Is your multivitamin dangerous?
The latest study on vitamins and health is out. It isn’t pretty. This research adds to other studies suggesting that multivitamins don’t improve health. They may, in fact, increase risk of chronic diseases, such as heart disease, cancer, and heart failure.
By the Numbers
Researchers in Sweden examined the connection between multivitamin use and breast cancer risk. They followed more than 35,000 women for an average of 10 years. The women were free of cancer and 49 to 83 years old at the beginning of the study.
The researchers collected and adjusted for other factors that can affect breast cancer risk. This includes family history of breast cancer, body weight, vegetable and fruit intake, physical activity levels, and use of tobacco and alcohol.
Not Best for Breast Health
After ten years, the study indicated that the women who had taken multivitamins were 19% more likely to be diagnosed with breast cancer compared with the women not taking multivitamins.
It is important to note that this is an observational study. Study participants were not randomly assigned to take or not take multivitamins. The study does not prove cause and effect. It shows an association between multivitamin use and higher breast cancer risk.
Nonetheless, the study authors noted that a connection between multivitamins and breast cancer risk is plausible. Also keep in mind that this is not the first study to show that multivitamins and other supplements may pose a risk to health.
The Bigger Picture
The first hint that isolated nutrient supplements may harm health came in the mid-1990s. Two large, randomized, placebo-controlled trials looked at this question. The trials included a total of more than 47,000 study subjects between them. They examined how beta-carotene and vitamins A, C, and E affected lung cancer risk in people at high risk for the disease. High-risk study subjects included current and former smokers and asbestos workers.
The researchers expected the vitamin supplements would decrease risk of lung cancer. They found the exact opposite. The men who had been randomized to take the supplements had a significantly higher risk of developing lung cancer. They also had a higher risk of other types of cancer. They had higher risk of heart disease and stroke too. Back to the drawing board!
Since that time, studies have continued to demonstrate that antioxidant supplements can increase the risk of cancer and heart disease. This is especially true for people who smoke or have smoked in the past.
Not So Fast
“Great,” you say, “I’m not a smoker anyway. I’ll keep taking my vitamins and beta-carotene pills.” Not so fast.
Don’t forget about the Swedish study. It points to the possibility that multivitamins increase breast cancer risk. And if you’re not a woman or not concerned about breast cancer, there are plenty of additional studies showing problems with multivitamin and antioxidant supplements.
A 2007 comprehensive research review concluded, "Treatment with beta carotene, vitamin A, and vitamin E may increase mortality." A similar review that same year stated that clinical trials of antioxidant supplements, “should be closely monitored for potential harmful effects.”
Other studies have shown that vitamins C and E do not decrease risk of Alzheimer’s disease and dementia. Unfortunately, vitamin E does increase the risk of heart failure in people with vascular disease or diabetes. Many US adults have, or are at high risk of, these conditions.
Are Isolated Antioxidant Nutrients Friend or Foe?
Multivitamins and other sources of isolated antioxidant nutrients may be problematic for several reasons. One of the most likely is that they can have a dual nature. To understand why this matters, it helps to understand oxidation.
Oxidation is a damaging process that can occur inside the body. A good way to think of oxidation is to think of rusting. But instead of causing damage to metal in the environment, oxidation causes damage to your cells. Excess oxidation is believed to contribute to the major diseases that plague us today.
This means that antioxidants, which prevent damaging oxidation in the body, should be a good thing. This is true only if they act like antioxidants. Unfortunately, when taken in isolation, antioxidants actually may become pro-oxidants. Under some conditions, antioxidant supplements promote oxidation, not stop it!
Singles Lack Synergy
Another potential issue multivitamins and antioxidant supplements is that these products lack synergy. Synergy refers to the idea that two or more things can work together in a way that their combined effect is greater than the sum of their individual parts.
Food is so incredibly complex. Trying to duplicate it in a vitamin pill is something of a fool’s errand. Consider the carotenes. Beta-carotene is the most well known of the carotenes. But there are several hundred carotenes found in nature and in the foods we eat.
Taking a pill that provides just one, two, or three carotenes is nothing like eating a beta-carotene-rich food. The food provides many carotenes plus dozens of other nutrients. And don’t forget about the fiber.
Polyphenols are another large group of nutrients. Research suggests polyphenols provide numerous health benefits…when they come from food. Taking one or two polyphenols really misses the “nutritional boat.” There are thousands of polyphenols in hundreds of foods. Polyphenols are found in foods as diverse as apples to tea and onions to berries.
Why Food Rules
And so we come back to food. Food is the ideal way to nourish our bodies. Make it a priority to fill two-thirds to three-quarters of your plate with nutrient-rich foods. Think of the bounty of the garden to guide your choices.
Brilliant orange carrots and ruby red tomatoes, shiny green pea pods and deep magenta beets, bright purple blueberries and deep purple blackberries…these are the very foods that will give your body what it needs. And getting what you need is the greatest nutritional gift you can give yourself.
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