Vitamins – A Quick Reference Guide
Vitamins are organic molecules that are essential to metabolism in all living organisms. While these molecules serve essentially the same role in all forms of life, higher organisms have lost the ability to synthesize (make) many vitamins. Vitamins are found in the foods we eat, or in supplement form. A lack of proper amounts of vitamins in the diet leads to a host of vitamin-deficiency caused diseases. The RDA or Recommended Daily Allowance was established to guard against deficiency-related diseases. Many authorities feel that RDA levels are too low and that good health requires substantially more nutrients than the current recommendations, and many aliments are treated with high dosages of vitamins. The Upper Limit (UL) is the upper level of Intake considered to be safe for use by adults; however, you may find many references where higher amounts are used successfully. There are two major groups of vitamins, the fat-soluble vitamins designated by the letters A, D, E, and K, and the water-soluble vitamins, which are referred to as the vitamin B complex and vitamin C. Excesses of water-soluble vitamins are flushed from the system in urine, making them very safe at higher doses. Fat-soluble vitamins, on the other hand, are stored in the body’s fatty tissues and may reach toxic levels over time when consumed in mega-quantities.
Vitamin A (RDA: Women – 4000 IU, Men – 5OOO IU) (UL: 10,000 IU)
Although vitamin A is probably best known for promoting and maintaining healthy eyesight, it has other important functions as well. One of its major contributions is to improve the body’s resistance to infection. It does this in part by maintaining the health of the skin, mucous membranes, and other surface linings (intestinal tract, urinary tract, respiratory tract) so that harmful bacteria and viruses can’t get into your body. Vitamin A also boosts immunity by enhancing the infection-fighting actions of the white blood cells called lymphocytes. Vitamin A is also vital to the growth of bones, the division of cells in your body, and to human reproduction.
Vitamin B1 (thiamin) (RDA: Women – 1.1 mg, Men – 1.2 mg) (UL: Not Established)
This nutrient is essential to normal growth and development. It participates in converting carbohydrates from foods into energy and promotes proper functioning of the heart and nervous systems. Thiamin may lessen numbness and tingling in individuals with diabetes and other disorders that can cause nerve damage.
Vitamin B2 (Riboflavin) (RDA: Women – 1.1 mg, Men – 1.3 mg) (UL: Not Established)
Vitamin B2, a water-soluble member of the B-complex family of vitamins, plays a crucial role in converting protein, fats, and carbohydrates into the energy that the body demands to grow and develop property. Along with Vitamin B6 and niacin, riboflavin protects the nervous system. Vital to maintaining proper metabolism, riboflavin also helps to shore up the immune system by reinforcing antibody reserves. Along with iron, riboflavin is essential for producing the red blood cells that carry oxygen throughout the body. In addition, the body uses extra riboflavin to keep tissue in good repair and speed healing of wounds, burns and other injuries.
Vitamin B3 (niacin) (RDA Women – 14 mg, Men – 16 mg) (UL: 35 mg)
Also known as Vitamin B3, niacin has earned a reputation (in supplement form) as a natural cholesterol lowering agent. It may also help to prevent or treat a number of other disorders, from arthritis and depression to diabetes. This vitamin is also critical to releasing energy from carbohydrates and helping to control blood sugar levels. Interestingly, the body also synthesizes niacin from tryptophan, an amino acid found in eggs, milk and poultry. Although few people in the industrialized world are actually deficient in niacin, many may benefit from additional amounts in supplement form to help treat assorted complaints. Keep in mind that each of the three forms of niacin affects the body differently. Niacinamide has notable anti-inflammatory properties, for example, while nicotinic acid and inositol hexaniacinate affect blood lipid levels and circulation.
Vitamin B5 (pantothenic acid) (4 – 7 mg*) (UL: Not Established)
Also known as Vitamin B5, pantothenic acid is essential for a number of basic bodily functions -from growth to reproduction. It participates in the continual breakdown of carbohydrates, fats, and proteins from food. This vitamin also produces numerous enzymes and helps maintain precise communication between the central nervous system and the brain. A deficiency of pantothenic acid is quite rare in humans because a large number of foods contain this vitamin. In fact, the name is derived from the Greek pantos, meaning everywhere. Even so, a supplement may be needed to get the higher doses of pantothenic acid recommended for the treatment of specific ailments. Pantothenic acid comes in two forms: calcium pantothenate and pantethine. The former is widely used for treating ailments from stress to heartburn, while pantethine is mainly recommended for lowering blood cholesterol levels in those who don’t respond to other natural treatments. Many multivitamin and Vitamin B complex supplements contain pantothenic acid.
*No RDA for Vitamin B5 has been established. Amounts listed are based on the Food and Nutrition Board’s Safe and Adequate Daily Amounts.
Vitamin B6 (pyridoxine) (RDA: Women – 1.5 mg, Men – 1.7 mg) (UL: 100 mg)
Day by day, there’s probably no nutrient as actively involved in keeping your system running smoothly as Vitamin B6. Technically an umbrella term used to describe three B vitamins (pyridoxine, pridoxal, and pyridoxamine); Vitamin B6 partakes in no fewer than 100 chemical reactions throughout the body. Vitamin B6 helps manufacture the building blocks of proteins known as amino acids. It also takes part in producing brain neurotransmitters (chemical messengers) and in manufacturing red blood cells. Vitamin B6 also helps to keep hormones in balance and the immune system functioning properly. Taken as part of a vitamin B-complex supplement, Vitamin B6 may help protect against heart disease and a host of other disorders. Vitamin B complex supplements may also minimize memory loss associated with the early stages of Alzheimer’s disease. B6 deficiency may cause sleep problems. B6 along with niacinamide, which reduces anxiety, may provide some relief from insomnia.
Vitamin B12 (cobalamin) (RDA: Adults – 2 mg) (UL: Not Established)
In 1948, scientists were successful in identifying a nutritional substance in calf’s liver that could prevent pernicious anemia, a potentially deadly disorder that mainly affects older adults. The compound vitamin B12 (or cobalamin), turned out to be the last vitamin to be discovered. Other groups are also at particular risk for a deficiency: those with ulcers, Crohn’s disease or other gastrointestinal disorders, and those taking medication for epilepsy, chronic heartburn, or gout. Heavy drinkers are likely to have low levels of B12 because excessive alcohol consumption hinders the nutrient’s absorption. People who don’t eat any animal products (vegans) are also at risk. A deficiency can cause fatigue, depression, confusion, memory loss, muscle weakness, and numbness and tingling in the hands and feet due to nerve damage. Not only does Vitamin B12 help in the formation of healthy red blood cells, it is also involved in the maintenance of the myelin sheath that enables nerves to function properly. We also need this vitamin for cell replication, energy metabolism, and to create DNA and RNA In cells. Vitamin B12 is the only B vitamin that the body stores in substantial amounts.
Folic Acid (folate) (RDA: Adult – 400 mcg) (UL: 1000 mcg)
Folic acid, also called folate or folacin, is a B vitamin with a solid reputation for protecting against birth defects and heart disease. With adequate amounts of folic acid, it is estimated that 50,000 deaths from cardiovascular disease could be prevented each year in the United States alone. Moreover, common birth defects could be cut nearly in half. Other ailments, such as depression, and Alzheimer’s disease, may respond to the effects of folic acid as well.
Folic acid is involved in every bodily function that requires cell division. It is used to generate red blood cells, help wounds heal, build muscle, and produce brain and nervous system chemicals. It should always be taken in combination with Vitamin B12, because taking only one of these B vitamins can mask a deficiency in the other.
Biotin (RDA Not Established) (UL: Not Established)
Although biotin is one of the lesser known B vitamins, it plays an essential role in a number of important body processes. This nutrient assists the body in metabolizing protein, fats, and carbohydrates from food. It plays a special role in enabling the body to use blood sugar (glucose). Biotin also helps produce certain enzymes. When low levels of biotin do occur, problems such as brittle nails and lackluster hair can develop.
Choline (RDA Not Established) (UL: 3500 mg.)
Choline helps form phosphatidylcholine, the primary phospholipid of cell membranes. Choline is also the precursor to acetylcholine, one of the important brain chemicals involved in memory. This nutrient, usually as part of phosphatidylcholine, is widely available in a number of foods, particularly eggs, fish, legumes, nuts, and meats and vegetables, as well as in human breast milk.
PABA (RDA Not Established) (UL: Not Established)
An abbreviation for para-aminobenzoic acid, PABA, appears to be a component of folic acid, a member of the B family of vitamins. It plays a role in breaking down and using proteins, and in forming red blood cells. PABA is important for healthy hair and skin. PABA is synthesized naturally in the intestines from friendly bacteria, and can also be obtained through grains and animal products. Supplements are also available.
Inositol (RDA Not Established) (UL: Not Established)
Inositol is necessary for the formation of lecithin and functions closely with another B vitamin, choline. Since it is not essential in the human diet, it cannot be considered a vitamin. Inositol is a fundamental ingredient of cell membranes and is necessary for proper function of nerves, brain, and muscles in the body. Inositol works in conjunction with folacin, Vitamins B6 and B12, choline, betaine, and methionine to prevent the accumulation of fats in the liver. It exists as the fiber component in phytic acid, which has been investigated for its anti-cancer properties.
Vitamin C (RDA: Adults – 60 mg, Adults who Smoke – 100 mg.) (UL: 2000 mg.)
In the eighteenth century, seasoned sailors found that by sucking on lemons they could avoid scurvy. When the lemon’s key nutrient was formally identified in 1928, it was named ascorbic acid for its anti-scurvy, or antiscorbutic, action. Today ascorbic acid is widely known as Vitamin C. The health benefits of Vitamin C are abundant and varied, but it’s probably best known as a cell protector, immunity booster, and powerful antioxidant. The body’s ligaments, tendons, and collagen (a protein found in connective tissues) rely on the presence of Vitamin C to stay strong and healthy. Like all antioxidants, Vitamin C counters the effects of cell-damaging molecules called free radicals. As an added benefit, it even helps the body recycle other antioxidants. For certain conditions, Vitamin C is best taken with other antioxidants, such as Vitamin E, flavonoids, and carotenoids.
Vitamin D (RDA: 200 – 600 IU) (UL: 2000 IU)
Vitamin D is called the sunlight vitamin because the body produces it when the sun’s ultraviolet B (UVB) rays strike the skin. It is one of the few vitamins the body manufactures naturally and is technically considered a hormone. Essential for building strong bones and teeth, Vitamin D also helps to strengthen the immune system and may prevent some types of cancer. By promoting the absorption and balance of calcium and phosphorous in the body, Vitamin D strengthens the bones and teeth and also fosters normal muscle contraction and nerve function.
Vitamin E (RDA: Women – 12 IU, Men – 15 IU) (UL: 800 mg)
Vitamin E is actually an umbrella term for a group of compounds called tocopherols and tocotrienols. Until recently, most vitamin E products contained only tocopherols (alpha-, beta-, delta-, and gamma-tocopherols), with alpha-tocopherol recognized as the body’s predominant and most potent form. Researchers also identified heart-healthy powers in the tocotrienols. Combination products are available, although tocotrienols are easiest to find in single supplement form. To realize vitamin E’s full health benefits, you need both tocopherols and tocotrienols. As a powerful antioxidant, Vitamin E plays a vital role in protecting the body from many chronic disorders, slows the aging process, and guards against damage from secondhand smoke and other pollutants. The tocotrienols (alpha-tocotrienol, specifically) may be the most powerful of the Vitamin E antioxidants. Circulatory disorders, skin and joint problems, diabetes-related nerve complications, high cholesterol, endometriosis, immune-system function and memory are also believed to benefit from vitamin E.
Vitamin K (RDA: Women – 65 mcg, Men – 80 mcg) (UL: Not established)
In the 1930s, researchers in Denmark observed that chicks on a fat-free diet experienced bleeding problems. By 1939, they were successful in isolating an alfalfa-based compound that effectively stopped the bleeding. Because of its ability to help blood clot (called coagulation) this substance was named Vitamin K, for Koagulatlon. Vitamin K helps to prevent excessive bleeding and promote strong bones. Over time, scientists discovered that “friendly” bacteria in the intestinal tract produce sufficient quantities of this nutrient to meet most of our body’s needs. Another 20% of this fat-soluble vitamin is acquired from foods. Food Sources include spinach, broccoli, Brussels sprouts, cabbage, parsley, eggs, dairy products, carrots, avocados, and tomatoes.