The Importance of Vitamin D: Excess and Deficiency Equally Dangerous

Excess and deficiency of vitamin D are equally dangerous for the human body. International-class Russian nutritionist Natalya Tyurkina told the sb.by portal about what functions this vitamin performs and what foods are rich in it:

– Vitamin D, also called calciferol, is produced in our bodies by exposure to ultraviolet rays from sunlight and can also be obtained from food.

Functions of Vitamin D

Nutritionist
Natalya Tyurkina – Vitamin D is involved in a large number of metabolic reactions in the body. Its main function, by the way, proven by numerous studies, is to enhance the absorption of calcium, as well as iron, magnesium, phosphorus and zinc in the intestines. Vitamin D is also involved in strengthening and restoring muscle tissue (in combination with unsaturated fatty acids), emphasized Natalya Tyurkina.

Without enough vitamin D, bones can become thin, brittle, and brittle. Sufficient intake of the vitamin in the body prevents rickets in children and osteomalacia (softening of bones) in adults. Together with calcium, vitamin D helps protect older adults from osteoporosis.

An overdose of vitamin D is no less dangerous than its deficiency. Excess can increase the level of calcium in the blood (so-called hypercalcemia), which in the long term can lead to damage to the heart, lungs, blood vessels and kidneys.

Vitamin D Dosages

– Consumption standards vary in each country. For example, the National Institutes of Health (NIH) recommends receiving 600 IU per day from one year to 70 years, and 800 IU daily from 70 years of age, since intestinal absorption worsens with age. According to Russian recommendations of 2015, the daily preventive dose of vitamin D in food for people 18–50 years old is at least 600–800 IU, explained Natalya Tyurkina.

Normal levels of vitamin D in the blood:

• 25(OH)D concentration more than 30 ng/ml is normal;

• 25(OH)D concentration less than 30 ng/ml – deficiency;

• 25(OH)D concentration less than 20 ng/ml is a deficiency.

An overdose of vitamin D is possible starting from a concentration of 100 nmol/l; of course, the toxic concentration is 200 nmol/l.

Vitamin D is a fat-soluble compound. Fats supplied with food are essential for its absorption in the intestines. Vitamin D reserves accumulated by the body in fat depots during the summer can gradually be used up during the winter months.

If you are a city dweller, spend most of your time indoors, rarely get exposure to the sun, or wear clothing that covers most of your skin, you should take extra vitamin D all year round to avoid vitamin D deficiency.

Residents of temperate (northern) climates with few sunny days and a low UF index cannot obtain enough vitamin D naturally. They are recommended to replenish its deficiency from October to March.

According to expert organizations, to ensure the required dose of vitamin D, it is necessary to be in the sun every day from 10 am to 4 pm or at least twice a week with sunlight on the face, arms, and legs. For people with fair skin, a five-minute sunbath is enough.

It is important to remember that excessive sun exposure carries a risk of skin cancer.

People at risk for vitamin D deficiency include people with dark skin (as dark skin blocks its production), obese people (vitamin D is stored in adipose tissue), people on low-fat diets, pregnant and lactating women and children under the age of 5 years (the reason is the increased need for vitamin D due to growth and development), as well as older people (aging skin synthesizes less vitamin D).

Foods containing vitamin D

– Remember that the decision to take supplements must be made with a specialist, and treatment should begin with determining the level of vitamin D in the blood to avoid overdose. To prevent vitamin D deficiency, it is enough to be in the sun every day and consume foods containing vitamin D, comments the nutritionist.

Vitamin D is naturally present in foods, and nowadays you can also find foods fortified with vitamin D (milk, eggs, mushrooms). In some cases, fortified foods and nutritional supplements are beneficial. For example, when it is impossible to meet the requirements for one or more nutrients.

It is important to consider the concentration and portion of vitamin D fortified foods to avoid getting too much.

It is extremely difficult to get an excess of vitamin D from ordinary foods: the body independently regulates its concentration. But they perfectly help fill the daily need for this vitamin. In addition, food provides many nutrients and other components that provide health benefits.

The daily requirement of vitamin D can be met with the following products.

♦ Fish, seafood, especially fish liver (salmon, tuna, mackerel, sardines). These are one of the best natural sources of vitamin D, and are also combined with natural Omega-3 fatty acids. This is why it is so important to add fish to your daily diet or eat at least 2 servings of oily fish per week. Research shows that fish raised in nature has more vitamin D – about 1000 IU per 100 g. That is, a serving of wild salmon (this includes sockeye salmon, coho salmon, chinook salmon, chum salmon) completely covers the daily requirement for vitamin D. But farmed fish is less valuable: it contains only 250 IU of vitamin per 100 g.

♦ Beef, pork liver, cheese, egg yolks. The amount of vitamin D in the yolk depends on how much time the chickens spent in the sun, as well as the vitamin D content of their feed. The yolk of free-range chicken eggs contains 3–4 times more vitamin D. Additionally, if chickens have been fed a diet fortified with vitamin D, the yolk can contain up to 6,000 IU of vitamin D.

♦ Mushrooms are an excellent plant source of vitamin D. Like humans, mushrooms are able to synthesize vitamin D when exposed to the sun. And in decent quantities: sometimes up to 2300 IU per 100 g. But this only applies to mushrooms that had access to sunlight or artificial ultraviolet radiation. Those mushrooms that are grown under standard commercial conditions – in the dark – cannot serve as sources of vitamin D.

List of some sources of vitamin D:

• cod liver (15 g) – 600 IU (recommended daily dose in a tablespoon);

• wild salmon (100 g) – 600–1000 IU;

• farmed salmon (100 g) – 250 IU;

• sardines (100 g canned) – 300–600 IU;

• mackerel (100 g) – 300–1700 ME;

• fresh herring (100 g) – 300–1600 IU;

• pickled herring (100 g) – 270 IU;

• red caviar (100 g) – 320 IU;

• tuna (100 g) – 250 ME;

• cribs (100 g) – 150 ME;

• oysters (100 g) – 320 IU;

• milk fortified with vitamin D (1 glass 250 ml) – 100–140 IU;

• egg (1 yolk) – 44 IU;

• beef liver (100 g) – 48 IU;

• chanterelles (100 g) – 270 ME.

To meet the body’s needs for vitamin D, it is enough to regularly include fish and a variety of animal and plant sources of this vitamin in the diet, as well as be in the sun for 15-30 minutes a day.

Photo: freepik.com

Previously we wrote about the functions of calcium and signs of its deficiency in the body.

2024-01-04 18:51:00

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