What vitamin D value is optimal?

Vitamin D is a vital vitamin. But what blood value is considered optimal? Read the answer here.

Vitamin D has many functions in the body. However, its role in bone metabolism is particularly important. vitamin D promotes the absorption of calcium and phosphate and is therefore essential for bone health. Therefore, a vitamin D deficiency can cause bone deformities. But when should you start taking nutritional supplements and what value of vitamin D is considered optimal?

How is the vitamin D value determined?

The vitamin D value is determined by blood values. According to the Robert Koch Institute (RKI) 25-Hydroxyvitamin-D, abbreviated as 25(OH)D. “Various reference values ​​can be used to evaluate serum 25(OH)D values,” writes the RKI. A commonly used classification is that of the US Institute of Medicine (IOM). There are classifications that indicate the serum value in nanomoles per liter (nmol/l), nanograms per milliliter (ng/ml) or micrograms per liter.

According to the RKI, the serum value fluctuates greatly. Especially in winter, in this country the body normally cannot produce enough vitamin D. According to the institute, this does not mean that deficiency symptoms also occur.

What vitamin D value is optimal?

Depending on the source, different values ​​are given for the optimal supply of vitamin D. The RKI, for example, gives different values ​​to those of the National Institute of Health in the USA.

If you request it, Kai-J will inform us. Lüthgens, a specialist in laboratory medicine from Stuttgart, says: “In almost no other area is there such different information and recommendations on the normal value as for 25-OH vitamin D.”

According to the RKI, a vitamin D value between 30 and 50 nanograms per milliliter is considered optimal. Here is the overview:

25(OH)D in nmol/l 25 (OH)D in ng/ml possible effects
<30 <12

vitamin D deficiency

Risk of:

  • Bone disease in children and adolescents (rickets)
  • Disorders of bone formation (osteomalacia)
  • Porous bones (osteoporosis)
30 to <50 12 to <20 Suboptimal supply/deficiency of vitamin D
50 to <75 20 to <30 Lower normal range; Proper care when it comes to bone health.
75 to <125 30 to <50

optimal vitamin D value

≥125 ≥50

Possible oversupply, with possible health consequences

Risk of:

  • Cardiac arrhythmia
  • kidney stones
  • Oversupply with calcium

Kai J. Lüthgens from the Enders laboratory speaks of a vitamin D deficiency at levels below 20 nanograms per milliliter, while the RKI continues to speak of a “suboptimal intake.” Anything less than 10 nanograms per milliliter is considered a serious vitamin D deficiency and can have serious consequences.

It is also important to know: while the RKI speaks of a possible excess supply at values ​​​​above 50 nanograms per milliliter, the Enders laboratory only assumes an excess supply from 70 nanograms per milliliter. It becomes toxic when vitamin D levels exceed 150 nanograms per milliliter. According to the German Nutrition Society, adults should take 800 IU (international units) of vitamin D if they do not spend enough time in the sun. According to the American Endocrine Society, people at risk of vitamin D deficiency, due to illness or lack of sun exposure, should even take higher supplements over a given period of time.

How do low vitamin D levels occur?

Vitamin D is the only vitamin that the body can produce on its own. But for this it needs enough sunlight per day. The Robert Koch Institute (RKI) writes that daily vitamin D needs can only be met by spending time outdoors. For the body to produce enough, it needs UV-B radiation at a certain wavelength, between 290 and 315 nanometers. This intensity depends on the season below the 35th parallel. According to the Swiss Federal Office of Public Health, in Germany fair skin people sometimes have to spend up to 2.5 hours outdoors in winter so that the body can produce enough vitamin D. Darker skin types can hardly or not at all reach the necessary values ​​in this country in winter. According to the RKI, low levels of vitamin D in the blood can occur, especially in the dark season.

Although the body in this country cannot produce much vitamin D in winter, according to the RKI, it can draw on reserves of fat and muscle tissue, provided it has been exposed to the sun for sufficient time beforehand.

How long does it take to correct a vitamin D deficiency?

If low levels of vitamin D have been detected in the blood, the deficiency must be corrected. The duration of this depends on two factors: body weight and serum levels in the blood. The lower the vitamin D value and the higher the body weight, the longer it will take to correct the deficiency. 10,000 international units (IU) increases vitamin D levels by approximately 1 nanogram per milliliter.

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