Vitamin D is a group of fat-soluble vitamins with hormone-like functions. Although Turkey is in a geographical location with plenty of sunlight, vitamin D deficiency in pregnant women, infants, children and adults is becoming more common day by day. Vitamin D synthesis is almost nonexistent, especially in the winter months, as we make little use of the sun.
Therefore, vitamin D deficiency will be an indicator of disease, and many health problems arise with its deficiency. I hope that this article, which we prepared with dietician Selvi Pamukçu, and which can be read with interest by our esteemed readers, will attract attention.
Synthesis of Vitamin D in the Body
Vitamin D precursors taken from plant and animal origin are synthesized in the skin and in the body. Vitamin D occurs in two ways.
With the help of sunlight on the skin;
Adequate vitamin D intake, 20 minutes a day exposure to light on the arms, legs and face may be sufficient. Vitamin D
80% of all vitamin D production takes place in the skin
20% of the rest is ergocalciferol (vitamin D2) from plant sources and cholecalciferol (vitamin D3) from animal sources
2. With dietary intake of vitamin D2 and vitamin D3;
Cholecalciferol (D3) from animal foods and ergocalciferol (D2) from plant foods are absorbed from the small intestines. Absorbed Vitamin D is metabolized in the liver. Excess Vitamin D is stored in liver, fat and muscle tissues. Some of the vitamin D is converted in the liver to 25-hydroxycholecalciferol [25(OH)D3] or 25-hydroxyergocalciferol [25(OH)D2]. Although a significant part of the unstored Vitamin D is converted to 25(OH)D3 and passes into the blood, a small part of it is processed in the liver, transported to the intestine via bile and reabsorbed from the small intestine (enterohepatic circulation). 25(OH)D3 or 25(OH)D2 in the plasma comes to kidney cells and transforms into 1.25(OH)2D3 or 1.25(OH)2D2 inside the cell with the effect of hydroxylase enzyme, forming active Vitamin D Metabolite.
The role of vitamin D in the body
Vitamin D directly affects bone mineral metabolism by facilitating calcium and phosphorus absorption from the intestine and stimulating phosphorus reabsorption from the kidneys.
Skeletal system and vitamin D ; Diseases that occur with symptoms in the skeletal system with its deficiency are rickets and osteomalacia. Rickets is very common especially in infants and early ages. In rickets, the bones become soft and bend easily. There are X or O shaped deformities in the legs. Osteomalacia is common in adults and the bones are softer. Calcium absorption and bone mineral density are low in the body. The risk increases in people who give birth frequently, have an inadequate and unbalanced diet, and cannot benefit from the sun.
Obesity and vitamin D; Vitamin D deficiency can increase fat deposition under the skin. Since fat tissue increases in obesity, vitamin D is stored more in this tissue.
The population of vitamin D deficiency due to metabolic syndrome, which is defined as a cardiometabolic risk factor that develops in common genetic and environmental environments and is characterized by waist circumference, high blood pressure, disorder in blood lipids, and high blood sugar, is seen as 30-60% in the world. .
Vitamin D intake reduces BMI (Body Mass Index) and can balance blood pressure by regulating blood pressure together. In addition, Vitamin D prevents the development of some cancers (breast, prostate, colon, rectum cancer), autoimmune diseases, heart diseases.
We can list the groups at risk of vitamin D deficiency as follows
Pregnant and lactating women
Infants and children <5 years old
With people <65 years old
Those who benefit less from the sun or work indoors
Those with dark skin structure (such as African and South Asian origin)
Also, when we look at the causes of deficiency, those who have insufficient vitamin D intake with diet, obesity (obesity) ), fat absorption disorders (cystic fibrosis, celiac, whipple, crohn’s diseases), those who use drugs that increase catabolism (glucocorticoids), liver failure, nephrotic syndrome, chronic kidney failure, genetic diseases (vitamin D-dependent rickets type 1-2-3). ), symptoms of deficiency of this vitamin are very common in people with hyperthyroidism and in infants using breast milk.
Serum vitamin D levels
Serum 25-Hydroxy vitamin D (25-OH D) measurement is usually performed to evaluate the vitamin D level of the individual.
25(OH)D level; Vitamin D deficiency if it is less than 20 ng/ml D,
vitamin D deficiency if it is between 21 and 29 ng/ml,
normal vitamin D level if it is between 30 and 80 ng/ml,
80 ng/ml If it is higher than 1 ml, it is determined as high vitamin D level
, and if it is higher than 150 ng/ml, it is determined as vitamin D intoxication.
Vitamin D sources
It can be taken in the form of ergocalciferol (vitamin D2) found in plants and cholecalciferol (vitamin D3) found in animal tissues with diets high in this vitamin. As we can see in the table below, the main source of vitamin D is sunlight, and in foods, it is mostly found in deep-oil water fish (salmon, sardines, mackerel, tuna), cod liver and egg yolk.
| Vitamin D
Natural Sources |
|
| Cod liver oil | ∼400–1,000 IU/teaspoon vitamin D3 |
| Salmon | ∼600–1,000 IU/100 g vitamin D3 |
| Sardines | ∼300 IU/100 g vitamin D3 |
| Mackerel | ∼250 IU/100 g vitamin D3 |
| Tuna | 236 IU/100 g vitamin D3 |
| Shiitake mushrooms | ∼100 IU/100 g vitamin D2 |
| Egg yolk | ∼20 IU/egg yolk vitamin D3 /D2 |
Vitamin D deficiency prevention and treatment approach
To prevent a deficiency of this important vitamin, the Endocrine Society uses its own practice. In the a guidelines, 400-1000 IU (safe up to 2000 IU) daily for infants in the first year, 600-1000 IU (safe up to 4000 IU) daily for children and adolescents aged 1-18 years, and adults over 18 years of age. recommends a daily vitamin supplement of 1500-2000 IU (safe up to 10,000 IU).
Inadequacy of this vitamin is common in our country and in the world. Considering that this situation will be related to limited sunlight exposure and dietary factors, we think that adequate vitamin D intake from appropriate dietary sources should be provided to people and supplementation would be appropriate to meet the body’s needs.
1 egg every day, 2 glasses of full-fat milk or its products, within the framework of adequate and balanced nutrition, with direct contact of the head, face, hands, arms, feet and legs with the sun’s rays for 30 minutes every day, 1- Adult people can meet their vitamin D needs by consuming 2 fatty fish. Those who cannot meet these conditions should be given additional vitamin D under the control of a doctor.
References;
Fatma Uçar1, Mine Yavuz Taşlıpınar1, Ayşe Özden Soydaş1, Nurgül Özcan. 25-OH Vitamin D Levels in Patients Admitted to Ankara Etlik Specialization Training and Research Hospital. Eur J Basic Med Sci 2012;2(1):12-15
Belkız Öngen Ceyda Kabaroglu Zuhal Parıldar. Biochemical and Laboratory Evaluation of Vitamin D. Turkish Journal of Clinical Biochemistry 2008; 6(1): 23-31
Laird E, McNulty H, Ward M et al. Vitamin D deficiency is associated with inflammation in older Irish adults. J Clin Endocrinol Metab. February 2014.
