The main source of vitamin D (80-90%) is exposure to solar UVB radiation. The diet provides about 10-20% of the requirement.
What is the role of vitamin D?
The main function of the vitamin is to promote the reabsorption of calcium in the kidney, the intestinal absorption of phosphorus and calcium and the processes of bone mineralization.
Vitamin D also performs numerous functions unrelated to bone structure, thus influencing various physiological processes.
What is the daily requirement of Vitamin D?
The daily requirement of this vitamin varies according to sex and age and is higher in children in the first year of life, in pregnant women, during breastfeeding and in the elderly.
In our work we have the opportunity to read the blood tests of various women of childbearing age and one of the values that are often deficient or very deficient is that relating to Vitamin D.
Vitamin D status is assessed by measuring the levels of the hepatic metabolite 25- (OH) -D in the blood and expressing its concentration in nanograms per milliliter (ng / ml).
From the dosage of this metabolite you can have these conditions:
- Deficiency: Values below 20 ng / ml
- Insufficiency: Values between 20 and 30 ng / ml
- Normality: Values between 30 and 100 ng / ml
- Toxicity: Values above 100 ng / ml
What are the conditions that increase the demand for Vitamin D?
- Living in places where sunlight is lacking.
- Pregnancy and breastfeeding.
- Old age.
- Having dark skin.
- Spending a lot of time indoors or wearing very opaque clothing.
How Much Vitamin D Should I Take While Pregnant?
Pregnancy is a condition that exposes you to vitamin D deficiency and, according to the FIMP (Italian Federation of Doctors and Pediatricians), all pregnant women should take a supplement equal to 600 IU / day. In women with risk factors for vitamin D deficiency, dosages should be higher, equal to 1,000-2,000 IU / day.
How long ? From the very beginning of pregnancy, throughout the duration of pregnancy and breastfeeding.
Without this supplement, there is a risk that the baby will have brittle bones which can lead to rickets (a disease that affects bone development in babies).
Some women are more likely to need vitamin D than others. The risk of being Vitamin D deficient increases if:
- High skin pigmentation
- Reduced exposure to sunlight
- Previous child suffering from rickets
- Taking medications that interfere with the metabolism of vitamin D
- Increased risk of preclampsia
How long in the sun?
The amount of time you need to spend in the sun to make enough vitamin D is different for everyone and depends on your skin type, time of day and time of year.
It is not necessary to sunbathe in the literal sense and that is to take a tan.
15 minutes of sunshine a day, two or three times a week, should be enough, exposing only the arms and face.
What Foods Contain Vitamin D?
Foods rich in vitamin D include eggs, oily fish (such as salmon and sardines). Some breakfast cereals and yogurt are also enriched with vitamin D.
As always, keep in mind that some foods should be avoided in pregnancy. For example, the liver is rich in vitamin D, but you shouldn’t eat it during pregnancy.
It is difficult to get enough vitamin D from food alone, so the best thing to do is to try to eat a healthy and balanced diet as well as possible during pregnancy and while breastfeeding. You can also try exercising outdoors in the sun whenever possible and safely.
Does my baby need vitamin D?
Breastfed babies (breast milk contains insufficient amounts of vitamin D to prevent vitamin D deficiency) from birth to 1 year of age in the absence of risk factors are recommended to be given 400 IU / day of vitamin D. In the presence of risk factors for vitamin D deficiency, up to 1,000 IU / day of vitamin D can be administered.
There FIMP (Italian Federation of Pediatricians) recommends vitamin D prophylaxis in the first year of life even for bottle-fed babies. The vitamin D content of formula milk is about 400 IU / l, but an infant is able to take a liter of formulated milk per day only when it reaches a weight of about 5-6 kg, therefore a few months after the birth. Upon reaching this weight, bottle-fed infants often begin weaning with the concomitant reduction in the amount of formulated milk they consume.
In any case, the pediatrician is the primary reference to ask for information about the vitamin D supplement.
What effects on the newborn?
A systematic review of several recent studies published in the authoritative scientific journal Fertility and Sterility revealed that Vitamin D supplements during pregnancy could increase babies’ birth weight and length.
A team of scientists analyzed data on 2,299 newborns who participated in 13 studies. Meta-analysis found that mother’s vitamin D supplementation during pregnancy is associated with slight but significant increases in birth weight and length: 108 grams more weight and 0.3 cm more length. .
Women taking vitamin D had a significant increase in blood of 25 (OH) D.
Vitamin D exists in two precursors:
- D3: cholecalciferol, is synthesized in the skin thanks to sun exposure starting from 7-dehydrocholesterol, vitamin D3 is also introduced with food through animal fats
- D2: ergocalciferol: derives from ergosterol (again due to solar irradiation) which comes from food.
Both D3 and D2 are transformed in the liver and kidneys into 25 hydroxyvitamin D (25) D (OH) which is the inactive form, and calcitriol D (1.25 (OH) 2D) which is the biologically active form.
A vitamin D deficiency in adults is linked to osteopenia, osteoporosis, muscle and bone weakness, predisposition to cancer, autoimmune diseases, infectious diseases and cardiovascular diseases.
Vitamin D works by promoting intestinal absorption of calcium.
The researchers found no link between vitamin D and the incidence of preeclampsia, gestational diabetes, and preterm birth. The only link in evaluating pregnancies and newborns was found with the increase in weight and length of the newborn as you see from the table below published in the study:
Fetal growth is a complex process that depends on many factors, including genetic background, placental development, nutrition and physical activity.Therefore, vitamin D may play a lesser role in fetal growth than other factors.
According to the researchers it would be recommended that the pregnant woman take the daily dose of vitamin D of 600 IU, as many women around the world today would not receive the minimum recommended dose of vitamin D.
Faustino R. Pérez-López, Vinay Pasupuleti, Edward Mezones-Holguin, Vicente A. Benites-Zapata, Priyaleela Thota, Abhishek Deshpande, Adrian V. Hernandez, “Effect of vitamin D supplementation during pregnancy on maternal and neonatal outcomes: a systematic review and metaanalysis of randomized controlled trials “http://dx.doi.org/10.1016/j.fertnstert.2015.02.019