How to Recognise an Excess of Vitamin D

An accumulation of fat-soluble vitamins like vitamin D can be harmful. It is indeed possible to consume too much vitamin D, primarily through excessive supplement use.  

Read more about which form of vitamin D is best absorbed.  

Too Much Vitamin D from the Sun 

It is almost impossible to get too much vitamin D from sun exposure. Our body is uniquely designed and constantly seeks balance. When you are in the sun, your skin regulates the production of vitamin D. After a certain amount, this production stops.³ Here's how it works: 

1. When UVB radiation reaches the skin, a cholesterol derivative called 7-dehydrocholesterol is converted into previtamin D3. 

2. Previtamin D3 is then converted into vitamin D3 (cholecalciferol) by the warmth of the skin. 

3. After a certain amount of UVB exposure, the 7-dehydrocholesterol in the skin becomes saturated, reducing the production of previtamin D3. This prevents the creation of too much vitamin D3. 

Therefore, you don't need to worry about getting too much vitamin D from the sun. However, it is wise to avoid prolonged sun exposure without the protection of clothing or sunscreen. 

Too Much Vitamin D from Food 

Vitamin D in food is mainly found in fatty fish, liver, and sometimes in fortified foods like milk and cereals. It's good to know that food rarely contributes to an excess of vitamin D because food contains only small amounts of vitamin D. For instance, anchovies contain 11 mcg per 100 grams, and salmon has 4.6 mcg per 100 grams.  

For adults, the recommended daily amount of vitamin D is between 10-20 mcg, depending on age, gender, and specific health needs. The European Food Safety Authority (EFSA) has set the tolerable upper intake level for vitamin D at 100 mcg per day for adults. This means that an intake of up to 100 mcg of vitamin D per day is considered safe.  

To consume 100 mcg of vitamin D, you would need to eat about 2.1 kilos of salmon. Even with a diet rich in these products, it's very unlikely to reach the toxic threshold. 

Too Much Vitamin D from Supplements 

The most common cause of too much vitamin D is the excessive use of (high-dose) supplements. While vitamin D is beneficial for the bones and the immune system, an overdose can lead to a dangerous increase in blood calcium levels. This is because vitamin D aids in the absorption of calcium from food. An excessive calcium level can cause symptoms such as nausea, fatigue, and in severe cases, kidney problems. 

It's important to emphasise that an excess of vitamin D is rare. It usually only occurs with very high doses of supplements over a long period. Taking a maintenance dose daily, such as 10 mcg, is not an issue. Supplements can be a useful addition, especially during the winter months or for people who are not often exposed to sunlight. 

Side Effects of Too Much Vitamin D 

Although less common than a deficiency, an excess of vitamin D can be harmful. Symptoms of too much vitamin D include: 

• Nausea and vomiting
• Loss of appetite
• Constipation
• Fatigue
• Excessive thirst and frequent urination
• Confusion and disorientation 

 Long-term overdosing can lead to more serious problems such as kidney stones and kidney damage. 

 Read more about vitamin D deficiency and how to recognise the symptoms.   

Risk Factors for Too Much Vitamin D 

Certain groups of people are at higher risk for too much vitamin D. These include: 

• People taking high doses of vitamin D supplements without a real need. 
• People whose bodies produce abnormally high amounts of vitamin D. 

The Role of Vitamin K2 

Vitamin K2 plays an important role in regulating calcium in the body. It ensures that calcium goes to the right places in the body. Vitamin K is therefore important for bone composition and also contributes to maintaining strong bones.  

Vitamin D then contributes to the normal absorption of calcium and increases calcium uptake in the bones. The balance between vitamin D and K2 is therefore also important.   

Read more about vitamin D and K.  

How to Prevent Too Much Vitamin D 

Prevention is, of course, the most important. Here are some tips to prevent consuming too much vitamin D: 

• Check the recommended dosage on the packaging.
• Follow the advice of an expert or dietitian on supplement use.
• Occasionally have your blood levels checked if you use vitamin D supplements for a long time.
• Use supplements that contain a combination of vitamin D and K2 for better balance. 

What to Do if You Have Too Much Vitamin D 

If you think you've taken too much vitamin D, contact a doctor immediately. The most important and obvious step is to stop taking vitamin D supplements right away. Additionally, you can also: 

• Temporarily reduce the intake of calcium-rich foods.
• Drink plenty of water to reduce the risk of kidney stones. 

The Importance of Balance Between Vitamins 

A good balance between different vitamins and minerals is an essential part. Besides vitamin D and K2, it's important to also pay attention to the intake of other nutrients, such as magnesium and omega 3 fatty acids. These can help regulate vitamin D levels. 

Good to Know 

An excess of vitamin D mainly occurs due to excessive use of supplements. Are you often in the sun? Then you don't need to worry about getting too much vitamin D. Your body regulates this very well. However, pay attention to the dosage of your supplements and seek advice from an expert. Don't forget to keep an eye on the balance between vitamin D and K2. Our Health Coaches are ready to provide you with free personal advice. 

Sources 

1. Nair, R., & Maseeh, A. (2012). Vitamin D: The “sunshine” vitamin. Journal of pharmacology and pharmacotherapeutics, 3(2), 118-126.
2. Stevens, S. L. (2021). Fat-soluble vitamins. Nursing Clinics, 56(1), 33-45.
3. Knuschke, P. (2021). Sun exposure and vitamin D. Challenges in Sun Protection, 55, 296-315.