How vitamin toxicity is hurting your health

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vitamin c.

Shutterstock: Image/Umpaporn

In case you didn’t know, vitamin overdosing is a thing. Weird, right? You wouldn’t think you could overdose on something that’s supposed to be healthy for your body. But like everything else, vitamins need to be consumed in moderation. The technical term for an overdose of vitamins is hypervitaminosis. Simply put, your liver can’t filter through it all.

We tend to assume that all vitamins are healthy for our bodies. And while vitamins do have the effect of nurturing our bodies, they can have negative side-effects when not consumed appropriately.

Hypervitaminosis primarily affects fat-soluble vitamins, as they are stored longer in your body. The most common fat-soluble vitamins are known as the “DEKA” vitamins (for obvious reasons): Vitamin D, E, K and A. However, hypervitaminosis can also occur with water-soluble vitamins such as the B vitamins and vitamin C.

While doing some research in order to find out more about vitamin toxicity and how we can appropriately nurture our bodies, I started to notice a theme: there is a ton of misleading and non-uniformed information being spewed across the internet about vitamins. So rather than feed you a line here, we at Wably interviewed licensed dietitian Melissa Giovanni of Allison Nutrition Consulting in Nashville, Tennessee for some expert and concise answers to the many questions we have regarding vitamins and their appropriate uses.

So let’s start with the basics.

What vitamins are the most commonly used by adult women?

Multivitamins and mineral supplements are the most commonly used supplements, which contain many different vitamins and minerals in one capsule. “A lot of times supplements are looked at as a means to all health concerns when in reality our nutrition is more important.” Explains Giovanni. “Supplements should be used in a way that their name describes, as supplementation to a healthy and well balanced diet.”

According to the federal government’s 2015-2020 Dietary Guidelines for Americans, “nutritional needs should be met primarily from foods. Foods in nutrient-dense forms contain essential vitamins and minerals and also dietary fiber and other naturally occurring substances that may have positive health effects. In some cases, fortified foods and dietary supplements may be useful in providing one or more nutrients that otherwise may be consumed in less-than-recommended amounts.”

So rule of thumb: We should be trying to get our nutritional needs met mostly by the food that we eat. Vitamins are not meant to replace a good diet, but rather they should be used to supplement our diet when what we are eating isn’t filled with the recommended nutrients that we should be receiving from a healthy diet.

“Women also typically take calcium and vitamin D supplements eventually in their lives,” states Giovanni. “This doesn’t mean they are overused, however being mindful of how much of the vitamin is in the supplement and how much you are getting from your diet as to not exceed upper limits.”

Would you say vitamin toxicity is more common than most people realize?

“Although most vitamin toxicity is rare, it does happen.” Giovanni stated. “In recent years, due to the increasing awareness of vitamin D, cases of vitamin D toxicity are occurring from individuals taking high dose supplements of Vitamin D leading to nausea, vomiting, poor appetite, and weight loss.”

As previously stated, we know that vitamin toxicity is more common in the fat-soluble vitamins (DEKA.) This is due to these fat-soluble vitamins being stored in fat, while water-soluble vitamins (which include all of the B vitamins and vitamin C) are less likely to cause toxicity. Your body easily absorbs water-soluble vitamins and the kidneys remove the vitamins that are in excess and excretes them through urination.

What are some symptoms of hypervitaminosis?

The symptoms surrounding hypervitaminosis will differ depending on the vitamin itself. So we’ve made a little cheat sheet on what you can expect from overdosing on these vitamins:

Vitamin D

Some symptoms of Vitamin D hypervitaminosis include nausea, vomiting, poor appetite, constipation, weakness, weight loss, confusion, heart rhythm problems, deposits of calcium and phosphate in soft tissues.

“When large doses of vitamin D are taken, the liver can produce too much of a chemical called 25(OH)D.” Explains Giovanni. “This chemical when too high can cause high levels of calcium to develop in blood. High blood calcium is called hyperkalemia, symptoms of hyperkalemia include: nausea, vomiting, poor appetite, feeling very thirsty, passing urine often, constipation or diarrhea, abdominal pain, muscle weakness or pain, bone pain, feeling confused and tired. Excessive sun exposure has been found to not contribute or cause vitamin D toxicity, as well.”

Vitamin E

Research has not found any adverse effects from high intakes of Vitamin E through foods. Although, high doses through supplements has been found to cause hemorrhage and changes in blood coagulation in animals.

Vitamin K

Vitamin K has a low potential for toxicity, and there isn’t much research out there to support the claims on the negative effects. Although it still can raise concern if taken to excess for people with certain medical conditions or who are taking particular medications.


If you consume a diet high in vitamin K-rich foods, or if you are taking a supplement of vitamin K, consult your doctor prior to taking medications to help prevent clotting to avoid possible complications. Vitamin K can also adversely interfere with some antibiotics, as well as certain weight-loss drugs, such as olestra. In the case of the latter, these weight loss drugs inhibit your body’s fat absorption ability, rendering it more difficult for your body to absorb, or retain, vitamin K.

Vitamin A

Excessive intake of preformed vitamin A can have significant toxic side effects on the body, dependent on the size and rapidity of the excess intake. Symptoms would include nausea, vomiting, headache, dizziness, burred vision, clumsiness, birth defects, liver problems, and possible risk of osteoporosis. This typically occurs from too much  vitamin A from supplements rather than dietary intake of foods.

B Vitamins

B3 (Niacin): Symptoms of consuming too much B3 can include flushing, redness of skin, and an upset stomach.

B6 (Pyridoxine): High intakes of vitamin B6 from foods has not been found to have adverse effects. However, high doses of supplementation has been found to cause nerve damage to the limbs, numbness, trouble walking, pain, neuropathy, and nausea.

Riboflavin (Vitamin B2): “There is not an established upper limit for Riboflavin due to no adverse effects being reported. This can be due to riboflavin’s solubility and capacity to be absorbed in the GI tract. Although, no adverse effects have been reported it is possible that high intakes could have adverse effects.” Explains Giovanni.

Thiamin (Vitamin B1): There have not been reported adverse effects from high intake of thiamin, as the body excretes excess amounts of thiamin in the urine. Although no adverse effects have been reported, there could be adverse effects to excessive intakes of thiamin.

Vitamin B12: B12 has low potential for toxicity, and no adverse effects have been associated with excess vitamin B12 intake from food or supplements.

Vitamin C 

Hypervitaminosis of vitamin C has a low toxicity occurrence and it not believed to cause serious adverse effects with high intakes. The majority of symptoms of high intakes of vitamin C are upset stomach, diarrhea, and possible kidney stones.

What are the treatment options for hypervitaminosis?

The treatment options for hypervitaminosis will differ based upon the symptoms and possible damage to the body that could have occurred.

“The first step in treatment would be to stop taking any new supplement or vitamin the minute you notice something unusual happening in your body, and contact your medical provider for evaluation. A physician can address hypervitaminosis symptoms and possible further damage to the body.” Explains Giovanni. “In some cases the toxicity could be severe and going to the emergency department may be necessary.”

What type of demographic is at higher risk for vitamin deficiencies?

While the concern for hypervitaminosis is very real, it is also just as important to note that many women really do have vitamin deficiencies and therefore need to be making sure they are getting the proper daily intake for certain vitamins they may be lacking.

Giovanni gave us a list of the demographic of women that need to be extra cautious that they are getting the appropriate amount of vitamins and minerals:

  • Women who eat a highly processed diet, low in fresh vegetables and fruits
  • Vegetarian or vegan individuals
  • Individuals whom are underweight
  • Women of reproductive age
  • Women over 65 years of age

Sounds all inclusive, doesn’t it? What we can gather from this list is that all women need to be very aware of what their bodies need more of or less of, and the only way to truly do that is to be in tune with your body’s internal and external health. It also doesn’t hurt to consult a dietitian or nutritionist every once in a while to make sure you are on the right track.

What particular vitamins are important for women to consume?

The Recommended Dietary Allowances (RDA) vary different from vitamin to vitamin, according to the National Institutes of Health Office of Dietary Supplements. Giovanni gave us another cheat sheet for the recommended daily intake for these important vitamins, perfect for snapping a screenshot of and before you hit your nearest vitamin supplier:

Vitamin A: Females ages 19+ = 700 mcg RAE (Retinol Activity Equivalent)

Vitamin D: Females ages 19-70 years/pregnancy/lactation = 600 IU (15 mcg); Females 70+ years = 800 IU (20 mcg)

Vitamin E: Females ages 14+ years and during pregnancy = 15 mg (22.4 IU); with lactation = 19 mg (28.4 IU)

Vitamin K: Females ages 19+ years/during pregnancy and lactation = 90 mcg

Vitamin B6 (Pyridoxine): Females ages 19-50 years = 1.3 mg; 50+ years = 1.5mg; during pregnancy = 1.9 mg; during lactation = 2.0 mg

Vitamin B2 (Riboflavin): Females ages 19+ = 1.1 mg; during pregnancy = 1.4 mg; during lactation = 1.6 mg

Vitamin B1 (Thiamin): Females ages 19+ = 1.1 mg; during pregnancy and lactation = 1.4 mg

Vitamin C: Females ages 19+ years = 75 mg; during pregnancy = 85 mg; during lactation = 120 mg

Where can we find these vitamins and minerals naturally in foods?

As Giovanni said earlier, it is best to consume our vitamins and minerals naturally through a healthy diet, rather than solely through supplements. Unfortunately, few foods in nature contain vitamin D. “Salmon, tuna, and mackerel flesh are great sources of Vitamin D, as well as fish liver oils.” Explains Giovanni. “Smaller amounts of vitamin D can be found in beef liver, cheese, and egg yolks. Foods that are fortified with vitamin D include dairy products, orange juice, and cereals.” So if you are lacking in vitamin D, these are a few good places to start.

Vitamin A is a little easier to be found. Giovanni’s list of vitamin A-rich foods are probably already somewhere in your kitchen! “Sweet potatoes (particularly the skin), beef liver, spinach, carrots, pumpkin, cantaloupe, red peppers, mangos, apricots, broccoli, black-eyed peas, tomato juice are all great sources are vitamin A,” explains Giovanni.

Vitamin E is easily found in nuts, seeds, vegetable oils, green leafy vegetables, and fortified cereals – which are all easy to incorporate into most diets. Similarly, vitamin K is found in green leafy vegetables, vegetable oils, pumpkin, soybeans, blueberries, meat, dairy and eggs.

Most fruits and vegetables are high in vitamin C, including citrus fruits, tomatoes, potatoes, kiwi, broccoli, strawberries.

B vitamins are found in many different kinds of foods. Chickpeas, beef liver, tuna, salmon, chicken, fortified breakfast cereals, potatoes, turkey, and bananas are all foods that are rich in vitamin B6. Eggs, organ meats (kidney and liver), lean meats, milk, green vegetables, and fortified breakfast cereals are rich in vitamin B2. Vitamin B12 is found in animal products, including fish, meat, poultry, eggs, milk, and milk products, fortified breakfast cereals, and some nutritional yeasts (this is why many vegetarians and vegans need to take a B12 supplement). Vitamin B1 can also be found in fortified whole grains, meat, and fish.

Several independent organizations offer quality testing of supplements and these supplements will show a seal of approval. This assures that the product was properly manufactured, contains the ingredients listed on the label, and does not contain harmful levels of contaminants. These organizations are U.S. Pharmacopeia, ConsumerLab.com, and NSF International. These seals do not guarantee that a product is safe or effective.

It is crucial to inform your healthcare providers about what supplements (i.e. vitamins, herbs, minerals) you are taking as many can interact with prescription medications. Some examples of this include vitamin K reducing the ability of the blood thinner Coumadin to prevent blood from clothing, St. John’s Wort can increase and speed up the breakdown of many drugs including antidepressants and birth control, which decreases their effectiveness.

“I would encourage women to aim for the recommended 5-9 servings of fruits and vegetables per day, make half their grains whole grains, choose lean meats, and get healthy fats from foods like nuts, avocados, and oils to get their vitamins and minerals from food.” Explains Giovanni. “However, in our busy society it can be hard for that to always occur and a multivitamin can be an ‘insurance policy’ used in case not all nutrients are being consumed regularly. Some vitamins and minerals that tend to lack in the typical American diet are calcium, potassium, dietary fiber, and vitamin D.”

Meet the Expert


Melissa Giovanni is a registered, licensed dietitian with her Master’s degree from Eastern Michigan University, and a dietitian at Allison Nutrition Consulting in Nashville, Tennessee that works with individuals with a broad range of nutrition and related concerns. They take into account many aspects of their clients lives, including medications and supplements, health histories, goals and food preferences, meal patterns, skills, learning styles, lifestyle and interests as they determine with their clients what strategies and support to recommend.

They specialize in working with people who struggle with gastrointestinal issues, food sensitivities, and disordered eating. They enjoy working with people who simply want to look at making some changes in their diet and who want support in doing so.