The Science Behind HealthWith Doctor Bones (Don R. Mueller,

Ph.D.)The Funny Man of HealthEducator

Entertainer

JU

G G LE

R

FOOD

Scientist

A Science-Based Examination of the Fat-soluble Vitamins ( A, D, E and

K)

Vitamins are essential organic compounds, needed in small amounts for normal functioning of the human body's metabolism, growth and reproduction. A vitamin is called "essential" because either we cannot make it in the body (called synthesis) or that we produce too little of it for good health.

For example, humans cannot synthesize vitamin C. Therefore, we must obtain it via our diet. On the other hand, we can synthesize enough vitamin D in our skin if we receive sufficient exposure to sunlight. If we are sun deficient, then we may also find ourselves vitamin D deficient and must obtain vitamin D through our diet.

The 13 or so vitamins that we require all play important roles in sustaining life. The fat-soluble vitamins that we need include vitamins A, D, E and K. Fat-soluble vitamins dissolve in fat and therefore can be stored in the fatty tissues of the body. As a consequence, we do not need to ingest fat-soluble vitamins daily.

An assortment of B-vitamins and vitamin C are the water-soluble vitamins that we require. Water-soluble vitamins dissolve in water and not in fat and therefore cannot be stored in the fatty tissues of the body. In order to avoid a deficiency, water-soluble vitamins are needed on nearly a daily basis.

Did you know that the word vitamin comes from the word "vitamine?" It's true! Vitamine, which means "vital amine," was coined in 1911 by the Polish-American biochemist Casimir Funk because it was thought at the time that these substances contained amines, compounds that have nitrogen (N) as part of their molecular structure.

The letter "e" in vitamine was later dropped when it was determined that not all vitamins contained nitrogen. It was Casimir Funk who discovered vitamin B1 (thiamine).

DID YOU KNOW

Fat-soluble Vitamins ( A, D, E and K)

Vitamin A (also called retinol) is fat-soluble, and as such, can be found in the body’s fatty tissues, although the majority is stored in the liver as retinyl palmitate. Vitamin A can be obtained either directly from foods that are substantial in vitamin A (e.g., beef liver, fish liver oils, egg yolks and butter) or by converting a substance called beta-carotene into vitamin A.

In 1913, the biochemist Elmer V. McCollum and his colleagues conducted nutritional studies that led to the discovery of vitamin A in butterfat and cod liver oil. McCollum originally called it "fat-soluble factor A" and then later "vitamine A."

An early sign of vitamin A deficiency is night blindness. You've probably heard the saying, “Carrots for good eyesight!" In truth, carrots contain a substance called "beta-carotene" (carotene, coming from carrots) which the body can convert to vitamin A when needed.

"Eat your carrots!”

Beta-carotene originates from compounds called "carotenoids." These substances exhibit characteristic yellow and orange colors. In addition to its role as a provitamin for vitamin A, beta-carotene also functions as an important antioxidant compound, protecting cells from the harmful effects of free radicals.

Vitamin A has many Important Functions:

Plays an important role in vision, especially night vision.

Helps regulate cell development.

Promotes the proper growth of bones and teeth.

Boosts the body's immune system helping to increase our resistance to infectious diseases.

Vital in the formation and maintenance of healthy hair, skin and mucous membranes.

Vitamin A holds an important place in sexual reproduction.

Vitamin D - "The Sun Vitamin"

Vitamin D3 is synthesized in the body when ultraviolet light (mostly UV-B radiation) strikes our skin. Fair-skinned people need 20 to 30 minutes a day in bright sunlight to meet their vitamin D needs. The darker your skin the longer you need to be in the sun in order to make enough vitamin D.

Overcast skies, smog, clothing and sunscreens all decrease your exposure to UV-B radiation and hence decrease the amount vitamin D you can produce from sunlight. Fortunately, we can also meet our vitamin D needs with vitamin D fortified foods (milk, for example is one such item) and vitamin D supplements.

For humans, the two most important forms of vitamin D are vitamin D2 and vitamin D3. Vitamin D2 (ergocalciferol) is derived

from plants and irradiated yeast and fungi. Vitamin D3 (cholecalciferol) as discussed previously, is synthesized in the body when we are exposed to sunlight and can be obtained from foods such as milk, fortified cereals, tuna, salmon and fish oils.

Vitamin D2 and vitamin D3 have equal biological activity. Both can be converted, first to calcifediol (a transport form of vitamin D) in the liver and then to the bioactive form of vitamin D, calcitriol (1,25-dihydroxycholecalciferol) in the kidneys. Calcitriol is then transported via a carrier protein to the various sites in the body where it is needed.

Some of the many useful functions of Vitamin D Vitamin D aids in the absorption of calcium and phosphorus from the small intestine for the normal mineralization of bone.

Vitamin D helps regulate calcium levels in the blood, ensuring that nerves and muscles function properly, as calcium is vital for nerve cell transmissions and muscle fiber contractions.

There is evidence that vitamin D (specifically, vitamin D3) is involved in regulation of the body's immune system.

Vitamin D is essential for normal insulin secretion by the pancreas and therefore control of blood sugar levels.

The bioactive form of vitamin D3, (calcitriol) is believed to play an important role in the regulation of the genes involved in cell growth, differentiation and proliferation.

Vitamin E - The Antioxidant VitaminThe fat-soluble Vitamin E, is actually a family of eight different vitamin E molecules. Four of the eight vitamin E molecules are called the tocopherols (alpha, beta, gamma and delta).

Foods containing significant amounts of tocopherols include a number of oils (corn, safflower, soybean, cottonseed and canola), nuts (almonds, hazelnuts, and walnuts), wheat germ and vegetables like spinach, kale, sweet potatoes and yams.

The remaining four Vitamin E molecules are known as tocotrienols (alpha, beta, gamma and delta). Sources of tocotrienols include: oils from palm, rice bran and annatto beans.

In foods, alpha-tocopherol is in the form of d-alpha-tocopherol (the vitamin E isomer preferred by the body), which is found in a number of oils, including safflower and sunflower. It is also found in wheat germ. “Trienol” refers to three C=C double bonds.

C=C double bonds

Some of the Important Functions of Vitamin E

Vitamin E in the form of d-alpha-tocopherol is an important fat-soluble antioxidant, scavenging oxygen free radicals: lipid peroxy radicals and singlet oxygen molecules before these various radicals can do further harm to cells.

Vitamin E helps maintain the structural integrity of cell membranes throughout the body.

The isomer, d-alpha-tocopherol has been shown to inhibit the aggregation or "clumping" of blood platelets, hence, helping to reduce the risk of heart attack and stroke.

Studies show that d-alpha-tocopherol protects the fat component in low-density lipoproteins (LDLs) from oxidation and exhibits moderate cholesterol-lowering capabilities.

Vitamin K - The Anti-Hemorrhagic Vitamin

Vitamin K, was first isolated in 1939 by the Danish biochemist Henrik Carl Peter Dam, later winning the Nobel Prize in Medicine in 1943, for his work involving vitamin K.

A decade earlier, it was shown that this fat-soluble substance (present in green leafy vegetables) was required for normal coagulation of the blood.

The "K" comes from the German word "koagulation.” Vitamin K is essential for the functioning of several proteins involved in normal blood clotting. Vitamin K is needed to make four blood coagulation factors, including: prothrombin (factor II), proconvertin (factor VII), Christmas factor (factor IX) and the Stuart-Power factor (factor X).

Vitamin K1 is the major dietary source of vitamin K and is found in green leafy vegetables like lettuce, kale, parsley, spinach and various greens (turnip, beet and mustard). Broccoli is also a good source of vitamin K1 as are certain vegetable oils (soybean, cottonseed, canola, and olive).

Vitamin K1 (phylloquinone)

There are three basic forms of vitamin K, namely:

Vitamin K2, which is the most biologically active form of vitamin K, is found in egg yolks, butter, liver, cheddar cheese and yogurt. Vitamin K2 is also produced by certain "friendly" intestinal bacteria in humans and it has been suggested that products yogurt, kefir and acidophilus milk (fermented milk) may help to increase the functioning of these useful bacteria.

Vitamin K2 (menaquinone)

Important Functions for Vitamin K

The primary role for Vitamin K in human health is in the regulation of normal blood clotting.

Vitamin K has been shown to improve bone health, particularly for those at risk for osteoporosis.

Used to reduce the hazard of bleeding in liver disease.

Vitamin K3 or "menadione" is a fat-soluble synthetic (man-made) vitamin K compound, used mainly in animal feed and pet foods. Although vitamin K3 is converted to vitamin K2 in the body, it is generally not recommended for use in humans. Vitamin K3