Vitamins are organic compounds that are necessary for life required in small amounts and must be obtained in the diet (except for vitamin D which can be made with the aid of sunlight) as the body cannot make them from other nutrients. In this definition, "organic" refers to the fact that they contain carbon atoms and has nothing to do with the fertilizers used to nourish the foods from which they are derived or whether or not they are grown with or without pesticides. Vitamins A, D, E and K are fat-soluble vitamins. The B-complex vitamins and vitamin C are water-soluble vitamins.
Vitamin A (Retinol)
Function: Vision; growth and development; strengthens immune system-especially respiratory tract and mucous membranes; antioxidant
Sources:Liver, chili peppers, carrots, vitamin A-fortified milk, butter, sweet potatoes, parsley, kale, spinach, mangoes, broccoli, squash
RDA: Men 5,000 IU; Women 4,000 IU
Optimal intake: Adult men: 5,000 IU; Adult women: 2,500 IU
Deficiency Signs Night blindness, infectious disease susceptibility, follicular hyperkeratosis (bumps on the skin-mainly, the back of the upper arm, the shoulders, the neck, the buttocks, and the lower abdomen), faulty tooth and bone formation, impaired growth.
Toxicity: Overdoses of vitamin A can produce symptoms of vomiting, joint pain, abdominal pain, bone abnormalities, cracking, dry skin, headache, irritability, and fatigue. Symptoms disappear after supplementation has been discontinued. Pregnant women or those with liver disease should avoid vitamin A supplementation dosages above 2,500 IU.
Vitamin Bl (Thiamin)
Function: Energy metabolism (carbohydrate metabolism), neurological activity, brain and heart function
Sources: Pork, beef, liver, brewer's yeast, whole grains, brown rice, legumes
Optimal intake: 5 to 10 mg
Deficiency Signs: Beriberi, a condition characterized by fatigue, anorexia, weight loss, gastrointestinal disorders, fluid retention, weakness, heart abnormalities, stunted growth, cyanosis, convulsions and poor memory
Toxicity: None reported
Vitamin B2 (Riboflavin)
Function: Energy production, fatty acid and amino acid synthesis
Sources: Organ meats such as liver, milk products, whole grains, green leafy vegetables, eggs, mushrooms, broccoli, asparagus, fish
Optimal intake: 10-15 mg
Deficiency Signs: Cracking at the corners of the mouth, inflamed tongue, reddening of the eyes, vision problems, dermatitis, nerve damage, decreased neurotransmitter production, malformations and retarded growth in children and infants
Vitamin B3 (Niacin)
Function: Energy production, formation of steroid compounds, red blood cell formation, cognitive function and mood.
Sources: Organ meats, peanuts, fish, yeast, poultry, legumes, milk, eggs, whole grains, orange juice
Optimal intake: 50-100 mg
Deficiency Signs: Pellagra, a condition characterized by dermatitis, diarrhea, dementia; depression, schizophrenia, weakness, lassitude, anorexia
Toxicity: Large doses can cause dilation of the blood vessels and flushing of the skin. Use a non-flushing form (inositol hexaniacinate) if you are sensitive to regular niacin. Time-released niacin products may result in liver damage.
Vitamin B5 (PantothenicAcid)
Function: Metabolism of carbohydrates, proteins, and fats for energy production; production of adrenal hormones and red blood cells
Sources: Organ meats, fish, chicken, eggs, cheese, whole grains, avocados, cauliflower, sweet potatoes, oranges, strawberries, yeast, legumes
Optimal intake: 50-100 mg
Deficiency Signs: Numbness and shooting pains in the feet; fatigue
Toxicity: None reported
Vitamin B6 (pyridoxine)
Function: Formation of body proteins, neurotransmitters, red blood cells; immunity
Sources: Meats, poultry, egg yolk, soy, peanuts, bananas, potatoes, whole grains, cauliflower.
Optimal intake 10 – 25mg
Deficiency Signs: Mood abnormalities sleep problems, anemia, and impairment of nerve function eczema, cracking of the lips and the tongue, premenstrual syndrome, depression
Toxicity: Very high dosages can cause nerve symptoms-numbness and tingling
Vitamin B12 (Cobalamin)
Function: Synthesis of DNA, red blood cells; nerve development
Sources: Gut bacteria synthesis, organ meats, clams, oysters, soy, milk products, cheese, chlorella, spirulina
Optimal intake: 50-200 micrograms (mcg)
Deficiency Signs: Macrocytic anemia; glossitis; spinal cord degeneration; digestive upset; fatigue; mental abnormalities, including irritability, depression
Function: Metabolism of fats, proteins, and carbohydrates; nail and hair growth
Sources: Gut bacterial synthesis, organ meats, cheese, soybeans, eggs, mushrooms, whole wheat peanuts
Optimal intake: 300 micrograms (mcg)
Deficiency Signs: Seborrheic dermatitis (cradle cap) and hair loss in infants; brittle nails and hair
Toxicity: None reported
Vitamin C (Ascorbic Acid)
Function: Antioxidant, immunity, collagen formation, bone development, cancer prevention and treatment, gum health, hormone and amino acid synthesis, adrenal gland hormones, wound healing
Sources: Citrus fruits, tomatoes, green peppers, dark-green leafy vegetables, broccoli, cantaloupe, strawberries, brussels sprouts, potatoes, asparagus
Optimal intake: 500-1,500 mg
Deficiency Signs: Scurvy, signs of which include bleeding gums, poor wound healing, joint tenderness and swelling, recurrent infections, and profuse bruising
Toxicity: The first symptom of too much vitamin C is generally diarrhea, which disappears when the dosage is reduced.
Examples of carotenoids include beta carotene, alpha carotene, gamma carotene, beta zeacarotene, cryptoxanthin, lycopene, zeaxanthin, lutein, canthaxanthin, crocetin, capsanthin.
Function:There are over 600 identified carotenoids. Approximately 50 act as precursors to vitamin A. Carotenoids are potent antioxidants, help with immune function, and are involved with the growth and the repair of tissues.
Sources: Yellow vegetables (carrots, pumpkins, squash, sweet potatoes); green vegetables (broccoli, peas, collard greens, endive, kale, lettuce, peppers, spinach, turnip greens); fruits (apricots, cantaloupe, papaya, peaches, watermelon, cherries, tomatoes)
RDA: None established
Optimal intake: 5,000 to 25,000 IU of mixed carotenoids
Deficiency Signs: Increased susceptibility to developing certain cancers and cardio- vascular disease
Toxicity:Relatively nontoxic. Too high of an intake can lead to carotenemia (yellowing of skin), which disappears after reduction of carotenoid intake.
Vitamin D (Vitamin D2-Ergocalciferol, Vitamin D3-Cholecacliferol)
D2-derived from plant sources
D3-derived from animal sources
Function: It promotes calcium and phosphorous absorption from intestines, increases calcium deposition into bones, mobilizes calcium and phosphorous from bones. It prevents certain cancers and is required for proper thyroid function.
Sources: Cod liver oil, cold-water fish (salmon, herring, sardines, mackerel), milk (fortified with vitamin D), egg yolk, small amounts in dark-green leafy vegetables and mushrooms. Sunlight is converted into vitamin D.
Optimal intake: 400 to 800 IU
Deficiency Signs: Rickets-softening of the skull bones, bowing of the legs, spinal curvature, a contracted pelvis, abnormal enlargement of the head, and an increased joint space, delayed tooth eruption; osteoporosis
Toxicity: Nausea, anorexia, weakness, headache, digestive disturbance, kidney damage, calcification of soft tissues, and hypercalcemia
Vitamin K (Phylloquinone, Menaquinone)
Phylloquinone = Kl, derived from plants
Menaquinone = K2, derived from gut bacteria
Menadione = K3, derived synthetically
Function:Blood clotting, bone formation, antioxidant
Sources: liver, legumes, and synthesized by intestinal bacteria
Optimal intake: 50 to 100 mcg
Deficiency Signs: Blood-clotting problems, osteoporosis, menstrual cramps
Toxicity: Hemolytic anemia
Vitamin E-Complex (Tocopherol, Tocotrienols)
Includes alpha, beta, and gamma tocopherol, as well as tocotrienols. Most supplements refer to alpha tocopherol.
Function:Antioxidant, immunity, wound healing, red blood cell formation, estrogen metabolism, nerve health
Sources: Vegetable oils, seeds, nuts, brown rice, and whole grains
Optimal intake: 400 IU
Deficiency Signs: Severe deficiency is rare. Dry skin, hemolytic anemia of newborns, muscle and neurological disorders.
Folic Acid (Folacin, Folate)
Function: Prevents neural tube defects (must be taken by the mother in early pregnancy). Methyl donor that is required for many processes in the body (reduces homocysteine levels). Cardiovascular health, red blood cell production, skin and nail health.
Sources:Dark green vegetables-spinach, kale, broccoli, asparagus-as well as organ meats, kidney beans, beets, yeast, orange juice, whole grains
Optimal intake: 400 to 800 micrograms (mcg)
Deficiency Signs: Macrocytic anemia, fatigue, irritability, weakness, weight loss, anorexia, dyspnea, sore tongue, palpitations, forgetfulness, digestive upset, diarrhea
Inositol is usually considered part of the vitamin B complex. It is thought that, along with choline, inositol is necessary for the formation of lecithin within the body.
Niacin, also available in the form of niacinamide, is a coenzyme that assists in the breakdown of carbohydrates, fats and proteins. Niacin is essential for the health of the skin, tongue and digestive system. The disease, pellagra, is a result of a niacin deficiency.
PABA (para-aminobenzoic acid) may be considered part of the vitamin B complex. It influences intestinal bacteria, enabling them to produce folic acid, which in turn, aids in the production of pantothenic acid. As a coenzyme, PABA functions in the breakdown and utilization of proteins, and aids in the formation of red blood cells.
Pantothenic acid is necessary for the normal functioning of the adrenal gland which directly affects growth. It is also essential for the formation of fatty acids. In addition, as a coenzyme, it participates in the utilization of riboflavin and in the release of energy from carbohydrates, fats and proteins.