How does VITAMIN D work in the body? why are many people deficient? and which supplement is recommended to take?
Vitamin D is a fat-soluble pro-hormone.
It is obtained either through the action of sunlight on the skin or from dietary sources. (1)
Vitamin D helps regulate the amount of calcium and phosphate in the body.
(These are needed to keep bones, teeth and muscles healthy).
A lack of vitamin D can lead to bone deformities such as rickets in children, and bone pain caused by a condition called osteomalacia in adults. (2)
Vitamin D has other roles in the body, including modulation of cell growth, neuromuscular and immune function, and reduction of inflammation. (3)
Vitamin D is a unique vitamin because it can be made in the skin from exposure to sunlight.
VITAMIN D & SUN
NATUROPATHIC RECOMMENDATION: IT IS RECOMMENDED TO WALK OUTSIDE AND ABSORB SUNLIGHT EVERY DAY OF ABOUT 20 MINUTES, AVOIDING THE TIME WHEN THE SUN IS THE STRONGEST.
Daily walks inspiration
In the UK during autumn and winter (from October until the end of March) the sun is not strong enough to produce vitamin D.
Unfortunately, most of us cannot get enough just from the diet.
There is a risk of not getting enough vitamin D.
Taking a supplement helps to keep levels of the vitamin covered during the colder months.
During the summer months, we usually use a high factor sunscreen meaning the UVB rays do not reach or enter the skin.
People with dark skin colour required more exposure to sunlight in order to stimulate vitamin D production, this is because of the melanin pigment which prevents the UV light from penetrating far enough into the skin for vitamin D synthesis.
FORMS OF VITAMIN D – D2 & D3
Vitamin D2 is obtained from the UV irradiation of the yeast sterol (ergosterol) and is found naturally in sun-exposed mushrooms.
Since vitamin D2 is cheaper to produce, it’s the most common form in fortified foods.
vitamin D3 by humans when UVB light from the sun strikes the skin.
Human beings do not make vitamin D2, and most oil-rich fish such as salmon, mackerel, and herring contain vitamin D3.
A study of the bioavailability of vitamin D2 in mushrooms compared with the bioavailability of vitamin D2 or vitamin D3 in a supplement
revealed that ingestion of 2000 IUs of vitamin D2 in mushrooms is as effective as ingesting 2000 IUs of vitamin D2 or vitamin D3 in a supplement in raising and maintaining blood levels of 25-hydroxyvitamin D which is a marker for a person’s vitamin D status. (6)
In the body-
Vitamin D that comes from the skin or diet is biologically inert and requires transformations in the liver and kidneys to form the biologically active form of vitamin D.
Without vitamin D, only 10–15% of dietary calcium and about 60% of phosphorus are absorbed.
Vitamin D sufficiency enhances calcium and phosphorus absorption by 30–40% and 80%, respectively. (4)
SYMPTOMS OF DEFICIENCY INCLUDES
- Lack of energy and fatigue
- Poor immune system
- Muscle aches
Very few foods in nature contain vitamin D
Vitamin D in these foods is primarily in the form of vitamin D3:
- Fatty fish (such as salmon, tuna, and mackerel) and fish liver oils are among the best sources.
- Small amounts of vitamin D are found in beef liver, cheese, and egg yolks.
Some mushrooms provide vitamin D2 in variable amounts.
Mushrooms with enhanced levels of vitamin D2
from being exposed to ultraviolet light under controlled conditions. (3)
Fortified foods represent today the major dietary sources of vitamin D, as very few foods naturally contain significant amounts of vitamin D.
Obtaining sufficient vitamin D from natural food sources alone is difficult.
THE RECOMMENDED FORM OF SUPPLEMENT IS VITAMIN D3, IN LIQUID FORM.
THE AMOUNT THAT IS NEEDED IS VARIED ACCORDING TO EACH PERSON.
According to the NHS, If you choose to take vitamin D supplements, 10mcg / 400 IU a day will be enough for most people for maintenance.
Too much vitamin D-
Taking too much vitamin D supplement over a long period of time can cause too much calcium to build up in the body (hypercalcaemia). This can weaken the bones and damage the kidneys and the heart.
- Adults, including pregnant and breastfeeding women and the elderly, and children aged 11-17 years- Don’t take more than 100mcg/ 4000 IU of vitamin D a day as it could be harmful.
- Children aged 1-10 years shouldn’t have more than 50mcg / 2000 IU a day.
- Infants under 12 months shouldn’t have more than 25mcg / 1000 IU a day.
Some people have medical conditions that mean they may not be able to safely take as much. If in doubt, you should consult your doctor.
If your doctor has recommended you take a different amount of vitamin D, you should follow their advice. (5)