Natural Sources of Vitamin D

Diet is not a major source of vitamin D. Perfectly reasonably and well balanced diet may not supply the amount required to prevent deficiency.

Some food items that naturally contain small amounts of vitamin D include oil fish such as salmon, mackerel and blue fish. Cod liver oil is the best source of vitamin D.

The two basic substances with vitamin D activity D2 and D3, occur only in yeast and fish liver oils.

Vitamin D is also present in small quantities in vegetables, meat and egg yolk.

The main food source are those to which crystalline vitamin D has been added. Milk, because it is commonly used, has prove to be the most practical carrier.

The most efficient source of the vitamin is not a food at all, but exposure to sunlight, which transforms a related pro-vitamin substance in the skin into a substance which the kidney can change into active vitamin D.

Sunlight, in the form of ultraviolet-B radiation, providing 90-100% of the requirement for most people who are exposed to adequate sunlight.

Like other fat soluble vitamins, the sunlight activated pro-vitamin D can be stored away in the liver.

Vitamin D can also be obtained from nutritional supplements, For example, multivitamin supplements typically contain 400 IU vitamin D and pharmaceutical preparations can contain as much as 50,000 IU vitamin D per capsule/tablet.
Natural Sources of Vitamin D

Food sources of tocotrienols

Vitamin E is one of the major essential vitamins. Since vitamin E is an essential nutrient for protecting the bio-membrane from oxidative damage, people have to take in sufficient amounts of vitamin E to maintain and promote nutritional health.

Vitamin E consists of two subgroups called tocopherols and tocotrienols. Tocotrienols are less common and belong to the vitamin E family and are potent lipid antioxidant. In foods, in which they occur, they are generally only found in small amounts.

Tocotrienols have become a focus of research in recent years because of new findings showing their high efficacy in protecting against heart-related diseases, including lowering of cholesterol and against certain cancers.

The sources with the largest amount of tocotrienols include wheat, barley, rice and most abundantly, the fruit of the palm from which palm oil is extracted.

Palm oil is by far the richest source of tocotrienols. Palm oil is unique because it contains both tocotrienols and tocopherols unlike other vegetable oils some of which contain mainly alpha-tocopherol as the major tocopherol component.

The tumor protective effect of tocotrienols form palm oil was demonstrated by Komiyama and Yamoka (1993), Nesaretnam (1995), Guthrie (1997) and others.

The vitamin E fraction of palm oil, which is rich in tocotrienols, appears to be important in reducing certain tumors because palm oil stripped of the vitamin E does increase tumor yields.
Food sources of tocotrienols

Food sources of vitamin A

About half of dietary vitamin A intake comes from animal food sources as preformed vitamin A, the retinoids.

Preformed vitamin A is common in animal foods, especially liver and eggs. Other sources including, butter, whole milk and cream, whole milk yoghurt and fortified skim milk.

The other half of dietary vitamin A intake comes from fruits and vegetables in the form of pro-vitamin A carotenoids, especially beta-carotene. Green leafy vegetables, dark orange and red fruits and vegetables are good food sources for carotenoids.

Carotene is a precursor of vitamin A; that is the body converts carotene to vitamin A.

All-trans dehydroretinol, previously known as vitamin A2, is vitamin A related compound found in freshwater fish flesh and liver.

The definitive fast food meal – a hamburger, fries and cola – lacks of vitamin A. Many fast food restaurants, however, now offer salads with cheese and carrots and other vitamin A rich foods.
Food sources of vitamin A

Occurrence of vitamins in foods

Occurrence of vitamins in foods
In spite of the considerable and still rapidly increasingly commercial production of vitamins, the daily diet is and will long remain the major source of vitamins for human beings.

The vitamins are very unevenly distributed among the various foods however so that knowledge of the occurrence of the vitamins in the most important foods is important for provision of a balanced supply.

Meat and meat products are excellent source of thiamin, riboflavin, niacin, vitamins B6 and B12, pantothenic acid and biotin.

Liver is rich in vitamins A, D, E B12 and folic acid. Meat generally contains little vitamin K, which occurs mainly in vegetables.

An exception is pork liver, which can contain 115-230 ug/100 g. With the exception of liver and kidneys, meats contain much less folic acid than many vegetables.

Meat is generally not a good source of vitamin C.

Milk and milk products are among the most important sources of vitamins. An infant younger than one year consumes about 800 g milk daily; children and youth under 18 years of age consume 600-700 g milk daily.

Milk products supply about 40% of the required riboflavin and they are also an important source of vitamin A, B6, B12 and thiamin.

The enrichment of milk with irradiated ergosterol has practically eliminated dietary rickets in the USA.

Vitamin D occurs only in relatively small amounts in most foods. Skim milk should, as a rule, be enriched with vitamins A and D.

Cheese ahs been an important source of nutrients for thousands of years.
Occurrence of vitamins in foods

B Vitamins – Thiamin and Riboflavin

B Vitamins – Thiamin and Riboflavin
Thiamin
The B vitamins are water soluble. Thiamin – vitamin B1 is involved in all bodily oxidations that lead to the formation of carbon dioxide. It is necessary for nerve function, appetite, and normal digestion. It is also required for growth, fertility, and lactation. The symptoms of vitamin deficiency are retardation of growth, palpitation and enlargement of the heart, hypertension, and beriberi. The various effects of a disturbance of the nerve centers such as forgetfulness or difficulty in thinking are other manifestations of vitamin B1 deficiency. The vitamin is often lacking in the diet because much of the naturally occurring amounts of it in food are destroyed during the processing of the food. The adult requirement of vitamin B1 is related to the food (calorie) intake. Fresh pork is an excellent source of vitamin B1 and the heart, liver, and kidneys of pork, beef and lamb are fair sources.

Riboflavin
Riboflavin – vitamin B2 is water soluble. This vitamin makes up a part of enzyme systems involved in the oxidation and reduction of different materials in the body. Deficiency of riboflavin generally results in growth retardation and may result in vision impairment, sealing of the skin, and lesions on mucous tissue. Neuritis is another deficiency effect. The minimum intake of riboflavin for an adult is about 2.0mg per day. The liver and kidney of pork, beef, and lamb are excellent sources of riboflavin, and the heart of these animals is a good source. Fair amounts of riboflavin are found in the muscular tissues of pork, beef, and lamb, while more is found in veal.
B Vitamins – Thiamin and Riboflavin