medium figs
3 1/2 oz scallops
1/4 cup almonds
1/2 cup dried apricots
250-500 mg (depending what calcium agent used)
- Herb Research Foundation information packet: 2000 www.herbs.org
- Rico, H et al. Bone Mineral 1992;16:131.
- Germano, C. Whole Foods 1998, 55.
- Welton, DC.et al. J Clin Invest 1997;99:1287.
- Nicer, MJ. Calcium Bioavailability. J of Clin Endo and Met. 1985;61:391.