Vitamin D

27 November 2023

Vitamin D: Benefits, deficiency, sources, and dosage. Vitamin D is involved in bone growth, and this element is also beneficial for the heart and muscles. What are the signs of vitamin D deficiency? How to take advantage of its benefits and ensure its contributions? How do you recognize side effects and vitamin D overdose?

What is Vitamin D?

Vitamin D, also known as calciferol, is a pro-hormone primarily involved in bone growth. Its origin is twofold, that is to say, that it is synthesized by the body and introduced into it through food.
The synthesis of vitamin D is stimulated by the exposure of our skin to ultraviolet solar rays, in particular UVB. Minimal exposure to the sun is therefore necessary for the body to produce it.

Vitamin D has an action on several functions of the body:

It intervenes in the absorption of calcium and phosphorus at the intestines level. It ensures the mineralization of bones, joints thus influencing bone growth. Identified in 1922 by Elmer McCollum as part of the care provided against rickets (disease-causing retardation of bone growth due to a vitamin D deficiency ), it has made it possible to fight this disease effectively.
It limits bone fractures, ensuring the strength of bones and teeth.
It limits the appearance of osteoporosis in the elderly. This disease causes a decrease in bone density, which weakens the body's bones.
It strengthens muscle tone by promoting the renewal of muscle fibers and muscle contraction during movement.
It provides a protective function of neuronal cells and delays cognitive decline.
It would also ensure protective effects against cardiovascular diseases, diabetes and certain cancers. However, these latter functions have not been formally proven.

The benefits of vitamin D

The benefits of vitamin D stem from its role in the body. Essential for ensuring bone growth and health, vitamin D helps regulate blood calcium levels and phosphorus absorption. If the body were to lack vitamin D, the calcium would be eliminated in the urine by the kidneys.

Therefore, it makes it possible to capture calcium and "fix" it on the bones to ensure their maturation.

Vitamin D deficiency can cause rickets in children (growth retardation) and osteomalacia (decrease in bone density), osteoporosis (weakening of the bones due to the reduction in their density ) or hypocalcemia (blood calcium level too low) in adults.
Therefore, it is essential not to neglect food intake to benefit from vitamin D and to regularly check the blood level of this vitamin in the body.
Studies are currently underway to demonstrate the beneficial effects of vitamin D on reducing the progression of certain cancerous diseases (especially colon cancer), limiting the onset of multiple sclerosis Alzheimer's disease, and reducing several cardiovascular disorders and seasonal depression.
Note: Exposure to the sun for about 15 to 30 minutes, twice a week, ensures sufficient vitamin D intake in an adult. We do not hesitate to expose ourselves to the sun when we have the opportunity to promote the synthesis of vitamin D. We do not forget to protect our skin by applying a suitable sunscreen to do this.

Deficiency symptoms vitamin D

It is interesting to highlight the symptoms that can alert you to a possible deficiency to benefit from vitamin D supplementation. It would help if you reacted when you noticed the following signs:

Muscle pain, bone pain
Joint pain
Back pain
chronic fatigue
Temporary depression
Being sick often or getting infections more often
Impaired healing
Frequent falls (especially in the elderly)

It is possible to carry out a blood test to confirm the deficiency by taking a simple blood test. This physical examination makes it possible to check the level of vitamin D in the blood and thus determine the organism's needs.

Recommended nutritional allowances

Essential at all stages of life; however, vitamin D needs vary according to the individual's growth stages. As infants, young children and adolescents are in the process of growth, their vitamin requirements will be higher, for example.
The nutritional references or recommended intakes of vitamin D are expressed in micrograms (µg) or international units (IU). They correspond to:

Newborns/babies up to 12 months: 20/25µg or 800/1000 IU per day
Children aged 1 to 3 years: 10 µg/day, i.e., 400 IU/day
Children aged over 36 months, adolescents from 12 to 18 years old and adults: 15 µg/day, i.e., 200 IU/day
Children aged 1 to 3 years: 10 µg/day, i.e., 400 IU/day
Children aged over 36 months, adolescents from 12 to 18 years old and adults: 15 µg/day, i.e., 200 IU/day
Over 75 years old: 10 to 15 µg/day, i.e., 400/600 IU/day

Pregnant or breastfeeding women should be careful with their vitamin D intake. Indeed, some scientists believe that vitamin D helps prevent pre-eclampsia and gestational diabetes.

The recommended intakes of vitamin D for pregnant women are 10 µg/day, i.e., 400 IU/day. Namely: to avoid vitamin D deficiency in young children, children aged 0 to 18 months benefit from vitamin supplementation in France. This action makes it possible to limit the appearance of cases of rickets and promotes good growth in children.

Top 5 Foods That Contain Vitamin D

A few reminders: the vitamin is synthesized by the body (from the epidermis) and provided by food. It exists in two distinct forms: vitamin D2, present in certain plant elements or vitamin D3, present in animal meat. Vitamin D2 is also called ergocalciferol, while vitamin D3 is referred to as cholecalciferol.
Vitamin D is present in a few foods, and however, it is possible to add products rich in vitamin D to your diet. Especially in winter, when sunny days are rarer, our exposure is reduced.

1. Cod liver oil

Cod liver oil brings back bad memories to our elders. Their grandmothers gave a teaspoon of cod liver oil to their children to ensure their good health. And they weren't necessarily wrong!
Cod liver oil is very rich in vitamin D. It contains 250 µg per 100g. A teaspoon provides 37.5 µg of vitamin D, three times the recommended daily allowance! You might as well add it to the menu to avoid deficiencies. Cod liver contains 100 µg of vitamin D per 100 g.

2. Oily fish

Oily fish have many virtues and are excellent for your health. They contain omega 3, good for the brain, sleep or limit stress, and vitamin D.
Do not hesitate to add sardines, tuna, mackerel or salmon to your menus to benefit from their benefits.
To avoid composing dishes that are too rich in fat, it is preferable to eat this type of fish grilled, baked or en papillote, accompanied by vegetables and starchy foods.

3. Eggs

Eggs, rich in protein, are beneficial for the brain. They also contain vitamin D (0.94 µg/egg).
Eggs are ideal for evening meals. To eat hard, in salad or omelet, precisely a soup, green vegetables, or a green salad.

4. Milk and dairy products

Milk, butter, yogurt, and cottage cheese contain vitamin D. Some dairy products are fortified with vitamin D and marketed for their growth and bone strength benefits. It is a marketing argument, indeed, but proven.
Dairy products efficiently complete your daily menus to be consumed at breakfast, lunch or dinner for dessert or a snack (a glass of hot milk before bedtime).

5. Mushrooms

Mushrooms, especially chanterelles, morels or shiitake mushrooms (Japanese mushrooms), are also a source of vitamin D. The advantage of these foods is that they are low in calories. It can be consumed in large quantities.
Cooking the mushrooms in a frying pan, in a vegetable oil rich in omega 3, makes it possible to compose succulent accompaniments for your meat and fish. They can be eaten with a portion of starches to craft nutritious and healthy meals.

Dangers and side effects, vitamin D overdose

We now know the effects of vitamin D deficiency. What happens when vitamin D intake is too high? What are the risks of overdose?

Vitamin D overdoses have become rare, as intakes are better controlled.

However, overdoses can cause hypercalcemia (too high calcium levels in the blood), leading to hypercalciuria (too high calcium levels in the urine). Excessive blood calcium concentration can lead to kidney stones ("small pebbles" present in the kidney).
These stones can cause significant pain and cause complications such as renal colic. Calcium deposition in the kidneys is called nephrocalcinosis, a kidney disease that can also result from vitamin D overdose.

Hypercalcemia appears when a subject is exposed to doses greater than 40,000 IU/day. Symptoms of vitamin D overdose are:

Nausea or vomiting
Asthenia (fatigue)/drowsiness
Headaches (headaches)
Dehydration/great thirst
Muscle weakness and pain
Anorexia
Increased blood nitrogen level (azotemia)

To avoid deficiencies or overdoses, it is essential to assess the level of vitamin D in the blood by performing regular blood tests. These assessments are carried out on medical prescriptions.

Healthy Food Recipes

Min menu

Pages