Vitamin D, or the sunshine vitamin as it is also known, is a vital nutrient with a huge influence on the body. It is essential for healthy bones as it helps the body to absorb calcium but overall it influence all body mechanisms.
Vitamin D is part of the fat soluble secosteroids, with two main forms, vitamin D2 and vitamin D3. Vitamin D3 is obtained in the skin following exposure to direct sunlight or artificial sources with ultraviolet B light. It can be also naturally found in a number of foods. In certain countries, some foods including milk, margarine and flour are fortified with vitamin D. Further more, vitamin D is available as a supplement in the form of pills. Food such as fish, meat and eggs are rich in vitamin D and are “must have” part of the diet for people with vitamin D deficiency.
Vitamin D reaches the liver through the bloodstream and it is transformed into prohormone calcidiol. Later on when it is circulated, the calcidiol is converted into calcitriol, the naturally active form of vitamin D. This process takes place in the kidneys or by monocyte-macrophages. As calcitriol is synthesized by monocyte-macrophages, the calcitriol will work as cytokine, protecting the body against microbes.
On the other hand, when the synthesis takes place in the kidneys, calcitriol acts as a hormone, controlling for instance the calcium and phosphate level in the bloodstream, supporting the adequate mineralization, growth and reconstruction of the bone. Low vitamin D level can lead to weak, brittle bones, while an adequate level prevents rickets in children and osteoporosis and osteomalacia in adults. Additionally, vitamin D controls neuromuscular function and affects the genes that controls cell proliferation, differentiation and apoptosis.
Vitamin D Levels
Most relevant test for vitamin D levels is serum 25-hydroxyvitamin D test also known as 25(OH)D test. It shows the most accurate results of your vitamin D status in organism. If you took this test and you have results, you can compare it with deficient, normal, optimal, therapeutical or excessive amounts the data bellow.
< 20 ng /ml (< 50 nmol/l)
20-56 ng/ml (50-140 nmol/l)
40-70 ng/ml (100-175 nmol/l)
Therapeutic ( levels for treating cancers or coronary and heart diseases (under medical supervision))
70-100 ng/ml or ( 175 – 250 nmol/l)
100+ ng/ml (250+ nmol/l)
Many scientists and doctors don’t have agreed opinion for these numbers, but best of the both world is that ideally you should be on lower numbers of optimal or higher numbers of normal vitamin D levels.
Vitamin D Deficiency Symptoms
Vitamin D deficiency can cause very dangerous disorders. Lack of it, influence proper formation of bones in children, it can cause Osteoporosis, general depression and fatigue. Current studies are even discovering connections with cancers and diabetes.
Signs of vitamin D deficiency are as follows:
Rickets – It is the most frequent vitamin D deficiency symptom in children. As a result of vitamin D deficiency, the bones are weakened, the bone tissue fail to mineralize leading to soft and deformed bones.
Osteoporosis – Osteoporosis happen when the amount of minerals in bones is lower then certain threshold and your bones become more fragile and sensitive. It mostly affects women but it can also affect men.
Depression and Fatigue – According to scientists, depression is the result of the lack of vitamin D. They argue that because of urbanization, the sunlight can’t adequately reach the skin, reducing thus the 25(OH) level in the body, causing depression. It has been also discovered that a great number of people suffer from seasonal affective disorder during the winter due to insufficient exposure to direct sunlight. The parathyroid hormone is the one causing the vitamin D deficiency symptom – depression.
Hyperparathyroidism – Results from hypocalcemia, which is a blood condition with unusually low vitamin D level, resulting in hyperparathyroidism.
Obesity – Vitamin D deficiency is frequently linked to obesity, as the insufficient level of vitamin D holds back the production of hormone leptin, which regulates the fat in the body. Inadequate exposure to sunlight disrupts the normal function of the body, determining the individual to eat more than it is necessary for the body.
Osteomalacia – When rickets happen to adult person, condition is then named Osteomalacia. Also Osteomalacia is often used as a name for later stages of rickets regardless of patient age. Main cause for this condition is deficiency of vitamin D.
Chronic Backache - As we said already, vitamin D deficiency influence bone density. Lower density of bones results in weaker back support which further result in chronic back pain.
Hypertension – Vitamin D insufficiency is one of the factors that might lead to hypertension or high blood pressure.
The list is not complete and symptoms also might be cancers, chronic pain, diabetes, multiple sclerosis or heart diseases .
Vitamin D Deficiency Treatment and Prevention
Once your doctor recognize lack of vitamin D as a cause of the given symptom, treatment is then in most cases very simple… Doctor will prescribe probably vitamin D supplements and proper therapy for the given symptom. Therapy sometimes can consist only of having enough time on the sun.
On the other side preventing deficiency is easy. Half an hour daily outside with regular diet of vitamin D rich foot is enough to keep your levels on normal scale.
Recommended Vitamin D Daily Intakes
In order to avoid mentioned vitamin D deficiency symptoms you should consider to have regular daily intake of vitamin D, through food, sun or supplements. Institute of medicine (USA) and Office of dietary supplements (USA) until 2010 recommended smaller dosage of vitamin D, but back in 2010 they published new figures, which doubled previously recommended dosages.
Here is overview of recommended vitamin D daily intakes:
- infants till 12 months old (male and females) 400 IU daily
- 1 – 70 years, both males and females – 600 IU daily
- 71 and upper, both males and females – 800 IU daily
- pregnant and lactating females – 600 IU daily
Food Sources Rich in Vitamin D
There are many food types which are rich in vitamin D. Mostly, food rich in vitamin D are from animal origin. Vitamin D3 in fortified food in 99% cases also is from animal origin. Plants except some algae species are usually poor in vitamin D. Third type of good vitamin D source are mushrooms.
Here I will list some of the food sources rich with vitamin D (you can also check main vitamin D foods article for details)
- Cod liver oil and fish liver oil (cod liver oil also contain lots of vitamin A)
- Fish (all types of fish are rich with vitamin D but these bellow are richest)
- Salmon (especially Sockeye)
- Fortified milk products (Milk, Margarine, Yogurt, Cheese)
- Fortified Soy products such as soy milk or tofu
- Mushrooms (vitamin D2)
- Beef liver
- Fortified juices (mostly fortified Orange juice)
- Vitamin D supplements
Vitamin D Supplements
Most of the vitamin D supplements are produced from Lanolin. It is the substance found in sheep’s wool. Most simply said, 7-dehydrocholesterol, main ingredient of lanolin is irradiated by ultraviolet light, which results in production of compounds very potent with vitamin D3. Those compunds are further refined in order to get clean vitamin D3. Most of the vitamin D3 fortified foods, contain vitamin D3 produced from lanolin and thus are not suitable for vegans, however there are certain food and supplement producers who fortify their products with vitamin D2 produced from ergosterol which is derived from some types of yeasts and fungi’s.
In any case both types of vitamin D3 are very effective in doing their job.
Food Sources of Vitamin D for Vegetarians and Vegans
There are no many sources of vitamin D from food for vegetarians and vegans. From above list you can see that for vegetarians good sources are eggs, mushrooms, diary products, soy fortified products and vitamin D supplements. For vegans only mushrooms and supplements derived from fungi and yeasts are good choice.