Some studies have shown that vitamin D can increase the receptivity of the endometrium and therefore the possibility of pregnancy. What the expert says.
When trying to become pregnant, dietary habits and lifestyles are essential to increase the chances of conception and the birth of a healthy baby.
A rather frequent deficiency in the general population is that which concerns vitamin D, a steroid hormone produced mainly in the skin thanks to exposure to sunlight, with less than 10% coming from food sources. Recently its receptor (VDR) has been found in the ovaries, uterus, placenta and testis, as well as in the hypothalamus and pituitary gland, suggesting its role in reproductive physiology.
Functions of vitamin D
The main and best known function of vitamin D is to promote the bone mineralization process, increasing the intestinal absorption of phosphorus and calcium, and decreasing the excretion of calcium in the urine. In addition to the actions on bone tissue, vitamin D performs numerous others commonly grouped under the term of extra-skeletal actions.
Among these, its contribution to the proper functioning of the body’s defense system(immune system)is of particular importance. In particular, vitamin D is important for the activation of the first line of defense against some pathogenic microorganisms since it increases the ability of the cells of the immune system, responsible for this function, to eliminate microorganisms. Furthermore, it has the ability to modulate the inflammatory response by controlling the degree of activation of many cells of the immune system and the production of factors involved in inflammation.
Vitamin D and fertility
A growing number of evidence also suggests that deficient levels are associated with typical manifestations of polycystic ovary syndrome(PCOS) including anovulation, hyperandrogenism and insulin resistance-and that its integration, aimed at restoring optimal circulating values, is able to improve menstrual cycles, hyperandrogenism and various metabolic aspects of this syndrome.
Some studies have highlighted a positive correlation between serum levels of vitamin D and AMH (or Anti-Mullerian hormone, the value of which, according to many scholars, is an indicator of female fertility because it allows to evaluate the number of residual primordial follicles): a deficiency of previously it would appear to be associated with a lower ovarian reserve, although this aspect needs further investigation. Other studies have shown how vitamin D – through its binding to its endometrial receptor and the modulation of the immune system, a crucial aspect during embryonic implantation – can increase the receptivity of the endometrium and therefore the possibility of pregnancy.
Finally, various researches underline the importance of this vitamin in pregnancy as it is involved in placental development and fetal programming.
However, “It must be emphasized that the studies conducted so far on vitamin D and fertility come to heterogeneous and sometimes conflicting results . Although vitamin D deficiency appears to be detrimental to fertility, it is unclear whether higher levels confer additional benefits once sufficiency is reached,” explains Dr. Domenico Carone, Specialist in Gynecology and Obstetrics with address in Physiopathology of Human Reproduction and Medical Coordinator of the Eugin Taranto Clinic.
Sources of vitamin D
About 90% of the vitamin D present in the body is obtained from the action of the sun’s rays on the cholesterol in the skin, which is transformed into vitamin D. The rest, about 10% comes from food . They are rich in this substance:
- Fatty fish, such as salmon, sardines, herring and mackerel (4.2-17 micrograms per 100 grams)
- Liver
- Egg yolks (4.5 micrograms per 100g)
- Chocolate, has appreciable vitamin D content in 100 grams, even if it is not a quantity to be consumed frequently due to the high caloric intake
- Fruit and vegetables, in minimal quantities and in the least bioavailable variant (vitamin D2)
- Mushrooms contain vitamin D2 of vegetable origin.
Ideal values and vitamin D supplementation
In Italy, from early spring to late summer, a healthy person with no particular risk factors should be able to obtain sufficient amounts of vitamin D from sunlight.However, the amount of vitamin D produced depends on many factors, including time of day, season, latitude and skin color. Depending on where you live or your lifestyle, your vitamin D production may decrease or be completely absent during the winter months.
But what are the ideal values?In a note from AIFA (Italian Medicines Agency, 2019) with which the indications for the “Prevention and treatment of vitamin D deficiency” in the adult population were updated, the desirable values of 25(OH)D are indicated as between 20 and 40 ng/mL. Indicative values of vitamin D “deficiency” are instead identified for 25(OH)D values lower than 20 ng/mL.
However, “As important as it is to identify these deficiencies as quickly as possible, do-it-yourself is always not recommended, especially as regards the intake of any supplements,” suggests Dr. Charone. “If in some cases they may be only useless and superfluous, in others they could be harmful, for example by interfering with any drugs taken,” concludes the expert.
For this reason it is advisable to always discuss with the reference specialist, who will be able to guide you towards the most rational choice.