Vitamins for preventive health
Our weather in the Pacific Northwest is filled with rainy and cloud-stricken days, making vitamin deficiency a hot topic at local primary care clinics, especially during the winter months.
Many people take supplements as an attempt to round out their diets. The fact of the matter is, the vast majority of the U.S. population receives adequate levels of vitamins and micronutrients in their diet.
Surprisingly, while ubiquitous in your local pharmacy and grocery stores, there are only a handful of vitamins that have actually been shown to have positive effects on our health. Even then, these positive effects are only present for specific populations under specific circumstances.
So where do you start? Here are the some vitamin myths and facts I share with my patients that can help you make an informed decision next time you check out the vitamin aisle.
What is a vitamin?
A vitamin is an organic compound necessary for metabolism in humans that can only be obtained from the diet. This excludes some micronutrients such as calcium and iron, which are minerals that are also important elements that can cause problems if deficient in a person’s diet.
Vitamins are a small component of the broader category of supplements, which is a more general term for over-the-counter products purported to have health benefits.
Vitamin D is the latest vitamin to receive a lot of favorable press, both in the popular press and in the scientific discourse. Deficiency of vitamin D has been linked to everything from depression to fall risk in the elderly to osteoporosis.
The recommended daily allowance for vitamin D for adults up to 70 years of age is 600 IU and increases to 800 IU for those older. In general, if you live in an area such as Seattle that doesn’t get much sunlight during the winter months, it might be a good idea to take this supplement (400 IU daily).
Vitamin D is found in milk, fortified cereals, fatty fish, as well as liver. Anything beyond a dose of 4000 IU can cause too high of levels of calcium in the blood stream.
There are specific populations of people — such as strict vegans, those with a nutrient malabsorption syndrome or those who have little variety in their diet — who can sometimes become deficient in vitamin B12. Deficiency can cause anemia (low blood counts), memory problems and neurologic symptoms.
Vitamin B12 is found in such foods as liver, milk, meat and fish.
The recommended dosage for vitamin B12 is 2.4 mcg each day for the average person and is a little higher for pregnant or lactating women.
The other special population that needs particular supplementation is women of child-bearing age. Folic acid is an important vitamin for the development of the fetal neurologic system. Taking folic acid helps prevent neural tube defects in the fetus.
Because the critical development occurs in the first four weeks of pregnancy, I recommend this vitamin for women who are planning on becoming pregnant.
Folic acid is found in leafy green vegetables, fruits, cereals, grains, nuts and meats.
Vitamins C, A, E
Beyond the above vitamins, the vast majority of the other vitamins have not been found to be conclusively beneficial for the average American to take. For example, vitamin C has been touted as a vitamin to help boost the immune system.
Studies have not shown that taking vitamin C supplements at the onset of cold symptoms shortens the duration of the cold. Randomized controlled trials of vitamin A have not been found to prevent cataracts or vision loss from macular degeneration. To date, there have not been any studies showing that vitamin supplementation can prevent cancer or cardiac disease.
In fact, vitamin E has been shown in studies to actually increase the rate of lung cancers in those who have risk factors for lung cancer, such as smoking history or asbestos exposure.
Most vitamins found in multivitamins are not likely to have much of an effect on the average person’s health. Sometimes, it does make sense to take a multivitamin if it does contain the dosage of a specific vitamin such as vitamin D or folate that you are looking for. Sometimes, you may find it more economical than taking an individual supplement.
Be careful, however, to make sure that your multivitamin does not contain more than 400 units of vitamin E as there is some evidence that high doses of vitamin E supplementation can cause serious health issues.
The bottom line is there really is only a select few vitamins that have been shown to have benefit, and more is definitely not always better for you.
All in all, if you eat a relatively varied diet, you do not need to worry about taking a lot of supplements. If you’re interested in learning more, make an appointment with your primary care provider to see which vitamins are right for you.