November 8, 2012

Supplements Update, #2: Antioxidants and Calcium -- Get Them from Food, Not Pills

Before the welcome (as it turned out) interruption of Election Day, I started a series of posts on the latest findings about dietary supplements, which we buy each year to the tune of $30 billion. The first report involved the lack of evidence for claims that supplements treat cancer, and claims for omega-3 fatty acids and antioxidants in general.

More on Antioxidants
According to current thinking, oxidative stress may play a role in aging and chronic illnesses, like heart disease, cancer, Alzheimer's, Parkinson's, even cataracts. There are thousands of antioxidants in fruits, vegetables, whole grains, coffee, tea, chocolate, and wine. As a first line of defense, some antioxidants suppress formation of free radicals, while others "scavenge" to remove them before they do damage, or repair damage when it occurs.

Some familiar nutrients that act as antioxidants are vitamins C and E, beta carotene, and selenium. Many others are phytochemicals, such as quercetin and other flavonoids. Still others are enzymes, like glutathione peroxidase and superoxide dismutase.

So, shouldn't it pay off to get more of these antioxidants from supplements, just in case we aren't getting enough in our diets? Unfortunately, no one really knows if they combat chronic conditions, or even whether oxidative stress is a primary factor in the development of these diseases. Moreover, research has shown that high levels of some antioxidants can have adverse effects. High-dose beta carotene supplements, for example, increase the risk of lung cancer for smokers. Under certain circumstances, antioxidants can turn into pro-oxidants and promote free radical formation.

It's a delicate balance, and that's why medical authorities recommend we steer clear of supplements and get our antioxidants from whole foods, which have combinations of antioxidants that work together to combat oxidation reactions.

This discussion -- with the recommendation against taking supplements -- comes from the October, 2012 issue of the University of California, Berkeley's Wellness Letter. It also reports on recent research that shoots down claims for fish oil supplements, which I covered in this series' first report.

Then yesterday, I received in the mail the Healthy Years newsletter published by UCLA. It cites flaws in this study and suggests that omega-3 fatty acid supplements might be advisable for those whose diets are low in fat and don't include fish several times a week.

The newsletter suggests:
  • fish oil supplements should contain at least 30 percent EPA/DHA, the active ingredient, 
  • you should use a complex formula to make sure your brand contains less that 50 percent filler oils, 
  • you should check to see where the fish came from (Norwegian waters are best).
Jeez! It's simpler, tastier, and cheaper to have a couple servings of fatty fish each week. I always have small tins of sardines, herring, or other fatty fish in the house, and I enjoy them with lunch at least once a week.

Calcium Supplements
German and Swiss researchers followed 24,000 adults for an average of 11 years and found that regular users of calcium supplements had an 80 percent increased risk of heart attack compared with those who didn't use supplements. However, past studies haven't supported this conclusion. The Iowa Women's Health Study found that the risk of premature death decreased 3.8 percent for those taking calcium.

For older adults, the recommended intake of calcium is 1,200mg daily. Mayo Clinic experts support meeting -- but not exceeding -- the daily calcium requirements.

But how do we know if we're hitting that goal exactly? Are we supposed to count up the milligrams of calcium we get from our fortified breakfast cereal and milk, then take a supplement that precisely matches any shortfall? Come on!

What should we do? The best advice I've found comes from an editorial that accompanied a report on the German/Swiss study in the journal Heart.

The safety of calcium supplements "is now coming under increasing scrutiny." Earlier studies suggesting women benefit from calcium supplements probably involved subjects who were already healthier than those who didn't take the supplements. In any event, the overall protection was modest -- about ten percent.

The evidence suggests that dietary calcium is healthy while calcium supplements are not. A likely explanation is that we take in small amounts of calcium at mealtimes through the course of the day, so that it is absorbed slowly. Supplements, on the other hand, cause calcium levels in the blood to spike. This flooding effect might ultimately be harmful.

The editorial continues:
Calcium supplements have been widely embraced by doctors and the public, on the grounds that they are a natural and therefore safe way of preventing osteoporotic fractures. It is now becoming clear that taking the micronutrient in one or two daily [doses] is not natural, in that it does not reproduce the same metabolic effects as calcium in food.
Since it is neither safe nor effective, boosting calcium intake from supplements should be discouraged, the editorial concludes.

Bottom Line: "We should return to seeing calcium as an important component of a balanced diet, and not as a low cost panacea to the  universal problem of postmenopausal bone loss."

Dietary Sources of Calcium
Here's what NIH's Fact Sheet says:
Milk, yogurt, and cheese are rich natural sources of calcium and are the major food contributors of this nutrient to people in the United States [1]. Nondairy sources include vegetables, such as Chinese cabbage, kale, and broccoli. Spinach provides calcium, but its bioavailability is poor. Most grains do not have high amounts of calcium unless they are fortified; however, they contribute calcium to the diet because they contain small amounts of calcium and people consume them frequently. Foods fortified with calcium include many fruit juices and drinks, tofu, and cereal.

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