Vitamin D deficiency: the most effective dietary supplements

Vitamin D, often called the 'sunshine vitamin', is a unique fat-soluble vitamin that resembles steroid hormones. Synthesized by the body from cholesterol under the action of the sun's ultraviolet (UV) rays, it plays a fundamental role in regulating the absorption of calcium and phosphorus, elements essential for bone health.

Physiological Role of Vitamin D

Vitamin D plays a central role in regulating calcium and phosphorus, two minerals essential for the formation and maintenance of strong bones and teeth. nnOnce synthesized in the skin or ingested in food, vitamin D is converted by the liver and kidneys into its active form, calcitriol. Calcitriol acts like a hormone by facilitating intestinal calcium absorption and by regulating its reabsorption by the kidneys. nnMoreover, vitamin D plays a key role in muscle function and in modulating the immune system, notably by stimulating the production of cathelicidin, an antimicrobial protein that helps protect the body against infections, particularly in the respiratory tract.

Dietary Sources of Vitamin D

Although the human body can synthesize vitamin D through sun exposure, certain dietary sources are also crucial for maintaining adequate levels, especially during the winter months or in regions where sun exposure is limited. nnAmong foods rich in vitamin D are the fatty fish such as salmon, tuna, and sardines, as well as cod liver oil. The eggs, the liver, and fortified dairy products are also good sources. Some mushrooms exposed to ultraviolet rays can contain vitamin D2, offering a plant-based alternative.

Consequences of Vitamin D Deficiency

A deficiency in vitamin D can have serious health consequences. Among the symptoms and associated conditions are:nn• Bone demineralization: In adults, vitamin D deficiency can lead to bone weakness, pain, and increased bone fragility, including osteoporosis.nn• Rickets: In children, severe deficiency can cause rickets, characterized by bone deformities due to inadequate mineralization.nn• Cardiovascular Diseases: Insufficient vitamin D levels are linked to an increased risk of cardiovascular diseases, such as hypertension, atherosclerosis, and coronary artery disease.nn• Type 2 Diabetes: Vitamin D plays a role in insulin regulation, and deficiency may promote the development of type 2 diabetes.nn• Immune and Autoimmune Disorders: Vitamin D deficiency is associated with an increased risk of autoimmune diseases, notably multiple sclerosis, type 1 diabetes, and inflammatory bowel diseases.nn• Cancers: Low levels of vitamin D are linked to a higher risk of certain cancers, including breast, prostate, colon, and skin cancers. While research continues, these associations suggest the importance of maintaining adequate vitamin D levels to potentially reduce the risk of developing these diseases.nn• Neurodegenerative Diseases: Some studies have suggested a link between vitamin D deficiency and an increased risk of neurodegenerative diseases, such as Alzheimer's disease and other forms of dementia.nnPopulations at risk for deficiency include the elderly, those with limited sun exposure, individuals with dark skin, as well as those who follow a diet low in vitamin D or suffer from intestinal absorption disorders.

Prevention of Deficiencies

To prevent vitamin D deficiency, it is essential to combine moderate sun exposure with a diet rich in vitamin D sources. In cases of increased risk of deficiency or if vitamin D levels are insufficient, supplementation may be necessary. nnRecommended doses vary depending on age, lifestyle, and individual needs. For healthy adults, supplementation of 600 to 800 IU per day is often advised, while higher doses may be necessary to correct an existing deficiency.nn