No vitamin is discussed as much as vitamin D. Much helps much is a mistaken assumption, because too much of the vitamin has serious effects on the organism. Therefore, some points must be observed when taking vitamin D in order to avoid undesirable side effects. The good news is that side effects of vitamin D as a result of overdose only occur when supplements are used improperly.
When do side effects occur?
Side effects of taking vitamin D only occur if you take significantly too much of it. Such an overdose is hardly possible with normal food or by exposing the skin to the sun. Only when light-skinned people with scanty clothing regularly spend hours in the blazing sun have increased kidney stones been observed as a side effect of elevated vitamin levels in the blood.
Information on the daily intake of vitamin D varies considerably. Based on the literature, the German Nutrition Society (DGE) assumes that only a permanently excessive intake of more than 100 micrograms per day leads to side effects. For children up to the age of ten, the limit is 50 micrograms. This is in line with the opinion of the European Food Safety Authority (EFSA). It recommends a daily intake of 15 micrograms from the first year of life and 10 micrograms from the seventh to the eleventh month of life.
Vitamin D: Side effects of taking – The most important at a glance!
- When taking vitamin D, side effects occur only with overdose.
- Hypervitaminosis D is not possible with normal food and sun exposure, only through improper use in supplements.
- It is important in a substitution to have an adequate supply of calcium and magnesium, otherwise there will be disturbances in bone metabolism.
- Also important is vitamin K, which also regulates calcium balance.
- Side effects range from nausea and vomiting to altered bowel movements and drowsiness.
- In extreme cases, depression, delusions and even coma can occur.
Why do side effects occur with vitamin D overdose?
In the case of overdosed preparations, the body stores the excess in muscle and fatty tissue. Vitamin D is a fat-soluble vitamin which, unlike water-soluble vitamins such as vitamin C or the B vitamins, cannot be excreted via the kidneys if there is too much of it. This is referred to as hypervitaminosis, in contrast to an undersupply (hypovitaminosis), which is also associated with numerous side effects.
How important are cofactors in vitamin D uptake?
Side effects occur mainly when crucial cofactors of the calcium balance are missing. These include in particular the minerals calcium and magnesium as well as vitamin K.
The role of vitamin K
Along with vitamin D, vitamin K is important for calcium balance. If it is lacking in substitution, too little of the mineral is stored in the bone substance. This leads to increased calcium deposits in the vessels and arteriosclerosis occurs.
Magnesium deficiency as a side effect of vitamin D poisoning
A typical side effect of an overdose is magnesium deficiency. Magnesium is needed for conversion to the hormonally active form. If too much of it is consumed, symptoms such as
- Muscle cramps
- tiredness and fatigue
- poor performance
Therefore, it is always important to ensure an adequate supply of magnesium.
Hypervitaminosis and calcium balance
The sunshine vitamin regulates the build-up and breakdown of bone substance and thus the release of calcium from skeletal stores. High doses of vitamin D therefore lead to a massive increase in calcium levels in the blood, a hypercalcemia. It manifests itself with
- Loss of appetite
- Nausea and vomiting
- tiredness and fatigue
- Impaired concentration
- fluid loss due to increased urge to urinate
- thereby great thirst
- initially diarrhea, later constipation
- bone pain
- muscle weakness
- stomach ulcers
- inflammations of the pancreas
- Inflammation of the conjunctiva and/or cornea (keratitis) of the eye.
Serious long-term effects are shown by the loss of fluids when calcium levels are high. The corresponding mineral salts concentrate in the renal tubules due to increased excretion to such an extent that they precipitate. The consequences are renal calcification (nephrocalcinosis) and kidney stones (calcium stones).
Calcium deposits also occur in other blood vessels and in the heart and lungs. In extreme cases, the increasing dehydration leads to
- comatose states.
Muscle weakness in elderly patients should not be underestimated. It leads to an increased tendency to fall – fatal, of all things, when one is trying to alleviate the consequences of osteoporosis.
Preventing vitamin D side effects in a targeted manner
With a healthy and balanced diet, there is no danger of an oversupply of vitamin D. The same applies to vitamin D, which the body produces through the influence of UV radiation from sunlight. The body is able to adapt the synthesis of vitamin D to the respective need. At an optimal vitamin D supply, the organism automatically “shuts down” photosynthesis.
An additional intake of vitamin D in the form of supplements is unnecessary in a healthy lifestyle. Dietary supplements contain vitamin D in high doses, which, if taken improperly, lead to an excess and the listed vitamin D side effects. Exceptions are children up to the age of one and people who rarely spend time outdoors due to their age. In addition, certain diseases require additional administration of vitamin D.
If you include enough vitamin D-containing foods such as cod liver oil or tuna in your diet and get plenty of exercise in the fresh air, you can do without additional supplements and their side effects.