Vitamins are essential for our health. Our bodies cannot function without them. Although most of our vitamins are obtained from our diet, one-third of adults and more than 50% of those over age 55 report taking daily vitamin supplements. People generally believe that vitamins must be safe and that even if they don’t benefit, they are unlikely to cause harm. It’s an unfortunate fact that this does not seem to be true. As a doctor, I am often asked: Which vitamins are recommended? Is it safe to take vitamins? Which vitamins might be dangerous? What are the side effects of taking vitamins? Are there any special points about taking vitamins safely? Read on—and to ensure your health and the health of others, don’t miss these Signs. Your Illness is Coronavirus in Disguise.
1 Which Vitamins are Recommended? The truth is that most people get all the vitamins they need from their diet. If your body has enough vitamins, you will excrete them in your urine and feces if you take extra vitamins. There is generally no need to take vitamin supplements. However, there are a few exceptions: Pregnant women should take 400 mcg of folic acid daily. This is to help prevent the baby from developing neural tube defects (e.g., spina bifida).Vitamin D – The current recommendation for UK adults to at least is to take ten mcg (400 IU) per day of vitamin D. This is because low levels of vitamin D are widespread. This advice was issued in April at the start of the COVID-19 pandemic because vitamin D is made in the skin in sunlight, and people were only advised to go outside to exercise for 1 hour per day.
As winter is approaching and the days are becoming shorter, it may be wise to top up vitamin D levels because all respiratory infections are more common in winter. Vitamin D is important in our immune defense. 2 Is it Safe to Take Vitamins? A 2016 review in the Advanced Pharmaceutical Bulletin reviewed all the good quality randomized controlled trials on vitamins between 1993 -2015. The authors concluded that taking high doses of vitamins A, E, D, C, and folic acid did not always help prevent disease and, in some situations, could be harmful. They proposed that vitamins should only be issued under the control of a trained pharmacist. Read on to learn which vitamins might be dangerous—and when? 3 Vitamin E is a powerful antioxidant. Antioxidants are important molecules as they have many anti-cancer effects on the body.
However, their effect is complex, and too many can be harmful. There has been no significant benefit in many studies where vitamin E has been given to patients to reduce the incidence of cancer, cardiovascular disease, or death. Some studies have looked at the effect of vitamin E on preventing prostate cancer or lung cancer and have even found this led to a small increase in risk. There seem to be risks associated with taking vitamin E at high doses. 4 Vitamin C is also a potent antioxidant with many properties, highly beneficial for health. However, many large studies have failed to show that taking vitamin C supplements affects reducing cardiovascular disease, cancer, or death. Many people believe high doses of vitamin C can prevent upper respiratory infections. However, this does not appear to be the case. A 2013 Cochrane data review included 29 trials, and 11, 306 participants failed to show that vitamin C supplements prevented the common cold. Vitamin C supplements may even be harmful.
In one 2004 study, vitamin C supplements in diabetic women increased mortality from cardiovascular disease. Adverse effects from vitamin C are only seen in those taking supplements. They are not seen when large amounts of vitamin C are ingested in food. 5 Vitamin A—also known as retinol—is largely derived from beta-carotene, the red/orange pigment in many vegetables such as carrots. Vitamin A is another powerful antioxidant. Studies have shown that a good dietary intake of vitamin A reduces lung, breast, pancreas, and bladder cancer. However, taking vitamin A supplements does not seem to have the same effects. For example, in the Beta Carotene and Retinol Efficacy Trial (CARET), 18,000 current or recent smokers, and asbestos workers, were randomly assigned to vitamin A or placebo and followed up.
After six years, there was a 28% increase in lung cancer and a 17% increase in mortality in the vitamin A group. In pregnant women, high doses of vitamin A have been shown to increase the risk of neural tube defects by a factor of 3.5. Vitamin A is now regarded as teratogenic. Although vitamin A is important for bone growth, excess vitamin A is not necessarily beneficial. Vitamin A deficiency is associated with poor bone growth, but extra vitamin A results in increased bone resorption (bone clearance) with fragile bones and increased fracture risk. 5 Folic Acid This is a water-soluble B vitamin. Folate deficiency increases the risk of developing new cancer, but excess folate also increases cancer risk by increasing the rate of cancer cell growth. In one 2009 Norwegian study, 6837 patients with cardiovascular disease were randomly assigned to either folic acid supplements or a placebo and followed up for nine years.
The folic acid group showed a significant increase in cancer outcomes and mortality compared to those on the placebos. 6 Vitamin D At one time, experts believed vitamin D supplements could reduce the risk of colorectal cancer and bowel polyps. However, a large 2006 randomized trial of 36,282 postmenopausal women who took calcium and vitamin D supplements for seven years did not reduce colonic cancer incidence. In the UK, calcium and vitamin D supplementation is recommended for perimenopausal or postmenopausal women at risk of osteoporosis. It has been shown to improve bone mineral density and prevent fracture. 7 What are the Side Effects of Taking Vitamins? Although most vitamins are well tolerated, side effects are possible with any medication.
Always check with your healthcare provider if you have chronic medical conditions or take any other regular medication before taking new tablets, including vitamin supplements. If you have any signs of an acute allergic reaction—acute anaphylaxis—after swallowing a vitamin tablet, you must seek urgent help immediately. Vitamin E – Side effects are rare. These include headaches, dizziness, abdominal cramps, diarrhea, tiredness, and skin rashes. Rarely can vitamin E cause bleeding problems with nosebleeds or bleeding gums. Vitamin C – Side effects are rare. These include high doses of headaches, flushing, nausea, vomiting, dizziness, and migraines. High doses of vitamin C may increase uric acid levels leading to kidney stones. Vitamin C may raise blood sugars in diabetic patients. Vitamin A – Side effects are rare. These include headache, fatigue, lethargy, abdominal pain, loss of appetite, and vomiting.