There are four fat-soluble vitamins, A, D, E, and K. Vitamins are essential to good health and necessary for normal body processes. Optimum health is achieved when vitamin levels are sufficient to support the many biological functions of our cells. Vitamins work with enzymes in the chemical reactions that make our intricate bodies work, including production of energy. Vitamins and enzymes work in harmony, acting as catalysts that speed up the making or breaking of chemical bonds that join molecules together. Fat-soluble vitamins require bile for their absorption, and travel through the lymphatic system in chylmicrons. They enter the bloodstream and may require protein carriers for transport. Excesses of fat-soluble vitamins are stored in the liver and adipose tissues until they are needed. The fat-soluble vitamins are not often deficient because the body can store them and then go and get them when needed.

Vitamin A is an important part of the retinal group, which can be found in several forms. It was first discovered from research back in 1913, by 1917 the substance was named fat-soluble factor A. The scientists discovered at that time, that carbohydrates, fats and proteins were not the only necessary nutrients needed for cattle to thrive. It was noticed that the cattle fed a diet deficient of natural fats had reduced immune systems and their growth was not normal. They also noticed the eyes became inflamed and infected. By supplementing cod liver oil or butter fat, the cows recovered. Vitamin A was the first fat-soluble vitamin to be discovered, and in it’s purest form it is a yellow crystal that is fat-soluble.

The two forms of vitamin A are the carotenes (precursors to vitamin A) and retinal (actual vitamin A). In foods of animal origin the major form of vitamin A is retinol (an alcohol), but can also be an aldehyde (retinal) or an acid (retinoic acid). Precursors to vitamin A are present in foods of plant origin as some of the members of the carotenoid family. All forms of vitamin A have a BETA- ionone ring to which an isopreNOID chain is attached, (thus the BETA and caroteNOID names). This structure is essential for vitamin A activity. The orange pigment in carrots (beta-carotene) can be represented by two connected retinyl groups. A retinyl group being attached to a protein is the only primary light absorber in visual perception. This compounds name is related to the retina of the eye.

Carotenes represent the most widespread group of naturally occurring pigments in nature. They are an intensely colored (red and yellow) group of fat-soluble compounds. Photosynthesis, that transforms sunlight into chemical energy, is done with the help of carotenes. The carotene not only helps with photosynthesis, it also protects the plant from free radicals. There are over 600 carotenoids, 30-50 of which have vitamin A activity. Caretenoids have many functions other than vitamin A activity, such as their antioxidant effects. Beta-carotene is said to be the most active of the carotenoids because of its high vitamin A activity, however several other carotenes exert greater antioxidant effects. Beta-carotene can be split in the intestines to form retinol, which can be converted to active vitamin A by the cells. However the conversion and absorption of beta-carotene is considerably less than retinal.

Retinol is a term for vitamin A signifying that it is an alcohol involved in the function of the retina of the eye. Retinol is found in nature as long chains of molecules. Retinoic acid is the term for the acid form and retinal or retinaldehyde for the aldehyde form of vitamin A. These are the active forms of vitamin A and some believe retinol to be a precursor. Retinal is primarily involved with vision and reproduction and retinoic acid with growth and differentiation of cells. The cells can convert retinol to retinal, the active form of vitamin A.

The active form of vitamin A can be found in liver, kidney, butter, whole milk, chili peppers, dandelion root, carrots, apricots, collard greens, sweet potatoes, parsley, spinach, and broccoli to name a few. Beta-carotenes (precursors to vitamin A) can be found in green plants, carrots, squash, sweet potatoes, spinach, apricots, and green peppers, also. The carotenes in vegetables are directly related to the intensity of the color of the food. The darker green and more vibrant orange colors contain the greatest concentration of the carotenes. Legumes, seeds, and grains are also significant sources of carotinoids. Carotenoids are also found in salmon, egg yolk, shellfish, and poultry. Carotenes from supplements are better absorbed than carotenes from foods.

While vitamin A deficiencies are rare in this country, in developing countries blindness, night blindness and hyperkeratosis (a buildup of cellular debris in the skin follicles causing a goosebump like appearance) are symptomatic in a long-term lack of vitamin A. The RDA for vitamin A is measured in micrograms or retinal equivalents today. That requirement is 700-900 micrograms per day (female-male).

Vitamin A obviously has beneficial effects on our visual system. The human retina has four kinds of vitamin A. It also plays a role in growth and development, reproduction, immune enhancement, and antioxidant activity. Vitamin A plays an essential role in maintaining the epithelial and mucosal surfaces, helping to ward off unwanted intruders into the body. Retinol has demonstrated significant antiviral activity, whereas carotenes have superior antioxidant effects. Some carotenes have little or no vitamin A activity, but posses other qualities. Lycopene (in tomatoes) is low in carotene yet show significant anti-cancer effects. Vitamin A is primarily used as an immune enhancer in viral illnesses, the treatment of skin diseases, and support for the visual system. Carotenes are used as antioxidants in the prevention of cancer, as immune enhancing agents, and in the treatment of photosensitivity disorders.

Some specific applications of therapeutic doses of vitamin A and carotenes may be in the treatment of cancer, and in reducing deficiencies to aid in the treatment of measles and RSV (respiratory synctial virus) in children. Certain skin disorders, acne and psoriasis may benefit from high doses of vitamin A and beta-carotene can also prove beneficial without any fear of toxicity as with vitamin A. Topical vitamin A can help dry eyes. Beta-carotenes are believed by some to have preventative factors in the formation of cancer. High carotene intake has proved beneficial in the prevention of cardiovascular disease, and is an immune enhancing agent. Your health care provider should determine dosages.

Vitamin A supplements should not be used during pregnancy. Beta-carotene does not have the possibility of toxicity, as does vitamin A. Excess intake of beta-carotene can lead to a yellowing of the skin, which is not a problem. Generally toxicity of vitamin A only occurs with high dose therapeutic applications over several years. Toxicity does not occur from food sources.


Vitamin D is considered a vitamin and a hormone. Its unique ability to be produced by sunlight on the body makes experts consider it a hormone. Vitamin D is actually a prohormone with no hormone activity itself, however it is converted to a hormone. When the sunlight hits our body a precursor of vitamin D in our skin, made in the liver from cholesterol reacts with the sunlight making previtamin D3 an inactive form of vitamin D. Then in the kidneys and liver it is slowly converted to active vitamin D3. It is again with the help of enzymes these transformations take place. Vitamin D has two forms, D2 (ergocalciferol) and D3 (cholecalciferol). Contrary to popular belief the sun is not our enemy. This planet thrives on three components for survival, the air, the water, and the sun. While overexposure to the sun can cause aging and wrinkles, and in undernourished people may contribute to skin cancer, it is an important source of vitamin D. Our bodies were designed to use the sun to make this vitamin so it seems unnatural to go to the great lengths people do to avoid any contact with the sun.
Vitamin D can also be found in cod liver oil, cold-water fish, butter, and egg yolks. It is found in green leafy vegetables but not in high quantities.

Vitamin D deficiency is the cause of rickets in children and osteomalacia in adults. The lack of vitamin D directly affects the stability of the bones. Fortified milk has made these diseases rare today. Vitamin D has an Adequate Intake allowance of 10 micrograms per day assuming you get no sunlight. Vitamin D is more often recommended in IU’s, which would be 400 per day (male or female).

Like vitamin A, vitamin D requires a binding protein to transport it to its target organs, most notable the bones, kidneys, and intestines. Vitamin D stimulates the absorption of calcium in the bones, and its special role in bone growth is to maintain proper calcium and phosphorus levels in the blood. There are different forms of vitamin D that all have different effects on calcium metabolism. Vitamin D along with vitamins A, C, and K, work together in bone making and maintenance, along with a wide variety of other nutrients.  Disorders of the kidney and liver may lead to vitamin D deficiency related diseases such as osteoporosis, where the conversion of vitamin D is not complete. Vitamin D also targets the cells of the immune system, the brain and nervous systems, pancreas, skin, muscles and cartilage, and reproductive organs. Vitamin D also shows anticancer properties especially in the areas of breast and colon cancers. Vitamin D has also shown to play a role in preventing or reversing coronary disease.

Vitamin D has the greatest potential of all the vitamins to be toxic. An increase of calcium may be deposited in internal organs (i.e. kidney stones) as a result of too much vitamin D. Also long term over-consumption of vitamin D in fortified foods contributes to atherosclerosis and heart disease. Please check with your health care provider for specific dosing of any fat-soluble vitamin.


Vitamin E was discovered in 1922. It was found that rats given a diet without vitamin E were no longer able to reproduce. Once wheat germ was added they again began to produce baby rats. Thus vitamin E became known as the “anti-sterility” vitamin. Alpha-tocopherol is the most active form of vitamin E, and the word tocopherol comes from the Greek word tokos meaning “offspring” and phero meaning “to bear”. Thus tocopherol literally means, “to bear offspring”.

The need for vitamin E increases with the amount of polyunsaturated fats a person consumes. Fortunately in nature the more polyunsaturated foods contain more vitamin E. The best sources of vitamin E are polyunsaturated vegetable oils, nuts, seeds, and whole grains. Also vitamin E is found in avocados, asparagus, berries, green leafy vegetables, corn, olives, and tomatoes. Food processing and cooking of foods does reduce vitamin E content. While the most common form of vitamin E is alpha-tocopherol, there are many other tocopherols that have been less studied but may show therapeutic results. A vitamin E supplement with mixed tocopherols would be advantageous. There are water-soluble forms of vitamin E however they are very expensive and do not prove any more effective for normal dietary supplementation.

Vitamin E functions primarily as an antioxidant in protecting cell membranes from damage. Without vitamin E the nerve cells would be at risk for damage. Vitamin E deficiency is very rare, however there are conditions where low levels of vitamin E prove detrimental, such as celiac disease, cystic fibrosis, sickle cell anemia, and in premature infants to name a few. The RDA for vitamin E is 12-15 IUs (females-males).

Vitamin E is actually incorporated into the lipid (fatty) portion of the cell membranes where it acts to stabilize and protect against heavy metals, cleaning solvents, drugs, and radiation. Vitamin E enhances the immune system and particularly protective during times of the stress of viral attacks.

Vitamin E has an impressive list of health conditions that it may benefit. Most common are its effects against heart disease, cancer, and stroke. Vitamin E provides significant antioxidant benefits against heart disease and stroke by reducing LDL levels (bad cholesterol), inhibiting excessive platelet aggregation, and raising the HDL (good cholesterol). Other antioxidant protection is significant in the prevention of cancer when vitamin E is taken in high doses. Vitamin E supplementation can help in preventing long-term complications in diabetes. Fibrocystic breast disease, menopausal symptoms and Tardive Dyskinesia are also benefited with high doses of vitamin E. Your health practitioner should help you decide any doses needed.


Vitamin K is a little known vitamin. It is probably most famous for interfering with blood clotting drugs. These drugs work to stop blood clots and vitamin Ks mission is to clot the blood. Vitamin K was discovered in 1929 while investigating the effects of reduced cholesterol on chickens. The chickens eventually hemorrhaged and the “koagulationvitamin” was discovered. The German spelling gave it its “K”. Vitamin K is also necessary for building healthy bones, and in the prevention and treatment of osteoporosis. Vitamin K comes from plant sources and is also derived from the bacteria in the gut. Babies, being born with a sterile digestive system, are given a single dose of vitamin K at birth to prevent hemorrhagic disease as they have not yet developed the vitamin K. Vitamin K deficiencies are rare since it is manufactured by the bacteria in the gut. The RDA for vitamin K is 90-120 micrograms per day (female-male).

There are three major forms of vitamin K, vitamin K1 (phylloquinone), the natural vitamin K from plants, K2 (menaquinone) derived from the bacteria in the gut, and K3 (menadione) a synthetic version. Good sources of plant vitamin K are dark green leafy vegetables, broccoli, lettuce, cabbage, spinach, and green tea. Vitamin K is also present in asparagus, whole wheat, oats, and fresh green peas. Chlorophyll in plants is fat-soluble and the best source of vitamin K, however the chlorophyll in health food stores is water-soluble and may not provide the same benefits. I think as you see from all the fat-soluble vitamins, vegetables, vegetables, and dark leafy green vegetables are your friends.

Vitamin K and fat-soluble chlorophyll are used in the prevention and treatment of osteoporosis, excessive menstrual bleeding, and Hemorrhagic Disease in newborns. It can also fight tooth decay naturally as it inhibits the enzymes that help to form the acids that breakdown tooth enamel. Vitamin K taken with Vitamin C is a very effective, but little known treatment of nausea and vomiting in pregnancy.

While vitamin K has no known side effects or toxicity, it can interfere with anticoagulant drugs and should not be consumed when on those.

I believe that disease prevention starts with a balanced diet of organic vegetables, fruits, grains, legumes, nuts, seeds, protein, fats, and carbohydrates. Along with exercise and a low stress lifestyle a person does not have to suffer all the degenerative diseases so common today. Knowledge is your best defense and the best promise of a healthy life.

Submitted by Tricia @ Nutrition by Tricia

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