Our immune system tends to defend our bodies against any foreign or invading organism. The immune system promotes the protective immunity of the body while it maintains self-tolerance.
The deficiency of vitamin D can significantly affect the immune system. With this deficiency, our body gets more susceptible to diathesis and infections.
What is Vitamin-D?
Vitamin D belongs to the category of fat-soluble vitamins, which play its role in immune cells’ functioning. It protects your body from different illnesses and diseases. Vitamin D has some types as D2 and D3.
D2 is ergocalciferol, and D3 is calcitriol. Both of these forms can be available in your diet. However, the number of foods (naturally occurring), which contain these forms, is low.
Classically, vitamin D helps in promoting the homeostasis of calcium and promotes bone health. Vitamin D can also enhance the calcium absorption in small intestines and stimulate the differentiation of osteoclasts in the bone.
In humans, the main source of vitamin D is either through the diet or skin synthesizes it. In the human body, the production of vitamin D occurs at the cutaneous level after UVB exposure.
Melanin tends to absorb the UVB light and inhibits the vitamin D synthesis from 7-dihydro cholesterol. In the initial stages, a compound of vitamin D is in an inactive form. In the next step, hydroxylation of this compound occurs in the liver for the formation of 25 OH vitamin D3, also known as 25D.
25D is another inactive form, but it can measure vitamin D levels in an individual reliably. The active compound of vitamin D comes into being in the kidneys. In kidneys, this compound converts to 1,25 D (1,25 dihydroxy Vitamin D).
Role of vitamin D in boosting immunity:
Before the invention of antibiotics, the medical field was unknowingly using vitamin D for various infections and tuberculosis. For tuberculosis, the patient was sent into direct sunlight exposure to kill the pathogens responsible. Another treatment option was Cod liver oil. This oil was effective in treating TB and was a protection against several infections.
According to several clinical data, vitamin D has evidence-based effectiveness in boosting immunity.
According to one study, people suffering from vitamin D deficiency were more likely to suffer from URTIs (upper respiratory tract infections). Several other studies also supported the role of vitamin D in infection rates.
One paper published a relationship between vitamin D deficiency and increased risk of influenza, HIV, and bacterial vaginosis.
Several autoimmune diseases as DM (diabetes mellitus), MS (multiple sclerosis), RA (rheumatoid arthritis), SLE (systemic lupus erythematosus), and IBD (inflammatory bowel disease) are having an association with low levels of vitamin D. In more than 50% of the SLE patients had a severe deficiency of vitamin D.
How vitamin D boosts immunity?
Vitamin D plays a role in immunity due to its effects on the body’s natural immune system. In our body, macrophages tend to recognize the source of infection through specialized cells as TLR (toll-like receptors). Through these cells, a cascade of events occurs. This cascade produces peptides that stimulate a strong bacteria-killing activity as beta defending and cathelicidin. These peptides help in disrupting the bacteria cell membranes and improve the anti-microbial action.
Vitamin D plays a significant role here. The transcription of bactericidal activity (cathelicidin) requires enough amount of 25 D (vitamin D). Availability of an adequate amount of vitamin D helps start the cascade and stimulates the anti-microbial activity.
Vitamin D and immunology:
Vitamin D helps in:
- Inhibition of proliferation of B cells
- Blocking the immunoglobulin secretion and B-cells differentiation
- Suppressing proliferation of T cells
- Facilitation of T regulatory cells induction
- Decreased inflammatory cytokines production
- Increased anti-inflammatory cytokines production as IL-10
- Inhibition of inflammatory cytokines as TNF-alpha, IL-12, IL-8, IL-6, and IL-1
Dosage of vitamin D supplementation:
- The RDA values for vitamin D are 15mcg (600 IU) for people till 70 years of age
- 20mcg or 800 IU for people older than 70 years
- RDA 20 mcg or 600 IU for women who are breastfeeding
- For autoimmune diseases, RDA is 400 IU per day for the prevention of multiple sclerosis
- For the prevention of osteoporosis, the recommended dosage is 400 to 2000 IU per day
Vitamin D is a significant nutrient of the body. Most f the time, our body needs these nutrients from an external source. There are several reliable vitamin D supplements available in the markets. Vitamin D can boost immunity and prevent several immunity-related illnesses. Before opting for vitamin D supplementation, you should ask your physician for further guidance.