Vitamin Overdose: Why Proper Dosage Matters

Many of us have a daily routine. We wake up, take a shower, eat breakfast, etc. Of course, routines vary. Taking vitamins is also among the more popular daily routines for many people. 

Some use labeled vitamin holders to help give them their daily reminder, others wing it and simply take their vitamins whenever the thought crosses their mind. 

For many people, vitamins are often put in a different category outside of medication. Due to this fact, forgetting to take them is not seen as a big deal. 

If I forget to take them today, I’ll just double up tomorrow. 

They are just vitamins, after all — what’s the harm? Aren’t vitamins simply an extra shot of nutrients? You can’t have too much of a good thing. Right?

Contrary to popular belief, there is such a thing as vitamin overdose — proper dosage does matter. 

Vitamins and Why We Take Them

In some cases, excess vitamin consumption can have harmful effects on your health. That seems contradictory to most people since vitamins are often used as a nutrient supplement, but it’s true. 

But why do we even take vitamins in the first place? 

Vitamins, More Than a Supplement

Most people are fully aware that vitamins are not born on supplement aisle shelves. Generally, vitamins are consumed naturally through the foods we consume. The body cannot produce essential vitamins naturally on its own, or at least in the amounts needed. Certain vitamins, like vitamin D, can be made by the body in small amounts.

But what are they exactly? Simply put, vitamins refer to a group of organic substances that plants and animals produce. These substances are required for various processes in the body, e.g., metabolism, cellular function, growth and development, and more. 

Currently, 13 vitamins are recognized as “essential.” This simply means that they are required for our bodies to function normally. Here are the 13 essential vitamins:

  • Vitamin A
  • Vitamin C
  • Vitamin D
  • Vitamin E
  • Vitamin K

 B-Complex Vitamins 

  • Vitamin B1 (thiamine)
  • Vitamin B2 (riboflavin)
  • Vitamin B3 (niacin)
  • Vitamin B5 (pantothenic acid)
  • Vitamin B6
  • Vitamin B7 (biotin)
  • Vitamin B9 (folate)
  • Vitamin B12

 Water-Soluble and Fat-Soluble Vitamins

These essential vitamins are broken into two groups: Water-soluble and fat-soluble vitamins. This determines how they are absorbed and stored by the body. 

Vitamin C and the B-complex vitamins are considered water-soluble. They are easily absorbed and dissolved in the body. Normally, excess amounts are excreted through the urine. 

Vitamins A, D, E, and K are considered fat-soluble. Fat-soluble vitamins are dissolved in fat and are stored in the body, e.g., liver and fatty tissues. Since excess amounts are stored and not excreted like water-soluble vitamins, toxicity can be a genuine concern. 

What Do Vitamins Do For Our Body?

We don’t have time to get into the specifics of every vitamin, but as was stated, vitamins are required for various processes throughout the body. People can have different vitamin requirements depending on age and sex. 

Here are a couple of examples of some popular vitamins and their role in the body:

Vitamin A

Vitamin A is considered a fat-soluble vitamin. It is well-known for being a source of beta carotene, which is a type of carotenoid. Due to this fact, its popular claim to fame is in the area of eye health. However, it is also essential for the immune system, bone formation and growth, and skin health. 

Good sources of vitamin A can be found in carrots, kale, sweet potatoes, and beef liver. It is also found in many multivitamin supplements but can also be found in isolation. Since the required amounts are often consumed through the diet, deficiencies are rare. 

Vitamin D

Vitamin D is another fat-soluble vitamin. One of vitamin D’s many roles has to do with bone health and the healthy mineralization of bone. It does this by helping aid calcium absorption. 

Though vitamin D can be found in food — oily fish, liver, and dairy — the body’s main source is sunlight. Our body has a unique ability to produce vitamin D when it is exposed to sunlight. Deficiencies can arise, especially among those whose sunshine intake is limited. 

Why We Take Vitamin Supplements

The reasons for taking vitamins as a supplement are numerous. Vitamin supplementation can be recommended or even prescribed by a healthcare provider — due to deficiencies or other health issues. 

Some people take them due to dietary restrictions; e.g., many who prescribe vegetarian or vegan diets must supplement with B vitamins, like B12, since they do not consume animal proteins. 

Another example is supplementing B9 (folic acid) during pregnancy, as it can help support normal fetal development. 

At the end of the day, vitamins are taken for various reasons, but proper nutrition and overall wellness is the main aim. 

But can vitamin overdose actually occur? Simply put, yes. 

Vitamin Overdose

There can be too much of a good thing. Vitamin overdose is rare, but it can happen. Typically, vitamin overdose occurs when vitamins are ingested in excess — above the daily recommendation. Vitamin D toxicity is more often caused by large doses of vitamin D supplements than diet or sun exposure.

Generally, vitamin overdose also depends on the type of vitamin. As stated, water-soluble vitamins are not stored in the body. Under normal conditions, when there is an excess, they are simply excreted through the urine as a waste product. However, vitamin B6 has been known to cause some health risks when consumed in excess. 

Vitamin overdose is more common among fat-soluble vitamins. As discussed, these vitamins are stored in the body. If excess amounts rise then, toxicity could become an issue. Generally, however, vitamin D intoxication often results from taking higher than prescribed or over-the-counter formulations.

Because vitamin D is associated with bone, muscle, and heart health, it is essential to note that people who take megadoses of vitamin D are more prone to bone fractures and heart issues.

Here is one example:

According to medical experts, the health risks from excess amounts of vitamin A can range from mild to severe, and in some cases, even life-threatening. Symptoms of a vitamin d overdose can lead to hypercalcemia or high blood calcium levels,  creating dizziness, nausea, calcification of soft tissue, frequent urination, excessive thirst, dehydration, weakness, confusion, agitation, irritability, and severe cases, kidney failure, stupor, or coma. 

Abdominal pain, vomiting, constipation, and polyuria are additional symptoms that can manifest from high doses of vitamin d. In rare cases, extremely high amounts of vitamin d intake are linked to prostate cancer, pancreatic cancer, and increased mortality.

All in all, it's fairly difficult to overdose on vitamins as long as you follow the directions on the supplement labeling. If you're worried, you may be taking too much of a vitamin, consult with your primary care provider.

Dosage Matters

So, what is the moral of the story? Well, vitamin overdose can happen, though it is often rare. It usually occurs when vitamins are taken in excess as a supplement. 

This is why proper dosage matters. The supplement label is there for a good reason. 

The Institute of Medicine has set nutrient recommendations, and intake amounts for dietary supplements — where all the recommended daily intake for vitamins are listed. 

They have set forth three value areas for nutrient intake for healthy people; they vary by age and sex. 

  • Recommended Dietary Allowance (RDA): This refers to the average daily level of intake that is sufficient to meet nutrient requirements in healthy people. 
  • Adequate Intake (AI): When research or evidence is insufficient to set an RDA, AI is used to set an assumed nutritional level. 
  • Tolerable Upper Intake Level (UL) refers to the maximum daily intake level that is unlikely to cause health effects. The point: This threshold should never be exceeded. 

You'll often notice that the amounts of vitamins included in supplements are much higher than the RDA value -- this is to help make up for any of the vitamins that may be lost to metabolism as your body processes the supplement.

Foods to Consider for Vitamin D Deficiency

  • Egg yolks
  • Salmon 
  • Cod liver oil


Vitamins are essential to our body to maintain normal function. Adequate amounts of vitamins are often consumed through diet — but not always. For various reasons, vitamin supplementation is sometimes required. 

Although it is possible to overdose on vitamins, especially those fat-soluble, it is often rare. That is why following the recommended serving amount on supplement labeling is so important. Proper dosage matters. At Shop Hope, we understand this importance. 

If used as directed, vitamins can provide a nutrient boost to help maintain overall health and wellness. 



Vitamins | U.S. National Library of Medicine

Vitamin B6 | NIH

Vitamin A | NIH

Nutrient Recommendations | NIH