One of the questions I ask each patient when she comes in for her check-up is whether she tales calcium and vitamin D. I know a lot of you have read media reports voicing concern about excess calcium intake. And indeed, many of my patients have simply stopped taking calcium supplements as a result of these reports, despite the fact that may not get adequate calcium in their diets. Unfortunately, the current typical answer that I seem to get regarding milk product consumption is “yes, I add milk to my coffee”…
I thought, therefore, it would be a good idea to summarize the recent article that appeared under the medical news and perspectives portion of JAMA. It reported on the latest data that has caused concern about excess calcium consumption. The authors noted that more than half of US women who are middle age or older take calcium supplements and that there are now concerns about potential cardiovascular disease risk with the supplements. A new study published in the British Medical Journal in 2013 may have added to this concern, but it came with some caveats. (As do all studies!)
The study comprised 61,433 women who were followed up for up to 19 years. The researchers used questionnaires to get information about the women’s diet and supplement use and followed their subsequent health. They found that women who consumed more than 1400 mg of calcium daily had a higher rate of death from all causes (about 40%) then women who consume between 600 mg and 1,000 mg daily. Women who consumed more than 1400 mg of calcium daily also had a higher risk of death from cardiovascular disease (49%) and ischemic heart disease (14%), but not stroke. The women who were at highest risk were those who had both a high dietary intake of calcium (more than 1400 mg) and additionally took calcium supplements. They had an all cause- risk mortality increase of 2.57 ( two and a half times more) or, if want you want to use percentages, an increase of 257 %.
The authors tried to explain these findings by stating that excess intakes of calcium may impact physiologic control of calcium levels in the body and higher levels may increase the growth of fibroblast factors. Excess fibroblast activity can stimulate the thickening of the lining of blood vessels causing subsequent lack of pliability and an inability to dilate. This can then decrease the flow of blood to the heart and other vital organs hence, contributing to higher rates of cardiovascular and all cause mortality.
Remember you get calcium in many forms of food, both dairy and non-dairy. A cup of low-fat or nonfat yogurt has as much as 400 mg of calcium (once fruit is added however, you lose about 100 mg) and a glass of nonfat milk has 300 mg. An ounce of sliced cheese averages 200 mg but surprisingly 1/2 cup of nonfat cottage cheese only has 80 mg. A cup of broccoli gives you 170 mg of calcium. Collards and dried beans do better at 270 mg per cup. Three ounces of canned sardines with bones (it’s “in dem bones”) has 370 mg and the same portion of canned salmon has 200 mg. It’s thought that the average diet without special high calcium foods or milk has about 200 to 250 mg of calcium.
We do utilize and excrete calcium on a daily basis and we need approximately 1000 mg “to keep on top of what we lose” as adults and 1200 mg in our later years. Low calcium intake has definitely been associated with low bone mass or osteopenia and then comes menopause and age which compound this loss. Women have a greater than 40 % lifetime risk of developing an osteoporotic fracture. So ultimately we have to weigh your bone health together with your heart health. The evidence so far is that we need our calcium, but ultimately it’s best to get it through diet if at all possible and supplement only what is missing.
Read the label of contents on what you eat and drink. It will state the percent of calcium in a portion of the food that has been labeled (obviously you can’t do this with fresh veggies, but you can use the above reference or consult a nutrition chart.) Remember the percent is calculated on a daily total of 1000 mg so 30% is the equivalent of 300 mg.) If you do not reach that 1000 mg goal through your food, then go ahead and supplement. The authors of the British Medical Journal article emphasize that calcium supplementation should be taken by “people with a low intake of calcium rather than increasing the intake of those already consuming satisfactory amounts.”