Additionally, some supplements may contain ingredients that can interact with medications, so speak with your healthcare provider before starting a new supplement 5 , 6. Furthermore, the nutrients in multivitamins may be derived from real foods or made synthetically, making it essential to purchase your vitamins from a reputable manufacturer.
In addition to vitamins and minerals, multivitamins may contain herbs, amino acids, and fatty acids — though the amount and number of nutrients can vary. Heart disease is one of the leading causes of death worldwide 7. Some studies suggest that multivitamins are correlated to a reduced risk of heart attacks and death, while others show no effects 8 , 9 , 10 , However, a more recent study revealed that among women — but not men — taking a multivitamin for more than 3 years was linked to a lower risk of dying from heart disease While some studies indicate that people who take multivitamins have a lower risk of heart disease, others have found no connection.
Overall, the evidence is mixed. Some studies suggest no effect on cancer risk, while others link multivitamin use to increased cancer risk 9 , 11 , 14 , One review examined five randomized controlled trials including 47, people.
Two observational studies, one including only women and the other including both men and women, tied long-term multivitamin use to a reduced risk of colon cancer 17 , Multivitamins have been studied for several other purposes, including promoting brain function and eye health.
Several small studies examining specific populations have found that multivitamins can improve memory in older adults 20 , 21 , Multivitamins may also affect your mood.
Research has not only revealed links between poor mood and nutrient deficiencies but also between nutritional supplements and reduced symptoms of anxiety and depression 23 , 24 , 25 , 26 , 27 , However, other studies reveal little to no changes in mood 29, Age-related macular degeneration is one of the leading causes of blindness worldwide One study found that taking antioxidant vitamins and minerals may slow its progression and help prevent it 32 , 33 , Furthermore, some evidence indicates that multivitamins may reduce your risk of developing cataracts, another widespread eye disease 35 , 36 , Multivitamins may help improve your memory and mood.
Although high doses of some vitamins and minerals are acceptable for some people, high amounts can be harmful. A large, long-term study of male smokers found that those who regularly took Vitamin A were more likely to get lung cancer than those who didn't. And a review of trials of several different types of antioxidant supplements put it this way: "Treatment with beta carotene, vitamin A, and vitamin E may increase mortality.
Vitamin C: Skip it - it probably won't help you get over your cold, and you can eat citrus fruits instead. The Vitamin C hype - which started with a suggestion from chemist Linus Pauling made in the s and has peaked with Airborne and Emergen-C - is just that: hype.
Study after study has shown that Vitamin C does little to nothing to prevent the common cold. Plus, megadoses of 2, milligrams or more can raise your risk of painful kidney stones. For years, Vitamin B3 was promoted to treat everything from Alzheimer's to heart disease.
But recent studies have called for an end to the over-prescription of the nutrient. A large study of more than 25, people with heart disease found that putting people on long-acting doses of Vitamin B3 to raise their levels of 'good', or HDL, cholesterol didn't reduce the incidence of heart attacks, strokes, or deaths.
Plus, people in the study who took the B3 supplements were more likely than those taking a placebo to develop infections, liver problems, and internal bleeding. Probiotics: Skip them - the science isn't advanced enough yet for them to have a significant benefit, and you can eat yogurt instead. Cleveland Clinic is a non-profit academic medical center.
Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Experts are at odds over the effectiveness of multivitamins.
Internist Raul Seballos, MD , notes that two large studies have finally shed some light on the subject:. But not all vitamins come with health risks — especially if you use them after consulting your doctor first. All smoked, but only some were given beta-carotene supplements. A similar result was found in postmenopausal women in the U. It gets worse.
One study of more than 1, heavy smokers published in had to be terminated nearly two years early. Compared to placebo, 20 more people were dying every year when taking these two supplements.
Over the four years of the trial, that equates to 80 more deaths. But, according a review from that noted the conclusions of 27 clinical trials assessing the efficacy of a variety of antioxidants, the weight of evidence does not fall in its favour.
Just seven studies reported that supplementation led to some sort of health benefit from antioxidant supplements, including reduced risk of coronary heart disease and pancreatic cancer. That left another 10 studies that found many patients to be in a measurably worse state after being administered antioxidants than before, including an increased incidence of diseases such as lung and breast cancer.
Linus Pauling was largely unaware of the fact that his own ideas could be fatal. In , before the publication of many of the large-scale clinical trials, he died of prostate cancer.
But did it contribute to a heightened risk? Dosing up on vitamin C does not even help us fight the common cold Credit: Alamy. Ever since Harman proposed his great theory of free radicals and ageing, the neat separation of antioxidants and free radicals oxidants has been deteriorating. It has aged. Antioxidant is only a name, not a fixed definition of nature.
At the correct dose, vitamin C neutralises highly charged free radicals by accepting their free electron. But by accepting an electron, the vitamin C becomes a free radical itself, able to damage cell membranes, proteins and DNA.
Although such simplifying of complex biochemistry is in itself problematic, the clinical trials above provide some possible outcomes.
Antioxidants have a dark side. We now know that free radicals are often used as molecular messengers that send signals from one region of the cell to another. In this role, they have been shown to modulate when a cell grows, when it divides in two, and when it dies.
Without them, cells would continue to grow and divide uncontrollably. We would also be more prone to infections from outside. When under stress from an unwanted bacterium or virus, free radicals are naturally produced in higher numbers, acting as silent klaxons to our immune system.
0コメント