Difficult it can be to get through the gray and dark winter days. How we ensure we stay happy and healthy during these lazy, indoor days; at least for those people who live in Northern climates. Vitamin D is one of the vital vitamins of which we must be aware of the intake, especially during the winter when there is not much sun, when you are spending most of your time indoors due to the cold climate you're living in or maybe due to your job, age or other health reasons... 

Make-believe summer lasts for a minute or two as kindergarten children in sunless Lovozero bathe in ultraviolet light. Brief exposure to UC radiation provides the children with vitamin D, normally supplied by sunlight. The "sunshine vitamin" strengthens young bones.

Over History humans relied on sunlight as a major source of vitamin D. Here is how:
Our body can create under influence of the UV-B part of Sunlight pre-vitamin D3 out of a compound derived from cholesterol (7-dehydrocholesterol), that is present in oil glands of our skin. In further process, this is converted to the active form of vitamin D that performs many functions in the body.

Vitamin D plays a major role in keeping blood calcium at optimal levels and it supports bone and teeth health during growth and throughout life.
Vitamin D stimulates the absorption of bone-building minerals, calcium and phosphorus from the bowel and helps regulate the amount of calcium in bone. It is important for proper functioning of cells throughout the body that depend on calcium such as nerves, muscles and glands.
Vitamin D also plays an important role in our immune system, skin, pancreas and is associated with a 17% reduction in all cancer incidences and a 29% reduction in total cancer mortality with even stronger effects for digestive-system cancers.

Vitamin D deficiency can occur for a number of reasons:

# You don't consume the recommended levels of the vitamin over time. This is likely if you follow a strict vegan or vegetarian diet; most of the natural sources are animal-based, including fish and fish oils, egg yolks, cheese, and beef liver.
# You have dark skin. The pigment melanin reduces the skin's ability to make vitamin D in response to sunlight exposure. Some studies show that older adults with darker skin are at high risk of vitamin D deficiency.
# Your kidneys cannot convert vitamin D to its active form. As people age their kidneys are less able to convert vitamin D to its active form, thus increasing their risk of vitamin D deficiency.
# Your digestive tract cannot adequately absorb vitamin D. Certain medical problems, including Crohn's disease and Celiac disease, can affect your intestine's ability to absorb vitamin D from the food you eat.
# You are obese. Vitamin D is extracted from the blood by fat cells, altering its release into the circulation. People with a body mass index of 30 or greater often have low blood levels of vitamin.

Vitamin D sources:

Getting Vitamin D from Sunlight: Anything that affects the amount of UV radiation that penetrates the skin, has a tremendous effect on the production of vitamin D in the skin and thus on vitamin D status. The production of Vitamin D3 out of sunlight is influenced by a number of factors that you should take in account:
# Angle of Sunlight; Time of day, season, and latitude all influences the amount of UV-B that reaches your skin. When the Sun's rays enter the Earth's atmosphere at too much of an angle, the atmosphere diffuses (blocks) the UV-B portion of the rays. For vitamin D production, sun exposure should be midday between the hours of approximately 10am-2pm. These hours will vary slightly according to latitude. The closer to solar noon, the more vitamin D produced.
# Skin color; the darker your skin the more exposure to sunlight is required. People with white Skin, blond/red hair will need around 15 minutes of sun exposure a day whereas those with dark skin will need longer exposure times - up to 6 times longer.
# Amount of skin exposed – at least 40% of the entire skin surface should be exposed for optimal vitamin D production. The torso produces the most, legs and arms some, hands and face very little or none at all.  
# Sunscreens; Use of sunscreen or -lotions with SPF 8, decline the vitamin D3 production by 97.5% decline.Protection factor 15 inhibits the vitamin D production by 99%.                    

Artificial UV-B
With a tanning bed, many of the vitamin D-producing UV-B rays are filtered out, because that part of the UV spectrum (which is responsible for vitamin D3 production) causes also redness, burning and skin cancer. In a sun lamp or lamps used for light therapy such filtering of UV-B radiation does not occur. Nevertheless in sun bed users are found significantly improved vitamin D levels compared with people who do not use them

Two forms dietary vitamin D:
D2 originates from plants, present in a few mushrooms, certain seaweeds and yeast. Vitamin D2 as a fortified food supplement is produced from yeast by irradiation.
D3 is from animal origin, most present in oily fish (eg eel, salmon and mackerel) and as a  fortified food supplement from fish, sheep wool, hides or cattle brains.

Often milk or margarine which may be thought of as a vegetarian product will contain D3 (animal origin) Occasionally a soy milk can be found that uses D3 instead of D2 though most have chosen the plant originated D2 form. You can check the nutrition panel of such products before choosing.

Where to buy your Vitamin D2 supplement:
@ our favorite Vegan Essentials Store, either your local Organic shop or Pharmacy.

 Be aware that Vitamin D3 (animal origin) is at least 3 and most probably 10 times stronger that Vitamin D2 (plant origin), partly because a stronger binding affinity to the vitamin D receptor. Vitamin D3 in humans is therefore preferable in case of supplementation. Although vitamin D2 is used frequently, it is now by experts not considered equivalent to vitamin D3.

Recommended Dietary Allowances (RDAs) for Vitamin D 
Age Male Female Pregnancy Lactation
0–12 months*400 IU
(10 mcg)
400 IU
(10 mcg)

1–13 years600 IU
(15 mcg)
600 IU
(15 mcg)

14–18 years600 IU
(15 mcg)
600 IU
(15 mcg)
800 IU
(20 mcg)
800 IU
(15 mcg)
19–50 years600 IU
(15 mcg)
600 IU
(15 mcg)
800 IU
(20 mcg)
800 IU
(20 mcg)
51–70 years600 IU
(15 mcg)
800 IU
(20 mcg)

>70 years800 IU
(20 mcg)
800 IU
(20 mcg)

* Adequate Intake (AI)

Deficiency of Vitamin D can lead to:

1) Rickets, misshapen of legs and other parts of body by children
2) Osteomalacia or "soft bones" the adult form of rickets.
3) Osteoporosis, brittle and porous bones due to loss of a great deal of the calcium and mineral content the   bones once had.
4) Insulin resistance and development of Diabetes Type II in Overweight children and young adults
5) Increased risk of death from cardiovascular disease.
6) Cancer
7) Severe asthma in children.
8) Depression
9) Dementia in older adults

Excess of Vitamin D can lead to:

1)Great calcium deposits in the kidneys and other body parts
NOTE: You will not get a vitamin D toxicity from too much sun, but be aware that overexposure to the sun at middays without protection may lead to sunburn and skin cancer!
If you are interested to read more, here some suggested links:




Sources I used for this article: