However, if the body does not make enough, it can be found from food sources in tiny amounts. In fact, many countries add it automatically to certain foods like milk. Supplements can be easily found in most developed countries.
Vitamin D is a fat-soluble nutrient. This means that any portion not used immediately is stored in fat tissue for future use.
As a hormone, Vitamin D does many things in the body. It was first discovered as the substance which could prevent and cure rickets. It controls the levels of calcium ions and phosphates in the blood, as well as calcium and magnesium absorption in the intestines. It helps bones grow and form. It is also good for the immune system.
In total, there are 5 different forms, D to D. The most common ones are D and D (see images).
D (also called cholecalciferol) is the kind produced by the body. It is also found naturally in marine oils and in lanolin (oil from sheep's wool), the most common source for supplements.
D (also called ergocalciferol) is produced by fungi. It is similar to D, but not exactly the same.
D is made in the skin from cholesterol, and changed into a more active form by the liver. However, the skin will not make it unless enough ultraviolet light shines on it. As sunlight contains ultraviolet light, getting enough sun is one way of getting enough D.
Many things can keep the skin from making enough D. Winter sunlight may be too weak. Melanin, which protects skin from damage, also keeps it from making D, which is why people with darker skin are more prone to deficiency. Older people are also prone, because aging skin makes less D, even with enough sunlight. Clothing, glass, sunscreens and sunblocks also shield the skin from getting enough ultraviolet light to make D.
It is hard to know how much supplemental Vitamin D, if any, is needed. Less than 25 micrograms (1000 IU) per day, but up to 100 mcg (4000 IU) per day is considered safe. A recent panel of Vitamin D researchers concluded that "at least" 20-25 mcg (800-1000 IU) per day would help most adults.
Few foods naturally contain much D. Fish do, especially oily ones, such as salmon, sardine and mackerel. Many kinds of edible mushrooms contain some D, like shiitake. Mushrooms grown in full sunlight tend to have more.
Biome
In ecology, a biome is a major regional group of distinctive plant and animal
communities best adapted to the region's physical natural environment,
latitude, elevation, and terrain.
A biome is made up of ecoregions or settlements at stable steady state and all associated transitional, disturbed, or degraded, vegetation, fauna and soils, but can often be identified by the climax vegetation type.
The biodiversity characteristic of each biome, especially the diversity of fauna and subdominant plant forms, is a function of abiotic factors and the biomass productivity of the dominant vegetation. Terrestrial biomes with higher net primary productivity, moisture availability, and temperature.
A fundamental classification of biomes is into:
Biomes are often given local names. For example, a temperate grassland or shrubland biome is known commonly as "steppe" in central Asia, "savanna" or veld in southern Africa, "prairie" in North America, "pampa" in South America and "outback" or "scrub" in Australia.
Sometimes an entire biome may be targeted for protection, especially under an individual nation's "Biodiversity Action Plan".
Climate is a major factor determining the distribution of terrestrial biomes. Among the important climatic factors are:
Biodiversity generally increases away from the poles towards the equator, and increases with humidity.
The most widely used systems of classifying biomes correspond to latitude (or temperature zoning) and humidity.
In 1975, Miklos Udvardy published a system of biogeographic provinces that were divided into 12 terrestrial biomes.
Robert G. Bailey developed a biogeographical classification system for the United States in a map published in 1975. Bailey subsequently expanded the system to include the rest of North America in 1981, and the world in 1989. The Bailey system is based on climate, and is divided into four domains (Polar, Humid Temperate, Dry, and Humid Tropical), with further divisions based on other climate characteristics (subarctic, warm temperate, hot temperate, and subtropical, marine and continental, lowland and mountain).
A team of biologists developed an ecological land classification system for the World Wide Fund for Nature (WWF) that identified 14 biomes, called major habitat types, and further divided the world's land area into 867 terrestrial ecoregions. This classification is used to define the Global 200 list of ecoregions identified by the (WWF) as priorities for conservation. The WWF major habitat types are as follows:
The Endolithic biome, consisting entirely of microscopic life in rock pores and cracks, kilometers beneath the surface, has only recently been discovered and does not fit well into most classification schemes.
Vitamin E
Vitamin E (which is also called Tocopherol or Tocotrienol, E307, E308,E309) is a vitamin. There are eight forms of it, E to E. It can be found in vegetable oils. Very often it is also added to lotions and creams for the skin. It is supposed to help the healing of the skin, after burns and injuries, and lower the risk of heart disease and cancer.
Some research suggests that vitamin E has anti-aging benefits.
Vitamin K
Vitamin K is a vitamin which is soluble in fat. It is probably best known for its role in the coagulation (clotting) of blood. However, it also serves other important functions in the body.
Vitamin K was discovered by a Danish chemist named Henrik Dam. He won the 1943 Nobel Prize in Physiology or Medicine for discovering its key role in the coagulation of blood. Since that time, Vitamin K's role in other physiologic functions has become known. One of the most important is its role in controlling where calcium goes in the body.
Without Vitamin K, there would be a loss of blood when a person bleeds, which can lead to unconsciousness or even death. Vitamin K can be found in green vegetables, such as spinach, lettuce, broccoli or cabbage.
B vitamins
The B vitamin complex (also called B vitamins) are a group of 8 vitamins. They have an important job in the metabolism of cells. Each B vitamin is a cofactor (a coenzyme) for some key metabolic processes or it is a precursor needed to make one.
Originally, people thought they were just different forms of one vitamin (as with Vitamin D, for example). Later it turned out that they are separate vitamins that often can be found together. They are Vitamin B1/Thiamine, Vitamin B2/Riboflavin, Vitamin B3/Vitamin P/Vitamin PP/Niacin,Vitamin B5/Pantothenic acid, Vitamin B6, Vitamin B7/Vitamin H/Biotin, Vitamin B9/Vitamin M/Vitamin B-c/Folic acid and Vitamin B12. They are required for growth, and proper functioning of nerves and muscles. B vitamins are found in meat, milk, whole grains and fresh vegetables.
Vitamin B deficiencies have been shown to cause the following symptoms:
Well-known medical syndromes caused by thiamine deficiency are beri-beri, Wernicke–Korsakoff syndrome (WKS), and optic neuropathy.
Subarctic climate
Places with a subarctic climate (also called boreal climate) have long, usually very cold winters, and short, warm summers. It is found on large landmasses, away from oceans, usually at latitudes from 50° to 70°N. Because there are no large landmasses at such latitudes in the Southern Hemisphere, it is only found at high "altitudes "(heights) in the Andes and the mountains of Australia and New Zealand's South Island. These climates are in groups "Dfc", "Dwc", "Dfd" and "Dwd" in the Köppen climate classification