Vitamin D: needs, limits and research

This is information, not a recommendation. We do not advise you to take anything. Under 18 or with an eating disorder, including a past one: this text is not aimed at you, and you will find places to turn to under When to get medical advice. During pregnancy or breastfeeding, with kidney disease or on medication, ask a doctor first.

What expert bodies say

Value	Amount	What it means
DGE estimate	20 µg a day	Applies only if the body makes none itself^[1]
Usual diet	2 to 4 µg a day	In young people and adults^[1]
BfR proposed maximum	20 µg per daily portion	For food supplements^[3]
EFSA upper limit	100 µg a day	From all sources, for adults. This is not an intake recommendation^[4]^[2]

1 µg equals 40 international units, so 20 µg is 800 IU.^[1] According to the DGE, frequent sun can achieve the desired supply without a product.^[1]

According to the BfR, about 44% of adults in Germany have desirable blood levels of 50 nmol/l or more, about 41% are in the suboptimal range of 30 to 50 nmol/l, and about 15% are below 30 nmol/l, with a risk of deficiency.^[2] As risk groups, the BfR mainly names people who hardly get outdoors, for example in old age or when in need of care.^[2]

What may be said in the EU

These are examples of authorised claims, and only for foods that are at least a source of vitamin D as defined in the regulation:^[5]

“Vitamin D contributes to the maintenance of normal bones”
“Vitamin D contributes to the maintenance of normal muscle function”
“Vitamin D contributes to the normal function of the immune system”
“Vitamin D contributes to normal blood calcium levels”

There is no authorised claim on losing weight or building muscle.^[6]

Vitamin D and losing weight

People with overweight and obesity have lower blood levels on average. In an analysis of 22,214 measurements, levels with obesity were about 19.8 nmol/l below those at normal weight.^[7] Losing weight often brings them up a little: in studies the difference averaged about 3 nmol/l.^[8]

Products did not lead to more weight loss. An analysis of 11 trials with 947 people found no difference in weight and small differences in BMI and waist size. The trials were built very differently.^[9]

Strength and bones

In 436 athletes across 11 trials there was no statistically reliable effect on maximum strength or jumping power.^[10]
In 1,054 older adults, 2,000 IU a day for 2 years did not change strength or walking speed.^[11]
In 25,871 men from 50 and women from 55, not selected for deficiency, 2,000 IU a day did not reduce fractures.^[12]

A 2024 US guideline foresees amounts above the reference intake without a prior blood test only for certain groups, such as people from 75 or during pregnancy. It does not foresee this for other adults.^[13]^[14] The paper is not undisputed, especially on doses and blood tests.^[14]

Safety and when to ask

Too much vitamin D over time can raise blood calcium. Possible signs are tiredness, muscle weakness and nausea, and in the long run kidney stones and kidney damage can follow.^[2]

The BfR advises against high single doses, because studies saw more falls and fractures with them.^[2]
Products add up, including fortified foods.^[15]
Medication: Interactions exist with, among others, the weight-loss drug orlistat, statins, steroids and thiazide diuretics.^[16]
With kidney disease, pregnancy or regular medication, clarify need and amount with a doctor.

The app does not replace medical advice.