Vitamins Are An Essential Part Of A Healthy Diet
Vitamins are organic substances functioning to facilitate an essential biochemical reaction necessary for growth, vitality and the normal functioning of our bodies. We must obtain them from our diet or take them in the form of dietary supplements, that are usually derived from plant and animal products. Crucial to the definition of a vitamin is that lack of it produces a specific deficiency syndrome, and supplying it cures that deficiency.
It is almost impossible to sustain a healthy way of life by taking only synthetic supplements and not following a good eating plan. Supplements should be taken only with some nutrition knowledge or the guidance of a nutritionist and dietitian. Many vitamins and minerals can be toxic if taken in excess. Often there are sufficient vitamins in your diet, thus by taking supplements toxicity may occur. Symptoms include hair loss, blurred vision, bone pain, fatigue and headaches.
The best way of obtaining a healthy balance of vitamins is by eating a large variety of different foods. One should try not to limit their diet to a few delicacies. Try out new dishes, be adventurous.
Fat-Soluble Vitamins. The fat-soluble vitamins are vitamins A, D, E, and K. These vitamins are absorbed, transported, metabolized and stored along with fat. The fat soluble vitamins function as regulators for specific metabolic activity.
Water-soluble Vitamins. The water-soluble vitamins include vitamin C, and those of the B-complex group: biotin, folate, niacin, pantothenic acid, riboflavin, thiamin, vitamin B6, and vitamin B12. They function mainly as coenzymes.
No data have yet been published to demonstrate that healthy people eating a well balanced diet need any vitamin supplements. A well balanced diet means that what one has eaten during the day should include a wide variety of foods from each of the five food groups (fruit, vegetables, bread and grains, meat and milk).
Except in pregnancy, where supplementation of certain vitamins may be recommended, there are no reports of normal persons eating a well balanced diet developing vitamin deficiency diseases. The proper role of vitamin supplementation is in the treatment of deficiency in patients who have inadequate intake, disturbed absorption, or increased requirements because of an increased destruction or excretion.
Mega-dose therapy is the treatment with daily quantities of a vitamin or vitamins substantially above the Recommended Dietary Allowances (RDA) of the Food and Nutrition Board. The RDAs are the levels of intake of essential nutrients considered to be adequate to meet the known nutritional needs of all healthy persons.
Vitamins, like many other substances, may be toxic when taken in large quantities. Large doses of nicotinic acid frequently cause flushing and itching, liver damage, dermatoses, elevations of serum glucose concentration and peptic ulceration may occur. Prolonged excessive intake of vitamin D can cause anorexia, nausea, weakness, weight loss, hypertension, anemia, hypercalcemia, irreversible renal failure, and death. Vitamin E in large doses antagonises the action of vitamin A and also causes headaches, nausea, fatigue, blurred vision, inflammation of the mouth, chapping of the lips, gastrointestinal disturbances, muscle weakness, low blood sugar, increased bleeding tendency, and degenerative changes.
The comments that vitamin doses in excess of the RDA may produce "optimal" health are pure speculation, unsupported by any facts in human metabolism, and contradicted by the toxicity of vitamin and mineral doses in excess of the RDA. "More is better" is a slogan, not science. More is sometimes better, sometimes worse, but always costlier.
Vitamin A (Retinol, Carotene)
Vitamin A is fat soluble, it is an antioxidant and occurs in two forms - retinol and carotene. The RDA [
Food and Nutrition Board, National Academy of Sciences - National Research Council - Recommended Dietaty Allowances. ] for adults is 1000 micrograms RE (Retinol Equivalents. 1 RE = 1 microgram retinol or 6 micrograms ?-carotene).
The allowances, expressed as average daily intakes over time, are intended to provide for individual variations among most normal persons as they live in the United States under usual environment stresses. The RDA's given are the higher of adult males or females, for more precise data refer to the RDA tables.
Because vitamin A and carotene exist in more than one chemical form, and because they are not equally active, it is usual to give the name retinol to the pure vitamin A. Thus the total vitamin A activity of a food, its retinol equivalent, is determined by how much it contains of retinol, chemicals very similar to retinol but not as active, and a range of carotenes also of varying activity.
Vitamin A maintains the skin and mucous membranes. Promotes growth, strong bones, healthy skin, hair, teeth and gums. Builds up resistance to respiratory infections and shortens the duration of diseases. It counteracts night blindness and aids in the treatment of many eye disorders. Night blindness is an early symptom of a deficiency of vitamin A.
In a dozen case-control and cohort studies, intakes of fruits and vegetables containing carotenoids has been associated with a reduced risk of lung cancer. In contrast little relationship has been found between intake of preformed vitamin A (retinol) and this disease.
Available data thus strongly support the hypothesis that dietary
carotenoids reduce the risk of lung cancer, but the data also are
compatible with the possibility that some other factor in these foods
is responsible for the lower risk. The recommendation to eat a variety
of fruits and vegetables is reasonable, but leaves much to chance; if
?-carotene is the anticancer agent, intake of specific fruits and
vegetables should be advised. [
Willett, W.C., Vitamin A and lung cancer , Nutrition Reviews, 48:201, 1990]
The best natural sources are green leafy vegetable tops, carrots, red peppers, sweet potatoes, yellow fruits, apricots, fish-liver oil and eggs.
Vitamin A is one of the few vitamins in which excess produces definite and severe effects. Toxic symptoms can occur with intake exceeding 100 000 IU's daily. Hypervitaminosis A leads to loss of appetite, a dry, itchy skin often with peeling, intense headaches and an enlarged liver. Recovery is fairly rapid when intake is reduced.
Vitamin B1 (Thiamine)
Vitamin B1 is water soluble like all the B vitamins. It is easily lost and must be replaced daily. The RDA for adults is 1.5 milligrams.
Thiamine prevents and cures beriberi, a disease of the nervous system. It aids growth, maintains normal carbohydrate metabolism and nervous system functioning. It helps alleviate stress conditions, anxiety and trauma.
The best natural sources are dried yeast, spirulina, whole wheat, oats, peanuts, soybeans, green vegetables and milk.
This vitamin is not toxic, it is easily excreted from the body and not stored. It is destroyed by heat, caffeine, alcohol and cigarette smoke.
Vitamin B2 (Riboflavin)
Vitamin B2 is not stored and must be replaced daily. The RDA for adults is 1.7 milligrams.
Essential for normal cell growth, helps to metabolize carbohydrates, fats and proteins. Benefits vision and eye fatigue, promotes healthy skin, nails and hair. Eliminates sores in mouth, on lips and tongue.
The best natural sources are milk, yeast, cheese, sea vegetables, leafy green vegetables, mushrooms, fish and eggs.
There are no known toxic effects. It is destroyed by light, alcohol and sulfur drugs.
Vitamin B3 (Niacin, Nicotinic Acid)
Niacin is a component of an enzyme and can be produced by the body, some of the amino acid tryptophane is converted into niacin. The RDA for adults is 19 milligrams.
It is necessary for a wide variety of body processes, reduces high blood pressure, lowers cholesterol levels and prevents pellagra. Without niacin, thiamine and riboflavin cannot function properly.
The best natural sources are lean meat, whole wheat, tuna, anchovy, yeast, eggs, peanuts and avocados.
Niacin is not toxic but people with peptic ulcers or diabetes should consult a doctor before taking supplements greater than 100 milligrams.
Vitamin B5 (Pantothenic Acid)
Vitamin B5 is known in other forms - Calcium Pantothenate and Panthenol. The RDA for adults is 7 milligrams.
It is necessary for the utilization of other nutrients and maintaining normal growth and development of the nervous system, as well as for the metabolism of fat and sugars.
The best natural sources are fish, whole grains, wheat germ, green vegetables and brewers yeast.
There are few known toxic effects, but very large doses have been known to produce lack of co-ordination in movement and impairment of sensation. It is destroyed by heat, caffeine and alcohol.
Vitamin B6 (Pyridoxine)
B6 has three metabolic forms pyridoxine, pyridoxal and pyridoxamine. The RDA for adults is 2.0 milligrams.
It is essential in amino acid metabolism, is required for the absorption of B12 and for the production of antibodies and red blood cells.
The best natural sources are bananas, brewer's yeast, wheat germ, green and red peppers, nuts, molasses and eggs.
Intake should be increased with diets high in protein. Daily doses of over 500 mg should be avoided. Doses over 2 g can lead to neurological disorders. Food processing techniques, canning and alcohol can deplete vitamin B6.
Vitamin B12 (Cyancobalimin, Cobalamin)
B12 contains mineral elements - cobalt. The RDA for adults is 2.0 micrograms.
The best natural sources are clams, oysters, beef, eggs and dairy products.
It is not found in many plant products except certain soya products, tempeh and sea vegetables. If you are a strict vegetarian you will need to take B12 supplements. Although, people who have diets high in protein need more B12. A deficiency can cause pernicious anemia.
B12 is not easily absorbed and needs to be combined with calcium for proper absorption. It is destroyed by sunlight, alcohol and sleeping pills. There have been no reports of B12 toxicity.
Vitamin B15 (Pangamic Acid, Pangamate, Calcium Pangamate)
Pangamic acid has not had much research done on it in the USA, but has been approved in Russia and used by athletes to enhance performance. Pangamic acid is a label not a product. The pills contain anything the seller chooses to put in them.
The Food and Drug Administration contend that "B15" is essentially an untested food additive which is not generally recognized by the scientific experts as safe for human consumption. Pangamate was prohibited within Canada for almost two decades. Because of these facts, any physician who prescribes it should first get informed consent from his or her patients after informing them that it is not a vitamin, has no known nutrient value, no known value in the long-term treatment of any disease, that its safety has not been established, and that it may be mutagenic (cancer causing).
The allegations that pangamic acid is an antioxidant, protects against pollutants, increases the life span of cells, relieves symptoms of asthma and lowers blood cholesterol levels, as well as that it stops the craving for alcohol and protects the liver from cirrhosis are anecdotal and testimonial stories rather than studies.
The authors often claim spectacular results from "pangamic acid"
without identifying which of the many chemicals and chemical
combinations which go by that name they are using. Without
distinguishing drug effect from the placebo, and without reporting any
evaluation of patients for short-term or long-term toxic effects. [
Herbert, J., (Chief Hematology & Nutr. Lab. Bronx VA Medical Center) : Nutrition Cultism - Facts & Fictions. 1981]
Vitamin B17 (Laetrile)
Laetrile is the trademark of a compound of two parts glucose and one part cyanide. There is no vitamin B17, "B17" is a tradename created for laetrile by a laetrile proponent. It is naturally present in the kernels of apricot pits and a number of other stone fruits and nuts. There is no RDA but doses vary from 0.25 g to 1.0 g a day.
It is believed to have cancer controlling and preventative properties. Apparently normal cells can tolerate small quantities of cyanide but cancer cells succumb to it.
Cyanide has no value in sustaining human life. In small amounts it injures, in larger amounts it kills. No law prevents promoters from trade-naming nutritionally worthless or poisonous substances.
Cyanide is rapidly absorbed from the intestine and diffuses throughout the body, knocking out respiration in cells. Eating about 25 apricot kernels can cause headaches, dizziness, nausea, drowsiness, a sharp fall in blood pressure, breathing difficulties, coma and death.
There have been documented cases of people dying after taking as few
as five laetrile tablets. Not more than 1.0 gram should be taken at any
one time. [
Herbert, J., (Chief Hematology & Nutr. Lab. Bronx VA Medical Center) : Nutrition Cultism - Facts & Fictions. 1981]
Vitamin C (Ascorbic Acid)
Ascorbic acid is water soluble and is easily lost from the body. The RDA for adults is 60 milligrams.
It is important for the growth and repair of body tissue cells, bones, gums and teeth. It fights bacterial infections, protects Vitamin A, some of the B vitamins and vitamin E from oxidation and is necessary for the use of iron and oxygen in the body. People who lack this vitamin may have sore gums and bleeding under the skin.
It helps to reduce blood cholesterol levels, aids in preventing bacterial and viral infections, and prevents and cures scurvy.
The best natural sources are citrus fruits, hot chili peppers, broccoli, tomatoes, green leafy vegetables, and sweet potatoes.
Vitamin C is non toxic but people with peptic ulcers, might hemorrhage and should consult a doctor before taking supplements. It is lost through water, destroyed by cooking, heat, light and smoking.
Vitamin D (Calciferol)
Vitamin D is a fat soluble vitamin and can be produced in the skin with exposure to sunlight. The RDA for adults is 10 micrograms or 400 IU. (as cholecalciferol. 10 micrograms cholecalciferol = 400 IU of vitamin D.]
It regulates calcium and phosphate metabolism. Aids the assimilation of vitamin A and helps the treatment of conjuctivites and rickets.
The best natural sources are sardines, herring and dairy products. It is produced by interaction with sunlight and oils (cholesterol) in the skin.
It can be toxic with doses of over 5000 IU daily. In smog conditions or when activities reduce exposure to sunlight vitamin D intake should be increased.
Vitamin E (Tocopherol)
Vitamin E is the term used for eight naturally occurring, fat-soluble nutrients called tocopherols - alpha, beta, gamma, delta, epsilon, zeta, eta and theta. Alpha-Tocopherol is essential, has the highest biological activity, and predominates in many species. The RDA for adults is 10 IU. (Designated according to its biological activity in International Units (IU). With this vitamin 1 IU = 1 mg Alpha Tocopherol Equivalents).
In human beings, vitamin E is the most important fat-soluble antioxidant. It prevents the potentially harmful oxidation of fat compounds and enhances the functioning of vitamin A. It is an antipollutant for the lungs. It helps the healing of scar tissue when taken internally and also when applied externally.
The best natural sources are wheat germ, whole grains, vegetable oils, soya beans, nuts, apples, apricots and green vegetables.
Vitamin E deficiency may cause anemia, as a result of red blood cell destruction and neurological dysfunction, myopathies, and diminished erythrocyte life span. New clinical evidence from heavy drinkers suggests that alcohol may increase oxidation of Alpha-Tocopherol. Increased demand has also been observed in premature infants and patients with malabsorption.
It is generally non toxic but some evidence suggests that large intakes may cause increased levels of blood cholesterol and lipids. It can oxidize within a few months of being manufactured, so supplements should not be stored for more than a few months. It is destroyed by heat, freezing, food processing, chlorine and iron.
Vitamin K (Menadione)
Vitamin K is a fat soluble vitamin usually formed in the body by intestinal bacteria but also available from some plant and animal sources. The RDA for adult males is 80 micrograms.
Its primary function is to control the rate of blood clotting and prevent internal bleeding.
The best natural sources are all leafy green vegetables, cauliflower, brussel sprouts, broccoli, soybean oil, kelp, cereal grain products, fruits and yoghurt.
Vitamin K deficiency has been reported in patients treated with antibiotics and placed on poor diets after surgery. A deficiency can cause bleeding disorders. Doctors sometimes give women vitamin K before childbirth to prevent bleeding in the newborn baby. Babies do not have enough intestinal bacteria to produce adequate amounts of the vitamin until they are about 2 weeks old.
No toxicity symptoms have been recorded from natural forms but supplementation of synthetic vitamin K exceeding 500 mcg is not recommended as it can cause anemia and kernicterus, a condition characterized by jaundice.
Biotin is a member of the B complex family and is water soluble. The RDA for adults is 100 micrograms.
It is essential for the metabolism of fats and the synthesis of ascorbic acid. It maintains a healthy skin and helps prevent baldness and hair from turning grey.
The best natural sources are soya beans, brown rice, nuts, fruit, brewer's yeast and milk. It can be synthesized by intestinal bacteria.
It is not toxic. Avidin, a substance found in egg white prevents biotin absorption. Sulfur drugs, food processing and alcohol destroy biotin.
Choline is a cofactor of the B vitamins. There is no RDA but the average adult diet contains between 500 milligrams to 900 milligrams a day.
Choline exists in combination with phospholipids which make up part of the brain and spinal cord tissue. These compounds are called lecithins. It is essential for growth and is involved in fat transport and in carbohydrate and protein metabolism. It participates in the metabolism of fat and emulsifies cholesterol, helping to control the build up in arteries. It aids in the treatment of Alzheimer's disease and helps to remove drugs and poisons from your system. It is also the precursor of acetylcholine, which is involved in the transmission of nerveimpulses. It is crucial for normal brain functioning and memory. It goes directly into the brain cells and produces a chemical that aids memory.
The best natural sources are soya lecithin, green leafy vegetables, yeast and wheat germ.
There is no known toxicity. It is destroyed by sulfur drugs, food processing and alcohol.
Folic Acid (Folate, Folacin)
Folic acid is a cofactor of the B complex vitamins. The RDA for adults is 200 micrograms.
Folate is essential for cell growth because of its involvement in nucleic acid and protein synthesis, and for the formation of red blood cells and protein metabolism. It protects the body against intestinal parasites and food poisoning. Maintains a healthy skin and helps in the treatment of anemia.
Megaloblastic anemia caused by folate deficiency is a major problem in world health, especially among pregnant women and patients with malabsorption or alcoholism.
The best natural sources are raw leafy vegetables, fruit, carrots, torula yeast, avocados, beans and whole wheat. Consumption of fresh fruit and green leafy vegetables daily will ensure against dietary folate deficiency.
In doses of up to 5 mg a day there has been no sign of toxicity.
It is easily lost in boiling water, sunlight, food processing, heat and by taking sulfur drugs. A heavy drinker also needs to increase folic acid intake.
Inositol is a cofactor of the B complex vitamins. There is no RDA but the average adult gets about 1 gram per day in their diet.
It works with choline in the metabolism of fat and cholesterol. It is essential for the proper conduction of nerve impulses, lowers cholesterol levels, promotes healthy hair and prevents balding.
The best natural sources are lecithin, brewer's yeast, lima beans, peanuts, raisins, wheat germ, cabbage, cantaloupe, grapefruit and molasses.
It is not toxic but is destroyed by sulfur drugs, food processing, alcohol and coffee.
PABA (Para-aminobenzoic Acid)
PABA is another member of the B complex family of vitamins. There is no RDA but about 100 milligrams is usually included in B complex supplements.
It helps in the assimilation of protein and pantothenic acid. It is important for normal skin and hair growth. It can protect you against sunburn, prevent wrinkles, reduce the pain of burns and restore grey hair to its natural color.
The best natural sources are whole grains, wheat germ, brewer's yeast, rice and molasses.
Non toxic, but high doses over a long period of time may cause nausea and vomiting.