VITAMIN D

The best sources of vitamin D:

ProductServing sizeCaloriesAmount (mcg)DRI/DV (%)Nutrient densityQuality
Shrimps120g112162.440.66.5Very good
Sardines120g191250.262.65.9Very good
Skimmed milk1 cup12197.624.43.6Very good
Cod120g11963.515.92.4Good
Eggs16828.85.71.5Good

FUNCTIONS

The beneficial effects of products rich in Vitamin D:

  • Participate in maintaining the strength and the health of bones and teeth;
  • Regulate the growth and the activity of the bones;
  • Prevent the excessive inflammatory activity of the immune system.

Which indications require consumption of more products rich in Vitamin D?

  • Reduced bone density, frequent fractures, soft bones;
  • Deformations of the bones or delayed growth and development in children;
  • Not being exposed to sun;
  • Dark complexion.

THE IMPACT OF STORAGE, PROCESSING AND COOKING

Vitamin D is relatively stable compound. Neither cooking nor long-term storage can significantly reduce its quantity in the products.

PUBLIC HEALTH RECOMMENDATIONS

In 1997, the National Academy of Sciences (NAS) published the new values for adequate intake  (AI) of Vitamin D. The recommended values are as follows:

  • Infants and children: 5mcg (200 IU)
  • Teenagers: 5mcg (200 IU)
  • 19 – 50 years: 5mcg (200 IU)
  • 51 – 70 years: 10mcg (400 IU)
  • 70 years +: 15mcg (600IU)
  • Pregnant and lactating women: 5mcg (200 IU)

A Daily Value (DV) of 400 IU is the reference value you will see on food and supplement labels. These RDA recommendations are meant to prevent symptoms related to deficiency even in those with minimal sunlight exposure.

If you want to know the status of Vitamin D in your system, ask your doctor to check the level of 25(OH)D3 in your blood, which is the basic form of vitamin D in the blood system.

WHY DO WE NEED PRODUCTS RICH IN VITAMIN D?

At the beginning of the 20th century, scientists discovered that rickets could be prevented by a compound isolated from the oil of cod liver. This compound was called factor D soluble in fat, and it was actually the vitamin D. It was also known as calciferol because it was discovered that it stimulates the absorption of calcium in the bones. It is known that without sufficient amount vitamin D, the absorption of calcium from the food we take is barely 1 – 15%. When the level of vitamin D is adequate, then the absorption is 30 – 80%. Given the fact that vitamin D is so important for the development and strength of the bones, many products are fortified with vitamin D to ensure that children consume sufficient quantity of it.

There are two basic types of vitamin D. The ergosterol is the main element of this vitamin in the plants. The cholesterol is the main element of vitamin D in people. Under the influence of sunlight, the ergosterol is converted into vitamin D2 or ergocalciferol.

The same thing happens when an ultraviolet ray falls on our skin: the cholesterol converts into Vitamin D3 or cholecalciferol.

Vitamin D participates in maintaining normal levels of calcium in the blood by having impact on its absorption and storage. Vitamin D supports the absorption of phosphorus as well. It also regulates the production of certain proteins which bind with the calcium, and have effect in the bones and the kidneys.

By consuming products rich in vitamin D we increase the body consumption of this important nutrient as well as other nutrients which act synergistically with it. This process stimulates its physiological function and contributes to optimal health.

THE BENEFICIAL EFFECTS OF THE VITAMIN D ON THE HEALTH

Maintains the calcium level in the blood

Although it is categorized as a vitamin soluble in fat, vitamin D mostly acts as a hormone. Calcitriol, metabolically the most active form of vitamin D, in cooperation with parathyroid hormone PTH maintains the normal levels of calcium in the blood. Calcitriol intensifies intestinal absorption of calcium, increases the reabsorption of calcium in the intestines and stimulates its release from the bones, which increases its levels in the blood. On the other hand, when the calcium levels are high, the calcitriol reduces its intestinal absorption and stimulates the bones to absorb the calcium, which decreases its levels in the blood. Given the fact that it participates in the calcium metabolism, vitamin D is not important just for the bones’ health, but for the teeth health as well. Studies revealed that vitamin D deficiency in people older than 50, increases the risk of periodontitis.

Supports the proper functioning of the immune system and prevents excessive inflammation

Vitamin D regulates the functioning of the immune system by preventing the excessive or lengthy anti inflammatory response. Our immune cells, especially the active T-cells, have receptors for vitamin D. This is very important for the autoimmune diseases, because the T-cells are responsible for the inflammation. Preliminary studies show that the anti-inflammatory activity of vitamin D has a positive effect on a range of diseases, among them hypertension, type 1 diabetes and psoriasis.

Regulates the cells activities

It’s been known for years that vitamin D, in the form of calcitriol, participates in the regulation of the cell activities. But only recent studies confirmed that the membrane of cell nuclei has receptors for vitamin D. It is considered that the divisions of cells and their natural death depend on vitamin D. Also most of the organs which depend on minerals, including bones, kidneys, intestines and the parathyroid gland, depend on the availability of vitamin D as well. Given the fact that cell cycles play an important role in cancer development, then optimal intake of vitamin D could be crucial for the prevention and/or treatment of various cancers.

WHAT ARE THE REASONS FOR VITAMIN D DEFICIENCY AND ITS SYMPTOMS?

People who are rarely exposed to sun should include quality sources of vitamin D in their diet. People from the northern areas; people who use sunscreen lotions and cover the whole body with clothes are at risk of vitamin D deficiency. People with dark complexion are also at risk of vitamin D deficiency because their skin contains more melanin, a pigment which reduces the skin’s ability to produce vitamin D under the influence of the sunlight. Babies, whose only food is breast milk, can be at risk of vitamin D deficiency if their mothers do not have sufficient amount of it in the system.

Vitamin D is soluble in fats, and therefore a diet that is low in fat and/or the presence of a certain disease which reduces the fats absorption can cause the deficiency of this vitamin. There are also certain circumstances which unable the conversion of the inactive forms of vitamin D into calcitriol, such are the diseases that attack the parathyroid gland, liver, or the kidneys.

Vitamin D deficiency results with reduced absorption of calcium and phosphorus. Prolonged deficiency has a negative impact on the mineralization of the bones. In infants and children it leads to rickets, a condition characterized by deformation of bones and slow growth and development. In adults it could lead to decrease in bone density (osteopenia), bone pain and/or softening of the bones (osteomalacia).

CAN WE CONSUME TOO MUCH VITAMIN D?

Excessive intake of vitamin D can be toxic. The toxic amount can be consumed through products of plant (D2) and animal (D3) origin. The symptoms of the poisoning include loss of appetite, nausea, vomiting, hypertension, impaired renal function and development slowdown.

In 1997 the FDA also established the Tolerable Upper Intake Limit (UL) for vitamin D. The values are as follows: infants 0 -12 months: 25mcg per day; children and adults: 50mcg per day; pregnant and lactating women: 50mcg per day.