Like magnesium (which I discussed last week here), calcium is a complex topic and plays a much bigger role than just its affect on bone health. It’s now being called into question due to certain health risks it poses. Let’s take a closer look at what calcium really does for you, how it relates to vitamin D, and whether supplementation makes sense or not.
What calcium does in your body
You have learned through the years about the need for calcium for strong bones, correct? Indeed, more than 99 percent of your calcium is stored in bones and teeth for a solid structure. It also is critical for the skeletal system and to facilitate smooth muscle movement. It also allows nerve to give their impulses. But there’s more. Calcium helps release hormones and enzymes which affect nearly every function of your body.
Yet if you have so much calcium stored in your bones, why would you need to worry about getting enough? The answer is that you shouldn’t, unless your body is losing it too fast or not able to absorb enough over time. There are a few reasons for this to consider.
Why you may not be getting enough calcium
If you are a woman near or in menopause then you need to keep reading. With menopause comes a greater calcium bone loss through the kidneys and out the urine due to lack of estrogen. [1] In case you did not already know, real estrogen (from a compounding pharmacy that provides bioidentical sources, not synthetic pills from a pharmaceutical company) contains two estrogens called estradiol (E2) and estriol (E3) in a one-to-one ratio and as much as a one-to-four ratio. They include estriol (E3) because it has a far lower risk of cancer than synthetic estrogen, plus it is known to increase bone density [2] [3] and improve heart health. [4] Plus, in advancing age you are expected to lose increasing amounts of calcium through urinary excretion.
Here are more reasons why calcium can be reduced. Before menopause a woman who does not have menstrual periods (amenorrhea) has decreased calcium absorption and increased urinary loss. If you have lactose intolerance or just avoid dairy altogether, you will need to eat other calcium-rich foods (discussed below). Low vitamin D or lack of sunlight to convert it to its active form reduces calcium absorption, too.
Medicines are also known to affect your calcium. Thiazide diuretics (hydrochlorothiazide) cause urinary retention, while loop diuretics (furosemide) cause urinary calcium losses. Antacids containing aluminum or magnesium increase urinary losses as well. Stimulant laxatives reduce calcium absorption, while glucocorticoids (prednisone) deplete calcium from bones to promote osteoporosis when used consistently longer than two months.
What happens if you have too much calcium?
Let’s look at how your body controls the amount of calcium circulating in your blood. It uses specific hormones (parathyroid hormone, vitamin D, and calcitonin) to do it. Of these three, only vitamin D level can be controlled by you—through supplementation or sun exposure. These hormones control your calcium levels through intestinal absorption, kidney excretion, and bone resorption. When your blood calcium levels fall too low, your intestines absorb more calcium, your kidneys retain more calcium, and your bones release more calcium. When it is too high, the opposite effects should occur.
Without a blood measurement of 25-hydroxy vitamin D it can be confusing to know how much vitamin D3 to take as a supplement. This is what happened to my sweet aging mother recently. Her blood tests reported high serum calcium, but her doctor had her taking 5,000 IU of vitamin D3 daily (I asked her to change this to twice weekly).
Not enough calcium linked to osteoporosis
There is no doubt that low calcium (along with low vitamin D) leads to thinner bones, called osteoporosis. This condition has been well-studied and there are several medications to treat it. Yet from a natural health standpoint, it makes more sense to first address the underlying causes as best you can: do you have excellent dietary calcium intake? Do you have low vitamin D levels? Do you have normal kidney function? Do you regularly perform weight-bearing exercise? Do you have optimal hormone function—including estrogen and progesterone? After this maybe consider a prescription drug such as Fosomax® or Actonel®.
Too much calcium (from supplements) is linked to many diseases
I don’t find any correlation in the scientific literature between high amounts of dietary calcium and disease—because your body is smart—but calcium from supplementation is a completely different story.
Did you know that calcium is the chief component of more than 80 percent of kidney stones, and that kidney stones are linked to calcium supplementation (plus mild dehydration)? Calcium supplements can also cause constipation. Worse, some studies show calcium supplementation may increase prostate cancer risk. But the literature is becoming clearer that calcium supplementation increases heart disease risk. Let’s look at a few studies to understand this more.
In a randomized placebo-controlled clinical trial in New Zealand involving 1,471 healthy post-menopausal women, researchers reported that calcium supplementation was clearly associated with “upward trends in cardiovascular event rates.” The 2008 report [5] was published in the British Medical Journal.
A subsequent report in 2013 [6] of retrospective data among 36,282 postmenopausal women participating in the Women’s Health Initiative who took a daily 1,000 milligram (mg) supplement of calcium with 400 international units (IU) of vitamin D found a 35 percent reduction in hip fracture with no appreciable increased in heart attacks over seven years. These finding support the safety and efficacy of calcium supplementation indeed. Maybe it was the type of calcium used, which I’ll address later in this article.
A more recent meta-analysis [7] of the peer-reviewed medical literature reported in 2013 indicates further that while calcium supplementation showed overall only a 10 percent decrease in fracture rates (considered borderline statistical significance), it increases the risk of heart disease in older women and also in patients with kidney impairment. In fact, they found overall a 27 percent to 31 percent increase in the risk for heart attack and a 12 percent to 20 percent increase in the risk for stroke. Not good for older women for sure. Worse still, when they looked at those who also took vitamin D with calcium, it did not lessen these adverse effects. They concluded that the risk of heart disease outweighs the expected value for bone strengthening for older women and those with weak kidneys.
Subsequently, U.S. Preventative Services Task Force has reviewed more than 135 studies and now recommends that in older men and women there is not enough evidence to determine whether vitamin D and calcium supplements at larger doses can prevent fractures and that lower doses of vitamin D and calcium supplements do not prevent fractures in older women and may increase the risk of kidney stones. [8]
How best to get enough calcium from your diet
You should expect to get enough calcium (1,200 mg daily) from eating the following kinds of food:
- Milk, yogurt and cheese, which are the main food source for most Americans.
- Kale, broccoli, cabbage and almonds.
- Fish with soft bones (that you eat) such as canned sardines and salmon.
- Most grains, but best is sprouted or boiled as cereal, not breads or pastas.
- While many foods have calcium added, this source is often calcium carbonate which is not recommended (see below) and therefore has less benefit than expected.
What kinds of calcium supplements?
As mentioned, calcium carbonate is the chalk you’ll find in the industrial world. Better forms of calcium for supplementation is calcium citrate, which is more expensive but is better absorbed independent of stomach acid or if you are on a full or empty stomach. Calcium gluconate, lactate and phosphate are alternatives. Be aware that calcium supplements can reduce the absorption of certain medications if taken at the same time: bisphosphonates (Fosamax®), certain antibiotics (Cipro®), levothyroxine (Synthroid®), and phenytoin (Dilantin®).
I invite you to read my next article on Monday about the important hormone-vitamin D3.
To feeling good for health,
Michael Cutler, M.D.
Easy Health Options
[1] http://www.fao.org/docrep/004/y2809e/y2809e0h.htm#bm17.6
[2] Minaguchi H, Uemura T, Shirasu K, et al. Effect of estriol on bone loss in postmenopausal Japanese women: a multicenter prospective open study. J Obstet Gynaecol Res. 1996 Jun;22(3):259-65.
[3] Nishibe A, Morimoto S, Hirota K, et al. Effect of estriol and bone mineral density of lumbar vertebrae in elderly and postmenopausal women. Nippon Ronen Igakkai Zasshi. 1996 May;33(5):353-9.
[4] Kano H, Hayashi T, Sumi D, et al. Estriol retards and stabilizes atherosclerosis through an NO-mediated system. Life Sci. 2002 May 24;71(1):31-42.
[5] Bolland MJ, Barber PA, et al. Vascular events in healthy older women receiving calcium supplementation: randomised controlled trial. BMJ 2008 Feb 2;336(7638):262-6.
[6] Prentice RL, Pettinger MB, et al. Health risks and benefits from calcium and vitamin D supplementation: Women’s Health Initiative clinical trial and cohort study. Osteoporos Int. 2013 Feb;24(2):567-80.
[7] Reid IR. Cardiovascular effects of calcium supplements. Nutrients. 2013 Jul 5;5(7):2522-9.
[8] file:///C:/Users/Owner/Downloads/vitdfact.pdf
