Calcium supplementation again questioned, this time in Harvard newsletter

By Hank Schultz

- Last updated on GMT

Image © iStockPhoto / Zerbor
Image © iStockPhoto / Zerbor

Related tags Calcium Osteoporosis

How much calcium is too much?  Despite recent determinations by health authorities, it’s a question that won’t be put to rest.  The most recent stirring of the pot came in an interview published by the Harvard Women’s Health Watch that said recommended intake levels for women are unnecessarily high and might even be dangerous.

The opinions in the piece were attributed to Dr Walter Willett, chair of the Department of Nutrition at the Harvard T.H. Chan School of Public Health. Although national guidelines recommend that adult women get 1,000 to 1,200 milligrams of calcium a day, Willett says that’s too much.

Call for calcium recommendation to be halved

"Essentially, I think that adults do not need 1,200 milligrams of calcium a day. The World Health Organization's recommendation of 500 milligrams is probably about right. The United Kingdom sets the goal at 700 milligrams, which is fine, too. It allows for a little leeway,”​ Willett said.

“We think that the current recommendations for calcium are appropriate,”​ Andrea Wong, PhD, told NutraIngredients-USA. Wong is vice president of scientific and regulatory affairs for the Council for Responsible Nutrition (CRN).  “The totality of evidence shows the need for calcium at the levels recommended by the NIH."

Calcium intake for women, especially as they approach and undergo menopause, is of special concern because of their greater risk for developing osteoporosis, one of the conditions that can have a huge impact on quality of life for older women. The bones act as a calcium bank, so to speak, with calcium being released into the bloodstream from the bones as needed for basic functions. Bone density can drop when the pace of calcium outflow exceeds the amount of calcium needed to keep up with ongoing process of bone formation known as bone remodeling.  Vitamin D plays an important role in this process, and there is some evidence to indicate that an adequate level of vitamin K2 is also important in modulating calcium mobility.

The issue in recent years has been the question of calcium’s role in the formation of arterial plaques. Whether these plaques are a response to too much calcium circulating in the blood or are a way for the body to repair damaged portions of the endothelial layer lining the blood vessels is a matter of some debate. But there is no questions that calcified and therefore inelastic blood vessels are not a good thing leading to elevated blood pressure and higher heart attack risk. 

"The recommendation was based on calcium balance studies that lasted just a few weeks. In fact, calcium balance is determined over the course of years,"​ Willett said. Among the arguments against high levels of calcium supplementation put forth in the article were these: 

  •      Calcium and vitamin D supplements don't prevent fractures.
  •      High calcium intake alone—either from food or supplements—doesn't prevent hip fracture.
  •      High doses of calcium from pills increases the risk of kidney stones.
  •      Calcium supplements may increase the risk of heart attack.
  •      Higher levels of dietary vitamin D may be necessary to prevent bone loss.
Hips © stockdevil
High calcium intake alone - either from food or supplements - doesn't prevent hip fracture, says Dr Willett. Image © iStockPhoto / stockdevil

Bias against supplementation

The article seems to share the underlying bias that a number of physicians have against the whole idea of supplementation for calcium and other nutrients. The article includes a chart of calcium-rich foods that can be consumed to reach adequate intake levels including collard greens, kale, sardines and many dairy foods.

But Wong said that the old saw that it’s best to get your nutrients from the diet, while fine in theory, doesn’t match modern reality. Even with access to a rich array of food choices, Americans consistently fall short in key nutrients, calcium among them.

“Research shows that calcium continues to be a shortfall nutrient,”​ Wong said. “We have to remember that this is one person’s opinion. While we have great respect for Dr Willett, this does not appear to be based on current science. In the past couple of years there have been at least five studies that have not shown any increased risk associated with calcium supplementation.”

To read the Harvard Women's Health Watch article, please click HERE​. 

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So how does a layperson know what recommendation to follow?

Posted by Sue,

Ok, so like the diet debates, what recommendation should we follow? I am not a medical person, I only read a lot of medical advice articles. I listen to my doctors. They say 1000-1200 MG of Calcium, my blood calcium levels are little lower than the good range, so I think they are right. But how can I be sure I am not taking too much????

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Calcium from diet, not supplements

Posted by Bill Sardi,

CRN has no choice but to protect the interests of its manufacturer members. Calcium supplements represent hundreds of millions of dollars in sales. Menopause is not defined as a shortage of calcium but a loss of calcium from bones due to a hormone shortage, not a mineral shortage. Pour more calcium in and more will be lost from bone and deposited in arteries. That is what current studies show. Calcium from the diet is sufficient. Current dietary intake for dairy-consumption is 800-1200 mg so supplements are not needed. The oft quoted 1200 mg/day requirement is comprised from diet + supplements.

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