Too much of a good thing isn’t better, and that applies to vitamins too. If you get your vitamins naturally from food, there are fewer risks of getting too much of any one nutrient or vitamin. However, if you take supplements, which are concentrated sources of a vitamin or vitamins, the risk of getting too much is greater.
Most people don’t realize that you can overdose even on things that are healthy in reasonable doses. In fact, there are cases where supplemental vitamins can do more harm than good. Curious as to which vitamins you can get too much of? Here are four to be aware of.
Vitamin A
Vitamin A is essential for the growth and repair of body tissues, especially bone, teeth, skin. and hair. It also plays a critical role in night vision. There are 5 main types of vitamin A: retinol, retinal, retinoic acid, retinyl ester, and beta-carotene. Beta-carotene is the plant-based form found in orange fruits and vegetables, and your body is only able to convert a certain percentage of beta-carotene in plant-based foods to vitamin A.
Why can you get too much? Vitamin A is a fat-soluble vitamin, meaning your body stores excess vitamin A, mainly in the liver. Over time, vitamin A levels can build up and cause liver toxicity. This could come from taking large doses of vitamin A in supplement form.
Even some foods contain such large amounts of vitamin A you shouldn’t eat them every day. For example, beef liver is one of the richest sources of vitamin A. Early explorers of the Arctic ate polar bear liver, and some died from vitamin A toxicity. The risk is only for preformed vitamin A in animal-based foods. It would be difficult to eat enough beta-carotene from food to develop toxicity.
Vitamin D
Bone health and muscle function are both enhanced by vitamin D. Additionally, it helps the body absorb calcium. Because vitamin D is a fat-soluble vitamin, it could lead to toxicity if you take a lot of it for a prolonged period. A high vitamin D level can lead to high calcium levels in the blood and kidney stones. Early signs of vitamin D toxicity include nausea, vomiting, and frequent urination.
If you take a high-dose vitamin D supplement, to correct a deficiency, make sure your healthcare practitioner checks your vitamin D level regularly. Sunlight is also a source of vitamin D for humans. However, there are mechanisms that prevent vitamin D toxicity from sun exposure. The main source of toxicity is taking high-dose vitamin D supplements.
Vitamin B6
Although vitamin B6 is water-soluble, you can still develop vitamin B6 toxicity if you take high doses. Yet you need this vitamin for protein metabolism, to make neurotransmitters that affect mental health, and the production of DNA. Food sources include potatoes, bananas, whole grains, liver, fish, chicken, and other organ meats. Cooking reduces the amount of vitamin B6 in foods.
How much vitamin B6 do you need each day? The recommended intake of vitamin B6 is 1.3 – 1.7 milligrams daily. The upper limit of safety is 100 milligrams of vitamin B6 per day, although it’s uncommon to experience adverse effects from taking less than 200 milligrams of vitamin B6 daily. However, going over the upper safety limit of 200 milligrams daily can lead to neuropathy or inflammation of the nerves. Symptoms might include tingling in the hands and feet, mood changes, seizures, fatigue, or mood changes.
Vitamin E
Vitamin E is an antioxidant vitamin that helps protect cells against oxidative stress from free radicals. Like vitamins A and D, vitamin E is fat-soluble and hard to eliminate from the body. Vitamin E is most abundant in seeds, almonds, vegetable oils, wheat germ, and leafy green vegetables, but it would be hard to consume too much through food alone. However, taking high doses of vitamin E in supplement form can lead to vitamin E toxicity.
How much is too much? The upper safe limit, according to the National Institute of Health, is 1,000 milligrams of vitamin E daily while the recommended daily intake is 10 to 15 milligrams daily. However, studies show there is no benefit to taking vitamin E as a supplement unless you’re deficient.
In fact, some studies show that taking high doses of vitamin E in supplement form increases the risk of serious bleeding, such as bleeding into the brain. Other studies show taking even lower doses in supplement forms may increase the risk of prostate cancer. That’s why it’s best to get vitamin E from food sources such as nuts, seeds, and leafy greens.
The Bottom Line
If you eat a varied diet, you’re not at risk of overdosing on vitamins from food alone, It’s unlikely that you’ll develop vitamin toxicity from a multivitamin either. Most multivitamins are balanced enough that you won’t get a super-sized dose of any of these vitamins. The risk is highest if you take a high-dose supplement of any of these vitamins.
Vitamins are essential to your health and wellbeing, but the food we eat comes with a wider range of vitamins and nutrients than we can get from a supplement. If you’re worried about meeting your body’s vitamin requirements, the best approach is to eat a variety of whole, nutrient-dense foods. Make sure the foods you choose are real foods, not ultra-processed fare and junk food. Ultra-processed foods are often too low in key nutrients for good health.
References:
- National Institutes of Health. “Vitamin A”
- National Institutes of Health. “Vitamin D”
- National Institutes of Health. “Vitamin E”
- National Institutes of Health. “Vitamin K”
- Katan MB. [How much vitamin B6 is toxic?]. Ned Tijdschr Geneeskd. 2005 Nov 12;149(46):2545-6. Dutch. PMID: 16320662.
- com. “Getting Too Much of Vitamins And Minerals”
- com. “Health benefits and sources of vitamin K”
- org. “Beta-carotene”
- “Vitamin E: Uses, Benefits & Side Effects – Drugs.com.” 01 Apr. 2021, https://www.drugs.com/vitamin_e.html.
- “Taking Too Many Vitamins? Side Effects of Vitamin Overdosing.” https://www.webmd.com/diet/guide/effects-of-taking-too-many-vitamins.
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