Vitamin D Overdose: How to Recognize and Prevent It

Inge has been suffering from constant fatigue for more than a week. She feels weak, exhausted and has noticeably less appetite. What sounds like the symptoms of any disease has a very specific reason: Inge suffers from a vitamin D overdose.

But how did it come about and how can you avoid such an overdose of the vitamin?

In addition to fatigue and weakness, too much vitamin D can cause a wide range of consequences. This often makes a diagnosis difficult.

Therefore, it is all the more important to prevent a vitamin D excess at all. In most cases, you are responsible for it yourself. But more on that later.

Let’s start at the beginning: How much vitamin D do we need at all and when do we start talking about an overdose?

When is it too much vitamin D?

Anyone who has ever taken a look at vitamin D supplements in the supermarket or pharmacy has certainly come across the unit of measurement “IU”. How much of the vitamin is contained in a product is usually given in international units (IU). Such a unit corresponds to 0.025 μg (micrograms).

The German Nutrition Society (DGE) recommends about 20 μg of vitamin D as an appropriate daily intake for children and adults. Converted that is about 800 IU.

It should be noted that this intake is only recommended in the absence of endogenous synthesis, i.e. if you produce no or only a little vitamin D due to a lack of sun exposure.

In addition, vitamin D is not the same as vitamin D. The values of the DGE refer primarily to cholecalciferol or vitamin D3 – The “activated form” of vitamin D, calcitriol, is even more effective. If you take calcitriol directly, therefore also lower amounts apply to the harmless daily intake.

To achieve a harmful overdose with vitamin D3, it takes a much larger amount. According to science, the maximum daily intake value for vitamin D3 (cholecalciferol) is set at about 100 μg, i.e. 4000 IU .

But what exactly does “harmless” mean in this context?

Let’s look at how an overdose of vitamin D affects our body.

The symptoms of a vitamin D overdose

Too much vitamin D is mainly problematic because the vitamin promotes the absorption of calcium, magnesium and phosphates. An overdose therefore automatically increases the calcium level in the blood, which in turn leads to problems for bones and internal organs.

The symptoms are far-reaching:

• anorexia
• Tiredness, exhaustion and muscle weakness
• Psychological irritability and nervousness
• Headache
• Dehydration and constant feeling of thirst
• Constipation
• Vomiting and diarrhea
• Kidney stones and kidney damage

Since we often store vitamin D in the body for a long time before it is used by the metabolism, the symptoms sometimes do not appear until several months after an excessively high intake. This can make a diagnosis difficult.

For this reason, if you suspect an overdose, you should definitely consult your doctor, who can give you certainty with a blood test.

How is the treatment carried out?

As you can see, a vitamin D overdose can lead to serious damage to organs and therefore should not be underestimated.

Once the overdose is detected, however, it can be treated relatively effectively. This usually happens through a low-calcium diet and the administration of special steroid hormones. Due to this therapy, the symptoms usually subside completely within a month.

As always, however, the best countermeasure is to prevent an overdose from occurring in the first place. To do this, you must first know the reasons for overdoses.

What are the causes of an overdose of vitamin D?

Although vitamin D is also found in foods in lower doses, we cover the majority of our needs through the sun. The process in which the vitamin in our body is produced from sunlight is remarkable: light is absorbed by the skin and converted into usable vitamin D via several intermediate stages. This even works so well that excess vitamin D is excreted via the metabolism.

Your body regulates the absorption of vitamin D completely automatically, so to speak. Absorbing too much vitamin D only through sunlight is therefore simply not possible. Rather, the reasons for a vitamin D overdose lie in incorrectly used dietary supplements.

But you should not only be careful with supplements: Even the too rich consumption of foods that have been enriched with vitamin D can lead to a harmful vitamin D level.

With proper handling of these products, however, an overdose can be avoided well.

How to Avoid Too Much Vitamin D

Proper handling of dietary supplements primarily means knowing the instructions for consumption and observing them accordingly. So always remember to read the package or package leaflet before you start taking it.

Also, keep in mind that there are different forms of oral vitamin D and the recommended dose varies depending on the form. As a reminder:

• Most supplements contain vitamin D3, also called cholecalciferol .
• Recommended daily dose: ~ 20 μg or 800 IU
• Upper limit for the still safe daily intake: ~100 μg or 4000 IU
• If a supplement contains calcitriol, other guideline values apply

There are also studies that suggest that the negative effects of too much vitamin D have to do with a concomitant deficiency of vitamin K. In an animal experiment, the results of which were published in 2016 in the Turkish Journal of Medical Sciences, it has already been confirmed that the additional intake of vitamin K with vitamin D seems to reduce the effects of an overdose. However, this has not yet been researched in humans.

Especially when it comes to interactions between different vitamins and nutrients, science still faces a number of questions. In addition to the responsible use of supplements, it is therefore still important to listen to your own body. If there are signs of an overdose, your doctor can help you in a targeted manner.