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The story behind the Bs is nothing if not complex, starting with which nutrients fall into the B category at all.

“The vitamin B-complex consists of 11 nutrients that have similar roles in acting as coenzymes in production of energy and in the metabolism of proteins, fats and carbohydrates,” explains Tom Petrie, BS, CDN, nutritionist at the Schachter Center for Complementary Medicine in Suffern, N.Y. But, those 11 nutrients are divided between the eight classic Bs — B-1, B-2, B-3, B-5, B-6, B-7, B-9 and B-12 — and the three nutrients that are considered honorary B vitamins because they meet some but not all of the requirements of a classic B: para-amino benzoic acid (PABA), inositol and choline.

A note of caution: If you are at high risk for a disease and are using B vitamins in any therapeutic capacity, you should consult a physician who can take note of your risk factors — including family history and genetic profile.

Recommended Dosages for B Vitamins

B-1 (Thiamin)

Recommended Daily Allowance (RDA): 1.4 milligrams (mg)
*Recommended by Integrated Medicine Specialist (IMS): 15–50 mg

Role in Health: Facilitates smooth functioning of enzymes necessary for function of muscles, nerves and heart. Has been used in treating cancer, heart disease and Alzheimer’s disease. Useful in aiding emotional balance.

Best Food Sources: Sunflower seeds, peanuts, soybeans, whole wheat and nuts.

Signs of Deficiency: Lack of B-1 has a marked effect on the central nervous system, and a thiamin-deficient person may experience fatigue, memory loss, depression, headache and muscle weakness. Severe deficiency can result in neurological problems and cardiovascular problems, anorexia, weight loss, confusion, and depression.

B-2 (Riboflavin)

RDA: 1.1 milligrams, women; 1.3 milligrams, men
*IMS: 10–50 mg

Role in Health: Helps maintain health of skin, eyes and nerves. Helps produce niacin (B-3) and pyridoxine (vitamin B-6) from certain amino acids. Used to treat migraines.

Best Food Sources: Yeast, organ meats, almonds, mushrooms, whole grains, eggs, soybeans and green leafy vegetables.

Signs of Deficiency: Severe deficiency may result in the condition called ariboflavinosis, marked by a sense of weakness, sore throat, mouth problems — including crusty material at the corners or a red tongue — and, in the worst cases, anemia. Those at risk include people with anorexia or those following an extremely low-fat diet.

B-3 (Niacin)

RDA: 14 milligrams, women; 16 milligrams, men
*IMS: 20 to 150 mg. Different forms of niacin (nicotinic acid vs. niacinamide) are recommended depending on the condition being treated.

Role in Health: Important for health of the digestive system, skin, eyes and hair. In higher doses, niacin may help lower LDL (“bad” cholesterol) and triglycerides while raising HDL (“good” cholesterol) by 15 to 35 percent. Protective for the heart. Essential for manufacture of adrenal hormones and red blood cells. Also important for utilizing fats and carbohydrates. Has been used to facilitate wound healing.

Best Food Sources: Liver and other organ meats, eggs, fish, and peanuts.

Signs of Deficiency: In the beginning, B-3 deficiency may manifest initially through weakness, sore mouth and tongue, and weight loss. In later stages, deficiency may include diarrhea, inflammation of the skin and mental confusion. Deficiency may follow a serious gastrointestinal illness or alcohol consumption that impedes absorption.

B-5 (Pantotahenic Acid)

RDA: 4–7 milligrams
*IMS: 5 to 10 mg.

Role in Health: Essential for manufacture of adrenal hormones and red blood cells. Also important for utilizing carbohydrates, proteins and fats. Has been used to lower cholesterol and help treat wounds.

Best Food Sources: Liver and other organ meats, milk, legumes, fish, poultry and vegetables.

Signs of Deficiency: Deficiency of this B vitamin is reportedly rare, but those with inadequate amounts can experience fatigue, nausea, and the feeling of pins and needles in hands and feet.

B-6 (Pyridoxine)

RDA: 1.5 milligrams, women; 1.7 milligrams, men
*IMS: 25–100 mg

Role in Health: Helps to form the neurotransmitters serotonin, dopamine and norepinephrin, which are essential for mental health, and the enzyme insulin, which maintains normal levels of blood sugar. Important to the health of red blood cells, the immune system and infection-fighting antibodies. Has been used to treat fatigue and protect the heart.

Best Food Sources: Whole grains, legumes, bananas, seeds and nuts, potatoes, Brussels sprouts, and cauliflower.

Signs of Deficiency: Deficiency of B-6 can cause a progressive series of problems. Initially, vague symptoms include insomnia, fatigue, depression, gastrointestinal pain and slow wound healing. As time goes on, deficiency can cause anemia and elevated cholesterol. In the latest stages, deficiency can lead to neurological symptoms, seizures and kidney stones.

B-7 (Biotin)

RDA: No RDA, but the Food and Nutrition Board of the Institute of Medicine recommends 35 to 60 micrograms (mcg) a day.
*IMS: 100–400 mcg

Role in Health: Required for synthesis of fatty acids. Also helps to manufacture proteins and in gene expression. Has been used to treat hair loss and brittle fingernails and to stimulate production of insulin in diabetics.

Best Food Sources: Brewer’s yeast, organ meats and soybeans.

Signs of Deficiency: Anemia, pale or flaking skin, pins-and-needles sensation in the fingers and toes, and sore tongue are some of the symptoms of biotin deficiency.

B-9 (Folate or Folic Acid)

RDA: 400 micrograms
*IMS: 400–1,200 mcg. Natural folate sources preferred over synthetic folic acid.

Role in Health: Makes red blood cells. According to some studies, up to 800 micrograms of B-9 a day — either from food or a supplement — may help ward off cognitive decline and even reduce the risk of Alzheimer’s disease. For older adults, those who consume alcohol and others who may not get or absorb enough folate, supplements may reduce risk of cancer, especially colon and breast, and may help reduce risk of heart disease. May also help reduce risk of cardiovascular disease.

Best Food Sources: Green leafy vegetables such as spinach, kale, beet greens and Swiss chard; and asparagus and avocados.

Signs of Deficiency: Those deficient in folic acid may develop anemia and low white-blood-cell counts. Pregnant women are always given B-9 supplements, because deficiency can lead to neural tube deficits, including spina bifida, in the fetus.

B-12 (Cyano-Cobalamin)

RDA: 2.4 micrograms
*IMS: 400–1,000 mcg

Role in Health: Makes red blood cells. Essential for cell metabolism and function of the nervous system and brain. Older adults should routinely consume extra B-12 from fortified foods or supplements to prevent deficiency. Used to treat fatigue and depression; protects the heart; has been seen as a useful adjunct in cancer treatment.

Best Food Sources: Liver, kidney, fish, eggs, poultry, meat and dairy products.

Signs of Deficiency: Those with B-12 deficiency may experience fatigue, pale complexion and anemia. Men with B-12 deficit may suffer low sperm counts and problems with infertility. Severe B-12 deficiency has been associated with higher risk of esophageal cancer.


*IMS: 50 mg

Role in Health: Known for antioxidant properties; also blocks ultraviolet light from the sun.

Best Food Sources: Organ meats, wheat germ, whole grains, eggs and brewer’s yeast.

Signs of Deficiency: Deficiency has never been recorded in humans.


*IMS: 150–500 mg

Role in Health: Primary component of cell membranes and important for cell division. Works with choline to help transport fat from the liver. Helps to control blood cholesterol levels. Used in supplement form to treat anxiety, and panic and obsessive compulsive disorder.

Best Food Sources: Whole grains, fruits, meats, dairy products and yeast. Egg yolks, organ meats, legumes and lecithin.

Signs of Deficiency: Deficiency has never been recorded in humans.


Technically not a vitamin, but often considered to be part of the B family. Works with inositol.

RDA: No RDA, but the Food and Nutrition Board of the Institute of Medicine recommends 125 to 550 micrograms a day.
*IMS: 50–500 mcg

Role in Health: Needed as primary building block of the neurotransmitter acetylcholine, essential for the cognitive and motor functions of the nervous system. Together with inositol, has been effectively used to treat premenstrual syndrome.

Best Food Sources: Egg yolks, organ meats, legumes, peanut butter, lettuce, cauliflower and lecithin.

Signs of Deficiency: Since choline is produced by the body itself, severe deficiency is extremely rare; because it is required by every cell, the outcome of such a deficiency would be fatal.

*Recommended by Integrated Medicine Specialist: Depending upon practitioner and nutritional profile of client.

Too Much of a Good Thing?

We know the B vitamins are critical to our health and well-being, but is it possible to overdo them? Take a look at the list below to find out.

  • B-1, Thiamin: No known adverse reactions to higher doses recorded in the literature.
  • B-2, Riboflavin: Intake many times higher than the RDA causes no known adverse reactions, but possible reactions to much higher doses include numbness, itching, burning/prickling sensations and dark yellow urine.
  • B-3, Niacin: If you buy your B-3 over the counter and treat yourself, you’re unlikely to have side effects with daily intake below 50mg. If you require more, make sure you are under a doctor’s supervision, because side effects, especially facial flushing, may result. If you are on niacin therapy, be sure to monitor liver enzymes.
  • B-5, Pantothenic acid: No known adverse reactions to moderate doses. However, larger doses may cause diarrhea and actually inhibit the absorption of B-7, Biotin.
  • B-6, Pyridoxine: Large doses of over 100 mg daily, taken over long periods of time, may cause nerve damage.
  • B-7, Biotin: Biotin is not known to be toxic. Oral biotin supplementation has been well tolerated in doses up to 200,000 mcg/day in people with hereditary disorders of biotin metabolism. In people without disorders of biotin metabolism, doses of up to 5,000 mcg/day for two years were not associated with adverse effects.
  • B-9, Folate or folic acid: High doses of B-9 can mask a B-12 deficiency, allowing associated nerve and cognitive deterioration to proceed unchecked. This can be remedied by taking a supplement that contains 100 percent of the Recommended Daily Allowance of both B-9 and B-12.
  • B-12, Cyano-cobalamin: No known adverse reactions to higher doses.
  • PABA: Can damage the liver at high doses. Also associated with nausea, vomiting and allergic-type reactions. Can block action of sulfa-containing antibiotics.
  • Inositol: High doses may result in diarrhea.
  • Choline: High doses (10 to 16 grams/day) have been associated with a fishy body odor, vomiting, salivation and increased sweating.

This was excerpted from “All About B Vitamins” which was published in the September 2010 issue of Experience Life magazine.

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