Vitamin D

VITAMIN D is an essential fat-soluble Vitamin and one of the important many Vitamins our body needs to stay healthy. It plays a crucial role in maintaining the balance of calcium in the bones and thereby building and maintaining bones.

People with Vitamin D status of >30ng/ml are called Vitamin D sufficient. Vitamin D is calculated as circulating level of 25(OH)D in blood.

ROLE OF VITAMIN-D

Vitamin D plays a crucial role in numerous functions within our body. Some important functions and roles of Vitamin D include:

Promoting calcium absorption: Vitamin D helps the body absorb calcium from the gut, ensuring adequate levels of calcium and phosphate in the blood, which are essential for normal bone mineralization.
Supporting bone growth and remodeling: Vitamin D is necessary for proper bone growth and remodeling, as it helps the body utilize dietary calcium effectively. It contributes to the development of strong bones, especially during periods of growth.
Protecting against osteoporosis: Vitamin D, along with calcium, helps protect older adults from osteoporosis, a condition characterized by reduced bone density and increased fracture risk.
Preventing hypercalcaemic tetany: Vitamin D aids in preventing hypercalcaemic tetany, a condition characterized by involuntary contraction of muscles, leading to cramps and spasms caused by elevated calcium levels.
Modulating various systems: Vitamin D has implications on the nervous, musculoskeletal, and immune systems. It is involved in processes such as cell growth, neuromuscular function, immune function, and glucose metabolism.

SOURCES OF VITAMIN D:

Vitamin D is primarily synthesized by the skin when exposed to sunlight. About 50-90% of Vitamin D is absorbed through the skin via sunlight while the rest comes from the diet.
To prevent Vitamin D deficiency, 20 minutes of sunshine daily is recommended with over 40% of the skin exposed. This can vary depending on factors such as the time of year, geographical location, skin type, and individual circumstances.
Dietary sources of Vitamin D are fatty fish, fish liver oil, egg yolks, cheese, dairy products, and cereals fortified with Vitamin D.
After synthesis in the skin or dietary intake, Vitamin D undergoes conversion in the liver and kidneys to its active form, which is necessary for its various functions in the body.
Synthesis of Vitamin D in the skin declines with age.

VITAMIN-D DEFICIENCY:

Traditionally, Vitamin D deficiency has been associated with rickets, a disease in which the bone tissue doesn't properly mineralize, and bones can become thin, brittle, or misshapen leading to soft bones and skeletal deformities.
Furthermore, vitamin D deficiency is associated with osteoporosis, an increased risk of falls, and fragility fractures. Sufficient vitamin D levels help prevent osteomalacia (softening of the bones) in adults.
In addition to its impact on bone health, research is increasingly highlighting the importance of vitamin D in protecting against various health issues. Recent studies have linked vitamin D deficiency to conditions such as cancer, cardiovascular disease, diabetes, autoimmune diseases, and depression.

CAUSES OF VITAMIN-D DEFICIENCY:

Vitamin D deficiency can occur for several reasons:

LOW VITAMIN-D IN DIET	Not meeting adequate levels of Vitamin D is more likely if one follows a strict vegan diet because most of the natural sources are animal-based
INADEQUATE EXPOSURE TO SUNLIGHT	People who shun the sun or apply sunscreen, are homebound, wear long robes, use head coverings, or have an occupation that prevents sun exposure can cause Vitamin D deficiency.
DARK SKIN	The pigment melanin responsible for skin color reduces the skin’s ability to make Vitamin D in response to sunlight exposure. Therefore, dark skin adults especially elders are at high risk of Vitamin-D deficiency.
KIDNEY DISEASE	The kidney converts Vitamin D into its active form. When people age, their kidneys are less able to convert Vitamin-D to its active form due to the lack of enzymes leading to the risk of Vitamin-D deficiency.
CONDITIONS THAT LIMIT FAT ABSORPTION	Vitamin D is a fat-soluble vitamin, and its absorption depends on the gut’s ability to absorb dietary fat. Medical conditions like some forms of liver disease, cystic fibrosis, celiac disease, Crohn’s disease, and ulcerative colitis hinder fat absorption and increase the risk of Vitamin D deficiency.
OBESITY	A higher BMI (Body Mass Index) above 30 is associated with lower release of Vitamin-D levels from fat cells, thus requiring larger doses of Vitamin-D supplements to maintain normal levels.
LIVER DISEASE	Liver disease can cause Vitamin-D deficiency due to the lack of certain enzymes to produce an active form of Vitamin-D that our body can use.
DRUG- INTERACTIONS	1. Medications such as phenobarbital, carbamazepine, dexamethasone, nifedipine, spironolactone, and clotrimazole induce hepatic enzymes which activate the degradation of Vitamin D. 2. Certain medications like laxatives can also lower Vitamin D levels. 3. Orlistat, the weight-loss drug can reduce the absorption of Vitamin D from food and supplements 4. Statins reduce cholesterol synthesis and may also reduce Vitamin D. 5. Steroids prescribed to reduce inflammation can impair Vitamin D metabolism.
WEIGHT-LOSS SURGERIES	Surgeries such as gastric bypass surgery done to reduce the size of the stomach and/or bypass part of the small intestines, make it difficult for our body to absorb Vitamins, leading to its deficiency.
INFANTS	Breastfed infants not receiving supplemental Vitamin-D or adequate sunlight exposure are at increased risk of developing Vitamin-D deficiency.

RECOMMENDED DAILY INTAKE OF VITAMIN-D FOR INDIANS BY INDIAN COUNCIL FOR MEDICAL RESEARCH (ICMR)

Age Group	Recommended Amount
Infants up to 12 months old	400 IU
Rest of the age group	600 IU
Pregnant and breastfeeding people	600 IU

Some studies recommend a dose of 600 IU/day for women below 70 years and 800 IU/day over 70 years.

A DIET RICH IN VITAMIN-D

Most of the natural sources of Vitamin D are animal-based and vegan-based diets are limited.

Animal-based Diet

Vegan Diet

SYMPTOMS:

MAJORLY AFFECTED POPULATION:

PREVALENCE OF VITAMIN-D DEFICIENCY:

Vitamin D deficiency is a common global issue. About 1 billion people worldwide have Vitamin-D deficiency.
Over 80% of adults in India are reported to be Vitamin D deficient against 35% in the United States. Moreover, Vitamin-D deficiency exceeds over 90% with age in the elderly population in India.
High prevalence in India has been reported due to a combination of factors including inadequate exposure to sunlight, vegan diet, skin pigmentation, pollution, genetic polymorphisms, and body fat percentage.
Moreover, Indian dietary factors like inadequate calcium intake, high phytates, and phosphates, intake of caffeine, etc increases the risk of Vitamin D deficiency.

DIAGNOSIS:

Vitamin-D blood tests are performed to check the level of Vitamin-D in our body.
The test involves the procedure of taking out the blood sample for evaluation at the lab.
Healthcare providers advise the test based on medical conditions, risk factors, and symptoms.
There are two types of Vitamin-D tests, but the most common is the 25-hydroxy Vitamin-D.

TREATMENT:

The treatment modality for Vitamin-D deficiency is to ensure that Vitamin-D reaches the adequate level required for the body and then maintain it.
Eating more foods containing Vitamin-D and getting more sunlight will be advised by the Healthcare Provider, in addition to the likely recommendation of taking Vitamin-D supplements.
Our body more easily absorbs D3 than D2.
There are two types of Vitamin-D tests, but the most common is the 25-hydroxy Vitamin-D.

Vitamin Deficiency