April 25, 2013

Verdict on the Four Most Popular Supplements: Multivitamins, Calcium, Fish Oil, Vitamin D

Above: the stash of dietary supplement pills I pitched out several months ago. They had accumulated during all the years when I thought "the more pills, the better." I'd also been in the clutches of a nutritionist who said I was deficient in all sorts of vitamins and minerals . . . and who just happened to have supplements to sell that would correct my deficiencies. 

I now realize that buying those supplements was like flushing money down the toilet. In many case, it was literally true. When the body gets more vitamins or minerals than it needs, the excess is excreted in urine.

I haven't been alone in my supplement OD habit. Americans spend about $28 billion a year on them. Mounting evidence shows we'd be better off to forget about pills and concentrate instead on a healthy diet. 

Let's take a look at the four most popular dietary supplements, all of which I've taken.

1. Multivitamins and minerals
Do you think of taking a daily multivitamin as a form of "health insurance"? If so, you're one of an estimated 75 million Americans who pop these pills every day, making multivitamins our most popular dietary supplement. 

Studies showing an association between taking multivitamins and reduced risk of cancer or heart attack do not establish a cause-effect connection. Most researchers point out that people who take multivitamins are more likely to eat heart-healthy diets, exercise, refrain from smoking, and try to keep their weight down.

The consensus recommendation is this: when possible, get your nutrients from food and not pills. While multivitamins are generally assumed to be safe, some contain excessive doses of nutrients, 19 or more times the recommended daily intakes. 

For instance, some supply high does of vitamin A, which may weaken bones. Heavy doses of copper can interfere with the absorption of zinc, and vice versa.

But some groups may not be able to obtain all the vitamins and nutrients they need from diet. For example, some of us old folks have a diminished capacity to absorb vitamin B-12 from food. Especially in cold northern winters, it can be difficult to get adequate vitamin D from sunlight and diet. Most multivitamins, however, don't supply as much vitamin D as experts recommend.

Strict vegetarians may not get enough B-12, zinc, iron, or calcium. Women of child-bearing age and pregnant women may have special needs not met through diet. 

If you have any of these concerns, it might be best to talk with your doctor about specific supplements you may need, rather than relying on all-purpose multivitamins. The blood results from my annual physical last year showed that I was low on vitamin D, so I now take a vitamin D-3 pill with breakfast every morning. 

I'd much rather go this route than try to figure out which among the staggering array of multivitamins might provide enough vitamin D without overloading my system with other vitamins or minerals. 

2. Calcium
Not long ago, calcium was the least controversial dietary supplement. Millions of people take calcium, hoping to keep their aging bones strong and prevent osteoporosis-related fractures, which half of all women eventually experience, as do many older men. There were questions. Which form of calcium was best? Did it cause kidney stones? What other nutrients -- if any -- should the supplement contain?

Recent news suggests that we should consider NOT taking the pills. Here are two recent reports:
  • Several studies and one analysis of earlier research suggest that calcium supplements modestly increase heart attack risk. The clinical trials had some serious methodological flaws. Nevertheless, the negative studies raise concerns that require further research. Some researchers suggest that it's the high doses taken in concentrated form (often on an empty stomach) that create potential problems.
  • Last June, an expert panel, part of the Preventive Services Task Force that advises the government on medical matters, concluded with "moderate certainty" that standard daily doses of calcium (1,000mg) and low doses of vitamin D (400 IU or less) do not prevent fractures in postmenopausal women without osteoporosis. Such women were advised not to take the supplements. But these are draft guidelines, and many researchers have raised objections to them.
The sage advice to get one's vitamins and minerals primarily from dietary sources and not pills is now being recommended with respect to calcium. It's important to note that the potential cardiovascular risks of calcium apply to supplements alone, not dietary calcium. In fact, several studies have linked high-calcium diets to low rates of heart disease. 

Getting sufficient calcium (1,200mg if you're over 50) without supplements is pretty easy, especially for a fish-lover like me. Good sources of calcium include canned salmon and sardines with edible bones; green vegetables such as kale, turnip and collard greens; and non-fat dairy products like milk and yogurt. Dried figs, oranges and almonds are good choices too.

just described a big part of my diet. 

3. Fish Oil
About 10 percent of Americans take fish oil (omega-3) capsules, the third most widely used dietary supplement after multivitamins and calcium. Since 2004, the FDA has allowed fish oil supplements to carry a "qualified" health claim linking them to reduced heart disease risk, but the label must state that the evidence is "not conclusive."

As it turns out, "not conclusive" is an understatement. In fact, negative findings from clinical trials and analyses  during the past two years call into question the proposed cardiovascular benefits of fish oil supplements.

Is it time to deep-six your fish oil pills? Mine are somewhere in that pictured bowl above of pills I no longer take. 

The American Heart Association still advises people with heart disease or high triglycerides to consider taking the supplements after consulting their doctors. But for the general population, a better bet is to get your fish oil from two or three servings of fatty fish a week.

Sardines are one of the richest sources of omega-3 fats, richer than many fish oil supplements. Since sardine populations are abundant in so many parts of the world, they're a good ecological choice as well. 

Fish oil capsules contain only the two main omega-3 polyunsataurated fats in fish. But eating fish provides important "extras" -- vitamins, minerals, and other fats and nutrients that may work with the omega 3's to protect the heart and promote overall health.

4. Vitamin D
Vitamin D is best known as being good for the bones. Higher vitamin D levels have been linked to reduced risk of fractures. There is encouraging evidence that supplements can increase bone mineral density and decrease fractures.  

But the evidence is very murky as to whether vitamin D supplements can prevent other chronic diseases.  Some researchers speculate that vitamin D may end up like vitamin E -- the initial promise was not corroborated by large clinical trials. Recent studies conclude there's insufficient evidence that vitamin D prevents heart disease or colds.

A research report last year from the University of Copenhagen showed a "Goldilocks effect" for vitatmin D: it lowered mortality risk generally, but it increased mortality risk when the vitamin's level in blood stream was too high. 

If you live north of Atlanta, the sun just doesn't get high enough in the sky during the winter for sun's UVB rays to penetrate the atmosphere. Those UVB rays convert into vitamin D.

As we age, vitamin D receptors in the skin decline, so it's almost impossible to get enough vitamin D from sun exposure.

Dietary sources of vitamin D include oily fish (herring, salmon, mackerel, and sardines), fortified dairy products, and some fortified cereals, juices, soy milk, and margarine. 

A blood test can detect vitamin D deficiency. My last physical exam showed that shortage, so I now take 1,000mg of vitamin D-3 with breakfast. 

In 2010, the Institute of Medicine issued vitamin D recommendations for bone health and fracture reduction.  It concluded that the evidence for all OTHER benefits from vitamin D was "inconsistent and/or inconclusive or did not demonstrate causality." It also concluded that most of us don't need the supplement.

The recommended daily intake is 600 through age 70, and 800 IU above 70. It doubled an earlier safe upper limit to 4000 IU a day. Many prominent experts criticize these limits as too low. Rigorous clinical trials are underway, but we won't have results for years. 

1 comment:

Bhawana said...

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