Do Vitamin Supplements Help or Hurt Us?

October 22, 2021by Health Desk

Most of us may take supplemental vitamins and common formulations either to make up for not getting enough nutrients from our diet, or with the belief that these supplements will give us an extra health boost to ward off disease. Though it is easier to pop vitamin pills, are they safe and do they deliver on the promise of better health?

Supplementation can be effective in some specific situations, such as folic acid supplementation in pregnant women, or vitamin D and calcium supplementation in older adults who are at increased risk of falls and fractures.

There is very little evidence from scientific studies regarding the benefits of vitamins and mineral supplements in preventing or reversing many chronic diseases. They can also be harmful, especially if taken in high doses for some people. Vitamin supplements are beneficial to people who have specific nutrient deficiency.

Observational studies previously showing health benefits with some supplements turned out, with more rigorous testing, to be not only ineffective, but also risky. Recent studies have shown that high doses of folic acid and B vitamins may increase the risk of cancer. Folic acid and B vitamins were once believed to reduce the risk of heart disease and stroke based on the observational studies. There is not enough evidence to support the hypothesis that these vitamins prevent heart disease and stroke.

Vitamin E, which was once thought to be beneficial for the heart, is now believed to increase the risk of stroke.

The U.S. Preventive Services Task Force (USPSTF) recommends against the use of beta-carotene or vitamin E supplements for the prevention of cancer, heart disease and stroke.

Well established benefits of vitamins

Mother and her child

Folic acid to prevent neural tube defects (birth defects of the brain, spine or spinal cord) in the unborn baby

The natural form of vitamin is folate, which is found in fruits, green, leafy vegetables, cereals, grains, nuts and meats. The synthetic form is folic acid, which is found in supplements and fortified foods. Folic acid is converted into folate before it is absorbed in the body.

The benefits of folic acid supplementation in preventing birth defects in the unborn baby is well established. Folate is required for normal cell division during early development of an unborn baby.

The U.S. Preventive Services Task Force (USPSTF) recommends that all women who are planning or capable of pregnancy take a daily supplement containing 0.4-0.8 mg (400-800 µg) of folic acid.

Vitamin D supplementation in older adults to prevent osteoporosis and fractures

Vitamin D is a nutrient that the body needs for healthy development of bones. It achieves this by absorbing calcium and mineralizing the bone. Vitamin D deficiency is very common in older adults. There is sufficient evidence that vitamin D supplementation in older adults prevents osteoporosis and fractures.

Osteoporosis is a condition where bones become weak and brittle. This occurs when the body makes too little bone, loses too much bone, or both. When the bone becomes brittle there is a high chance of fracture. Increasing age also contributes to the risk of falls and eventual fracture of weakened bones.

Dosage of vitamin D prescribed by your doctor varies from person to person and depends on factors, such as dietary intake, presence of obesity, and sun exposure.

Child in Nature

Vitamin A improves immunity in children living in conditions where dietary intake is not adequate and life-threatening infectious diseases are common

Vitamin A is an antioxidant which consists of preformed vitamin A, called retinol, and the carotenoids, such as beta-carotene. Carotenoids are found in fruits and vegetables, whereas retinol is found in animal products and supplements.

In people who get adequate sources of vitamin A from diet, vitamin A or beta-carotene, supplementation is not recommended due to lack of proven efficacy and possibility of harm. Harm may be in the form of increased risk of reduced bone mass and fractures.

One study conducted in the U.S. showed that the extent of reduction in blood retinol level correlated with severity of the measles illness in children. This suggests taking vitamin A improves immunity in children with inadequate dietary intake.

Vitamin toxicity at high doses

In some people, very low vitamin doses may cause toxicity, because genetic factors may also affect how vitamins are metabolized.

  • Vitamin D may cause high levels of calcium at doses as low as 4000 units/day, the recommended upper limit in some.
  • In adults who are otherwise at high risk due to smoking or exposure to asbestos, beta-carotene (vitamin A) appears to increase the risk of lung cancer.
  • Taking vitamin A during pregnancy can be harmful to the unborn baby at doses as low as several times the recommended dietary allowance.


A well-balanced diet with ample fruits, vegetables, whole grains, beans and legumes, low-fat protein and dairy products provides the necessary amounts of vitamins. Multivitamin supplements are not recommended in this case. A diet rich in fruits and vegetables also contain fiber and thousands of other less well-defined micronutrients.

Multivitamins are generally recommended in situations where there is a risk of vitamin deficiencies from alcohol use disorder, malabsorption disorders (Celiac Disease or Inflammatory Bowel Disease), vegan diet, a history of gastric bypass surgery, and poor-quality diet with low quantities of fruits and vegetables.

Healthy Food

Food sources of vitamins


The best way to get nutrients is through food sources as opposed to supplements. Not all nutrients and substances that are found in healthy foods are present in supplements.

If you decide to take a supplement, consult with your doctor first and thoroughly assess the evidence behind the benefits.