Introduction:
Vitamin D is also referred to as calciferol. It is a fat-soluble vitamin obtained from exposure to the sun and is also present in certain foods and supplements. It is produced in the body when ultraviolet (UV) rays strike the skin and trigger vitamin D synthesis.
It is biologically inert and requires hydroxylation in the body to get activated. The first step of hydroxylation occurs in the liver, during which vitamin D gets converted into calcidiol [25-hydroxyvitamin (OH) D]. The second step of hydroxylation occurs in the kidneys, which results in the formation of the physiologically active form known as calcitriol (1,25-dihydroxy vitamin D). In foods and dietary supplements, vitamin D is available in two forms; ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3).
Why Is Vitamin D Important?
Vitamin D gets absorbed in the small intestine. Absorption occurs by passive diffusion, and the presence of fat in the gut also enhances this process. The serum concentration of hydroxyvitamin D is the main indicator of vitamin D status in the body.
Vitamin D primarily helps with calcium absorption in the gut, maintains serum calcium and phosphate concentrations, which enables bone mineralization, and also prevents tetany (involuntary contraction of muscles, that leads to muscle cramps and spasms).
Vitamin D is necessary for bone growth and remodeling processes, and it also helps in the reduction of inflammation and modulates cell growth, glucose metabolism, neuromuscular function, and immune function.
What Are the Signs and Symptoms of Vitamin D Deficiency?
Vitamin D deficiency occurs due to:
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Lack of vitamins in the diet.
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Malabsorption.
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Reduced exposure to sunlight.
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Inability of the kidneys and liver to convert vitamin D to its active form.
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Certain medications that may interfere with the conversion or absorption of vitamin D.
The symptoms of vitamin D deficiency include;
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Increased susceptibility to infections or frequent illness.
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Fatigue or tiredness.
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Bones can become thin and brittle, causing osteoporosis or fractures.
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Soft and weak bones in children are known as rickets and osteomalacia in adults.
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Back pain, joint and muscle pain.
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Impaired wound healing.
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Depression or anxiety disorders.
How Much Vitamin D Is Required by the Body?
The amount of vitamin D required depends on the age and condition of the individual. The recommended dietary allowance (RDA) of vitamin D is as follows;
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Pregnant and lactating females - 600 IU (International Units).
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From birth to 12 months - 400 IU.
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Children (one to 13 years) - 600 IU.
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Teenagers (14 to 18 years) - 600 IU..
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Adults (up to 70 years) - 600 IU.
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Adults (above 70 years) - 800 IU.
What Are Some of the Sources of Vitamin D?
A natural source of vitamin D and which can be easily obtained is from sunlight. Doctors recommend pregnant women, nursing mothers, and infants go outdoors, especially in the early mornings, for some sun exposure for the same reason. Some of the foods that naturally contain vitamin D include:
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Egg yolk.
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Mushrooms.
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Cheese.
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Beef liver.
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Fatty fish such as mackerel, salmon, tuna, etc.
Fortified foods that contain vitamin D include:
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Milk and fruit juices.
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Breakfast cereals.
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dairy products.
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Soy drinks.
Vitamin D is present in many multivitamin tablets, capsules, and suspensions.
Why Are Vitamin D Supplements Necessary During Breastfeeding?
Breast milk is considered the best source of nutrition for infants, and vitamin D is a normal component of human milk. The major forms, such as vitamins D2 and D3, are present in breastmilk. However, it is likely that consumption of human milk alone may not meet the daily requirements of vitamin D, as it contains approximately 25 to 78 IU/L. Some of the factors that may be considered for vitamin D supplementation during breastfeeding include:
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Breastfed infants require vitamin D to absorb calcium and phosphorus, and as too much sun exposure is not recommended for babies and supplements are the best way to prevent vitamin D deficiency.
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People living at high altitudes or in areas with dense cloud cover with limited sunlight.
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Areas of high pollution where exposure of infants or lactating mothers is not recommended.
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People with increased melanin pigmentation (darker skin complexions), may have reduced ability to produce vitamin D from the sunlight.
The American Academy of Pediatrics (AAP) recommends 400 IU (10 micrograms) of vitamin D per day for exclusively and partially breastfed infants, beginning shortly after birth until they are weaned and consuming a minimum of 1000 mL per day of vitamin D fortified milk. As vitamin D levels increase in the blood of the nursing mother due to an increase in sunlight exposure or dietary intake, the vitamin D in the breast milk also increases. As the infant grows, solid foods containing vitamin D can be provided, which would be beneficial for the growth. AAP also recommends supplemental vitamin D of 400 IU per day for all infants who are not breastfed and consume less than 1000 mL/day of fortified vitamin D milk.
Studies suggest that the breast milk of lactating mothers who take daily vitamin supplements has higher levels of vitamin D3 (2000 IU), which should be given to the infants as a daily vitamin D supplement as per the nutritional guidelines (400 IU). Exclusively breastfed infants are at a higher risk of developing rickets as compared to formula-fed infants. The goal of vitamin D supplementation is mainly to achieve around 30 mcg/L to 100 mcg/L (micrograms per liter) of serum 25-OH- vitamin D levels.
Studies also demonstrate that lactating females without vitamin D deficiency who take around 400 to 2000 IU of daily supplements have reported antirachitic activity in breast milk. When a lactating mother has a vitamin D deficiency and takes only 400 to 1000 IU of dietary supplements, the breastfed infant is likely to have deficient serum levels of vitamin D.
However, this can be improved when the mother increases her intake of vitamin D supplements. Research indicates that increasing the maternal supplementation with vitamin D results in an increase in the circulating levels of 25(OH) vitamin D in breastfed infants.
Conclusion:
Breast milk is considered the best source of nutrition for babies, and vitamin D is a vital component of it. Vitamin D deficiency is a universal issue of discussion, especially with regard to breastfed infants. Vitamin D content in human milk can be increased by maternal supplementation with oral vitamin D or by increasing the mother's sun exposure. A doctor can be consulted to recommend a vitamin D supplement for the infant or the mother to maintain the optimum levels and prevent further complications.
