We’ve all heard the saying, “Too much of a good thing is bad for you.” But what about when it comes to vitamins? Can you ever really overdo them?
“Yes, absolutely,” said Dawn Gerber, PharmD, a clinical ambulatory pharmacy specialist with Banner Health. “Basically, there are two types of vitamins: water-soluble and fat-soluble. Although your body can excrete large amounts of water-soluble vitamins, it holds onto fat-soluble vitamins, which can be toxic at high levels."
Water-soluble vitamins, like vitamin C and B-complex, are carried to the body’s tissues and aren’t stored in your body. Fat-soluble vitamins, like A, D, E and K, are absorbed along with fats in your diet and are stored in your body’s fatty tissue and in the liver.
“These get caught in our fat, the non-muscular parts of our bodies,” Dr. Gerber said. “The more supplements we take at high doses, the more that accumulates and isn’t flushed out.”
While it’s hard to overdose just eating these vitamins naturally with a well-balanced diet, vitamin supplements can have negative ramifications.
Here’s what you need to know to avoid overdoing it in the supplement department.
Watch out for these fat-soluble vitamins: A, E and K
Here are details about vitamins A, E and K and the symptoms of overdose to look out for.
Vitamin A is a fat-soluble nutrient that is naturally present in many foods, like beef, eggs and many fruits and vegetables. An overdose of this vitamin can lead to problems with confusion, hair loss, liver damage and bone loss. It can also cause an increased risk for death and lung-associated issues for those who have a history of smoking—particularly female smokers.
Vitamin E is a fat-soluble nutrient found naturally in foods and added to some fortified foods that can help protect cells from damage caused by free radicals, such as air pollution. But taking too much of this supplement can increase your risk for bleeding and bleeding in the brain.
Vitamin K is a fat-soluble nutrient that’s important for blood clotting, healthy bones and other bodily functions. It’s rare that you’ll overdose on vitamin K by eating things like broccoli. But in supplement form, it can induce blood clots, which can lead to heart attacks and strokes, if you take too much.
What about vitamin D?
You may have noticed we left vitamin D off this fat-soluble list, and there is a good reason (or two for that). “The reason for this is that we don’t typically see overdose with vitamin D as much,” Dr. Gerber said. “The data hasn’t shown detrimental effects of high doses. In addition to this, many Americans are actually deficient in the vitamin as well.”
Don’t overdo vitamin C and zinc either
With cold season, flu season and the COVID-19 pandemic, many people load up on vitamin C and zinc thinking they can fight off—and even prevent illnesses. But the verdict is still out on their potential benefits—especially when it comes to COVID-19.
“Vitamin C is especially hot right now with COVID-19,” Dr. Gerber said. “There’s currently no strong data that shows vitamin C and zinc help with cold viruses. And the verdict is still out on COVID-19, mostly because it hasn’t been around long enough to know.”
Overdose symptoms for vitamin C and zinc
Vitamin C is generally safe, but in large doses (anything over 2,000mg), it can cause diarrhea and nausea. High doses can also result in falsely elevated blood glucose readings, which can be problematic for diabetics. Low blood glucose can cause them to feel shaky, sweaty and can even lead to seizure or a loss of consciousness. “Diabetics use their home glucose monitor and their glucose level looks fine, but the high dose of vitamin C is masking the real low blood glucose reading,” Dr. Gerber said.
Oral zinc can also cause gastrointestinal problems and a host of other problems if taken long-term, especially in high doses (anything over 40mg). High levels of zinc can cause a copper deficiency, taste disturbances, hematologic and neurological effects and may interact with some medications and antibiotics.
“For example, if you’re taking zinc with an antibiotic, you won’t get 100% of the benefit of the antibiotic,” Dr. Gerber said. “That’s because zinc can bind itself to the antibiotic and weaken the medication’s effectiveness. This can be very frustrating for patients who don’t understand why they aren’t getting better.”
Before you pop a vitamin or supplement, contact your doctor
While you might feel like you are low in this or that, don’t go with your gut. You may actually be deficient in something else completely.
Schedule an appointment with your primary care doctor to assess your overall health and if you may be lacking in certain vitamins. As a general tip: It’s important to check in at least once a year with your doctor. Your doctor may recommend certain over-the-counter supplements or suggest simple diet adjustments that can help get you back on track.
You’ll also want to talk to your doctor or a pharmacist to see if any vitamins interact with any medications you are taking.
“When it comes to taking any medications, pharmacists and doctors consider, ‘Is this the right drug for the right patient for the right issue?’ and the same holds true with vitamins,” Dr. Gerber said. “You want to make sure the vitamins you are taking are necessary and right for you."
To find a Banner Health specialist near you, contact bannerhealth.com.