What is the effect of vitamin D on our daily functioning?
Vitamin D is a very important factor in maintaining proper bone metabolism – it determines active absorption from the gastrointestinal tract of calcium, phosphorus and magnesium supplied in the diet. Without vitamin D, only a small percentage of calcium is passively absorbed from the intestines, which in the long run leads to hypocalcaemia and activation of compensatory mechanisms to maintain normal calcium concentrations, i.e., secondary hyperparathyroidism and release of calcium from the bones. Hyperparathyroidism also results in increased urinary excretion of phosphorus and impaired absorption of phosphorus from the gastrointestinal tract. Hypocalcaemia and hypophosphatemia lead to impaired bone mineralization and the development of rickets, which can manifest in adults as muscle weakness, bone pain, deformities, and fractures.
In children, the symptoms of rickets vary with age:
- at 1 year of age, widening of the cranial sutures and fontanels, flattening of the back surface of the skull, softening of the occipital bones, widening of the wrists, deformation of the ribs, delayed eruption of teeth, loss of tooth enamel, weakening of muscle strength and muscle tone (difficulty in unsupported walking, flaccidity of the abdominal integuments)
- after the age of 1 year, due to the stress caused by upright positions and walking, the main symptoms of rickets are in the lower limbs, which become bandy-legged or club-footed. Growth limitation and fractures may occur.
Maintaining adequate vitamin D levels (with a calcium-rich diet) benefits the skeletal system. Another advantages of Vitamin D are also noteworthy:
- reducing the risk of cardiovascular disease,
- reducing the risk of cancer,
- reducing the risk of diabetes,
- reducing the risk of infections and autoimmune diseases.
The main source of vitamin D in humans is cutaneous synthesis under the influence of ultraviolet radiation. Only up to 20% of vitamin D can be provided in the diet (primarily from high-fat marine fish and egg yolks), which is insufficient to prevent deficiency. Due to the fact that sunlight in moderate latitudes (and therefore also in Poland) provides an adequate amount of ultraviolet radiation only in the summer months (provided that sunscreens with UV filters are not used), it is recommended to supplement with vitamin D in the autumn and winter months. Optimal vitamin D concentrations are considered to be serum concentrations in the range of 30-50 ng/ml.
There are many vitamin D preparations available on the market- in the form of drops, capsules, also to be taken every few weeks. The minimum prophylactic dose in an adult is 800-1000 IU per day for use from October through April. The highest allowable prophylactic dose is 4000 IU/d). In people over the age of 65, supplementation should be done year-round due to decreased dermal synthesis. Pregnant women should supplement with vit. D in a dose of 2000 IU/d (this dose of vit. D is contained in vitamin preparations appropriate for pregnancy). Higher prophylactic doses are used in obese people and those over 75 years of age (here the dose is increased to 4000 IU/d).
Therapeutic doses (used after a deficiency is established) are higher and are in an adult 7- 10,000 IU/d for 1-3 months or 50,000 IU in a monthly dose. Control of deficiency compensation (serum 25(OH)D determination) makes sense after 6-8 weeks of treatment.
Since the use of too high a dose carries a risk of overdose, it is worth paying attention to the composition of the nutrients and vitamin preparations used, and in case of doubt, seek advice from your doctor.