Vitamin D
Vitamin D helps the body absorb and use calcium and phosphorus, thus contributing to the formation and maintenance of bones and teeth. It also plays a role in the normal functioning of the immune system.
Vitamin D is produced by the body when the skin is exposed to sunlight. It is also found in certain foods.
There are two forms of vitamin D:
- Vitamin D2
- Derived from plant sources (e.g., certain mushrooms)
- Vitamin D3
- Derived mainly from animal sources (e.g., fatty fish)
- Used to fortify certain foods (e.g., certain cereals, orange juice)
- Produced by the skin upon exposure to sunlight
- Found in most vitamin and mineral supplements with vitamin D
To function, both forms of vitamin D must be converted in the liver, and then in the kidneys, to their active form.
Other names
- Cholecalciferol
- Colecalciferol
- Calciferol
- Ergocalciferol
Sources
Vitamin D is obtained predominantly from sun exposure, dietary sources, and supplements. Health Canada recommends that individuals get vitamin D from foods or supplements every day to meet their daily requirements.
Few foods naturally contain vitamin D, which is why some are fortified.
- Fatty fish, egg yolks, and certain mushrooms naturally contain decent amounts.
- Fortified milk, margarine, and plant-based beverages are also good sources of vitamin D.
Some yogurts and cheeses can be made with fortified milk, but they contain less vitamin D than the milk in its original form.
Approximate vitamin D content
| Food | Portion | Content |
|---|---|---|
| Cod liver oil | 15 mL | 32 mcg |
| Greenland halibut, cooked | 75 g | 26 mcg |
| Swordfish, cooked | 75 g | 19 mcg |
| Canned pink salmon, with bones | 75 g | 10.9 mcg |
| Maitake mushrooms, raw | 125 mL | 10.2 mcg |
| Atlantic salmon, cooked | 75 g | 5.1 mcg |
| Atlantic herring, cooked | 75 g | 4 mcg |
| Trout, cooked | 75 g | 3.8 mcg |
| Food | Portion | Content |
|---|---|---|
| Tilapia, cooked | 75 g | 2.8 mcg |
| Cow's milk | 250 mL | 2.7 mcg |
| Soft margarine | 15 mL | 2.5 mcg |
| Whole eggs, cooked, scrambled | 2 large | 2.2 mcg |
| Soy beverage, fortified | 250 mL | 2.2 mcg |
| Yogurt, fruit-flavoured, fortified | 175 mL | 1.4 mcg |
| Shiitake mushrooms, dried | 10 | 1.4 mcg |
| Canned light tuna, in water | 75 g | 0.9 mcg |
Recommended Daily Allowance (RDA)
The RDA for vitamin D is the daily vitamin D intake required to meet the needs of most healthy individuals.
Vitamin D Requirements
| Age | Men | Women |
|---|---|---|
| 1-18 years old | 15 mcg (600 IU) | 15 mcg (600 IU) |
| 19-50 years old | 15 mcg (600 IU) | 15 mcg (600 IU) |
| 51-70 years old | 15 mcg (600 IU) | 15 mcg (600 IU) |
| Age | Men | Women |
|---|---|---|
| >70 years old | 20 mcg (800 IU) | 20 mcg (800 IU) |
| Pregnancy and breastfeeding, all ages | 15 mcg (600 IU) |
Deficiency
The body can store enough vitamin D to last a few months. Deficiency can lead to reduced calcium absorption, which in turn can lead to brittle bones.
Children who are vitamin D-deficient can develop a condition known as rickets, where the bones soften and may become deformed.
Other harmful consequences of vitamin D deficiency include osteoporosis, loss of muscle mass, and reduced immune function.
Toxicity
Sun exposure and dietary consumption are unlikely to cause vitamin D excess. If an individual is taking vitamin D supplements, tests can be done when indicated to check their blood vitamin D levels.
Too much vitamin D can lead to increased calcium levels in the blood. Calcium can subsequently become deposited in certain tissues, including in the kidneys, heart, blood vessels, and lungs. Vitamin D toxicity is also associated with the following symptoms:
- Drowsiness
- Weakness
- Headaches
- Loss of appetite
- Nausea and vomiting
- Constipation
Supplements
The vitamin D produced by the skin through sun exposure and naturally found in food isn't always enough to meet a person's daily requirements. This is why it's sometimes necessary to take supplements.
According to Health Canada, everyone over the age of 51 should take a daily vitamin D supplement.
It's best to take vitamin D supplements with a meal, as the presence of fat in the gut improves their absorption.
To find out whether you should be taking a vitamin supplement, talk to your health care provider.
Always watch your diet:
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The patient information leaflets are provided by Vigilance Santé Inc. This content is for information purposes only and does not in any manner whatsoever replace the opinion or advice of your health care professional. Always consult a health care professional before making a decision about your medication or treatment.