Some of the water soluble vitamins can also cause side effects in high doses. For instance, vitamin B6 has been linked with nerve damage when taken in large doses. For a healthy adult, if supplements are used, they should generally be taken at levels close to the recommended dietary intake RDI. Information on how much a supplement provides can be found on the packaging. The fat-soluble vitamins A, D, E and K can be locked away in the liver and body fat, and stored for a long time.
The water-soluble vitamins, including B-complex and vitamin C, are mostly only stored for a shorter period of time. A vitamin deficiency takes weeks or months before it will affect your health.
For instance, it would take months of no vitamin C before you developed scurvy. An occasional lapse in good eating will not harm you, if your usual diet consists of a wide variety of fresh foods. Supplements do have a role to play for some groups of people. For instance, people on long-term restrictive weight loss diets or people with malabsorption problems, such as diarrhoea, coeliac disease, cystic fibrosis or pancreatitis, can benefit from supplements.
Folic acid supplements are strongly recommended for women planning a pregnancy to reduce the risk having a baby with neural tube defects, like spina bifida. Also, people who follow vegan diets, especially if pregnant, may benefit from vitamin B12 supplements. If you need to take a supplement, it is best to take multivitamins at the recommended dietary level, rather than single nutrient supplements or high-dose multivitamins. Many people think that vitamin C helps prevent the common cold. Despite exhaustive research across the world, there is still no strong evidence to prove this.
Some studies have shown that taking large doses of vitamin C more than 1, mg per day continuously or when you first develop cold symptoms, may ease some of the symptoms and the duration — on average, making it about half a day shorter. It does not prevent you catching a cold. You also need to consider the health risks associated with taking large doses of vitamin C. Large doses may cause nausea, abdominal cramps, headaches, fatigue, kidney stones and diarrhoea.
Excessive amounts of vitamin C in the body can also interfere with medical tests, such as diabetes tests, giving a false result. Some vitamin and omega-3 fatty acid deficiencies can lead to emotional disturbances. However, if you are feeling run down, it is more likely to be due to stress, depression or unhealthy lifestyle habits such as insufficient sleep or smoking , rather than a vitamin deficiency.
Vitamin E is widely promoted as a beneficial antioxidant that can help prevent heart disease. If yo u are unsure about taking a multivitamin , you may wish to consult with a registered dietitian who can evaluate your current diet to determine any missing nutrients. At that time , suggestions to improve your food intake of those nutrients will be provided, or one or more supplemental vitamin s may be prescribed if th at is not possible.
Always inform your doctor of all supplements you are taking in case of potential interactions with medications. M ega-dose s many times the Recommended Daily Allowance of vitamins are not recommended.
This can potentially interfere with the absorption of other nutrients or medications, or can even become toxic if too much is taken for a long period. Also be wary of vitamins that contain extras, like herbs and botanicals, which are typically lacking in research about long-term effects and potential adverse effects. Knowledge about the optimal intakes of vitamins and mi nerals to prevent chronic diseases is not set in stone.
More long-term studies looking at this relationship are needed. There is no arguing that multivitamins are important when nutritional requirements are not met through diet alone. For many diseases, but especially for cancer, only long-term trials are informative. The following studies looked at the effect of multivitamins on specific diseases and include d healthy people as well as those w ith chronic disease s at the start of the study :.
A randomized double-blind placebo-controlled trial provided a multivitamin or placebo to more than 14, male physicians, some with a history of cancer. The results did not differ among men who had a history of cancer at the start of the study and men who were healthy at baseline.
After 11 years, compared with the placebo, there was no significant effect of a daily MVI on cardiovascular events. Some research has suggested that the rates of death appear higher in people using multivitamins.
However, one major flaw in these studies was that many of the participants had already developed some type of serious illness. They may have started using vitamins after their health deteriorated, hoping for a benefit. But in those cases, taking a multivitamin might have been too late. It is important to remember that a multivitamin cannot in any way replace a healthful well-balanced diet.
The main purpose of a multivitamin is to fill in nutritional gaps, and provides only a hint of the vast array of healthful nutrients and chemicals naturally found in food.
It cannot offer fiber or the flavor and enjoyment of foods so key to an optimal diet. Related Articles. Trending Topics. What Parents Need to Know. Should You Take a Multivitamin? Share this article via email with one or more people using the form below. Send me expert insights each week in Health Essentials News. What do multivitamins do? Who needs multivitamins? How do you choose a multivitamin?
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