Vitamin D, what it is for and where it is found

Vitamin D is classified as such despite acting as a hormone.It is essential for our body, but it is easy to be lacking.

This article on vitamin D was first published on December 22, 2009, and last edited on October 16, 2024.

• Vitamin D is a multifaceted and fundamental protagonist of human physiology.
• Obtainable mainly from sun exposure, vitamin D also comes from foods.
• The deficiency of this vitamin is certainly problematic.Investigating its levels is useful for prevention and treatment.

There vitamin D it is a true pillar of human health, covering biochemical roles that are anything but negligible.Its functions have been known for some time, although there is no shortage of more recently discovered pieces.Understanding its importance is a step forward towards well-being.

What is vitamin DThe term “vitamin D” identifies a group of components with a similar structure and classified, overall, as prohormones.Among these stand out the vitamin D2, of vegetal origin (and also known as “ergocalciferol”), and the vitamin D3 (or “cholecalciferol”), of animal origin.It is, importantly, about biologically active substances, capable of carrying out specific functions within the cell.

What is vitamin D used for?

At a macroscopic level, this vitamin favors intestinal absorption of calcium, ensuring adequate blood concentrations.By acting on the serum levels of this mineral, vitamin D is implicated in bone mineralization and is essential for bone growth and remodeling.Optimal levels of the same allow you to prevent rickets in children, osteomalacia in adults andosteoporosis in the elderly.But not only that.She is also involved in immune function and in the reduction of inflammation, as well as in neuromuscular function and in glucose metabolism.The effects on the life cycle of cells are no less important.In particular, it is capable of modulating genes associated with growth, proliferation and cell death.

Where to find vitamin D

To satisfy its need for vitamin D, the body implements specific mechanisms enzymatic conversion.In any case, the sources of this substance are not just food.

Sun exposure

Exposure to sunlight allows you to cover a large part of the necessary amount of vitamin D.The UVB radiation equipped with a specific wavelength (290-320 nanometers) they act at the epidermal level and convert a skin component (7-dehydrocholesterol) into pre-vitamin D3.This, in turn, acts as a precursor of biologically active vitamin D3.

In foods

Food sources of this vitamin are relatively few.They are among these fatty fish, (such as tuna and salmon), cod liver oil And seafood.Other sources are egg yolk, pork liver and, to a lesser extent, milk and derivatives.Undoubtedly interesting, too dried shiitake mushrooms are among the sources in question.There is no shortage of "fortified" foods in this sense, i.e. added vitamin D using specific technologies.These include milk, dried fruit And cereals, and report this characteristic on the label.

How much vitamin D to take

The recommended daily dose, to be taken through the diet, is established taking into account minimal sun exposure.In any case, it is a parameter that differs based on the age of the subject, starting from a minimum of 10 micrograms (400 IU) for infants up to 12 months of age, up to a maximum of 20 micrograms (800 IU) for elderly people over seventy.The contribution for the general population, from one to seventy years of age, is equal to 15 micrograms (600 IU).

There are no guidelines on the ideal times and methods of sun exposure.Some experts suggest that a daily exposure of half an hour, in the most favorable time slot (between 10am and 4pm), avoiding the application of skin protection, can guarantee excellent endogenous production of the vitamin.However, this is an aspect to be "taken with a pinch of salt", considering the known carcinogenicity of ultraviolet rays.Intuitively, the most appropriate way to expose yourself to the sun is through common daily activities (e.g.:walking down the street, riding a bicycle, etc.).

Vitamin D deficiency

Without sufficient amounts of vitamin D, bones may thin, become brittle or deformed.In children, a severe deficiency of the vitamin causes poor bone mineralization (rickets).In adults, the significant deficiency manifests itself with bone weakness, deformity And bone anomalies, resulting from incomplete mineralization.Symptoms associated with deficiency of this vitamin include bone and joint pain, but also muscle weakness And fatigue.In many other cases, the deficiency is asymptomatic, although not negligible.

The causes of the deficit are identified with the poor sun exposure and/or with insufficient food intake, but also with conversion problems at the kidney level or of intestinal absorption.The measurement of serum vitamin D, in the 25(OH)D form, is a very useful tool for assessing the extent of reserves:the optimal values ​​are between 20 and 40 ng/ml.Established deficiency levels are treated through targeted supplementation, with appropriate medical-nutritional supervision.

FAQs

• What is vitamin D used for? It is implicated in bone mineralization, immune function and the reduction of inflammation, but also in neuromuscular function, glucose metabolism and cell cycle regulation.
• What are the deficiency symptoms?Symptoms associated with vitamin D deficiency are bone and joint pain, as well as a state of muscle weakness and fatigue.In other cases, the deficiency is asymptomatic.
• In which foods is it found? It can be obtained from fatty fish, cod liver oil and seafood.Other sources are pork liver, egg yolk and milk derivatives.Dried shiitake mushrooms are also a source of this vitamin.
• What is the best way to take vitamin D?Much of the daily requirement of this vitamin can be met through exposure to sunlight.The dietary intake, however, has its own importance, and can be achieved by consuming specific foods, such as fatty fish, eggs and milk derivatives.The consumption of these foods, in any case, must be included in the context of a varied diet.
• What are the causes of vitamin D deficiency? Vitamin D deficiency can result from poor exposure to sunlight and/or an insufficient diet.Other causes, however, are attributable to intestinal absorption or enzymatic conversion problems.