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Herbal Medicine                                            
REF:  http://www.intelihealth.com/IH/ihtIH/WSIHW000/8513/31402.html    

Be aware that the U.S. Food and Drug Administration does not strictly regulate herbs and dietary supplements. There is no guarantee of strength, purity or safety of products containing or claiming to contain niacin. Decisions to use herbs or supplements should be carefully considered. Individuals using prescription drugs should discuss taking herbs or supplements with a pharmacist or health care professional before starting.

• Unproven Uses
• Potential Dangers
• Interactions
• Dosing
• Summary
• Resources

Evidence    

Vitamin B-3 is composed of niacin (nicotinic acid) and is a source of niacinamide. Scientists have studied niacin for the following health problems:

High cholesterol

Niacin has been observed to have substantial benefits in lowering high cholesterol levels. It is particularly effective in raising levels of high-density lipoprotein (HDL or "good cholesterol") levels, but it is less effective at lowering low-density lipoprotein (LDL or "bad cholesterol") levels than some other cholesterol-lowering drugs. Niacin is currently used as one of the first-line treatments of high cholesterol either alone or in combination with other cholesterol-lowering drugs. Niacinamide, which is also present in vitamin B-3, does not have the same effects as niacin on cholesterol levels. Some studies show that niacin can raise homocysteine levels, which may increase the risk of cardiovascular disease.

Pellagra (niacin deficiency)

Pellagra is a disease caused by niacin deficiency. Symptoms of pellagra include skin irritation, diarrhea, dementia or depression. The disease may affect chronic abusers of alcohol. However, diabetes, liver disease, pregnancy and some drugs may also cause niacin deficiency. Both niacin and niacinamide are approved by the U.S. Food and Drug Administration for treating niacin deficiency.

Atherosclerosis (clogged arteries), prevention of heart disease

Niacin has been shown to lower cholesterol levels. Lower cholesterol has been associated with slowing the progression of clogged arteries, and unclogged arteries lessen the risk of heart disease. However, niacin has also been shown to increase the levels of homocysteine, a compound in the blood that increases the risk of clogged arteries. Scientific evidence from studies in humans supports the use of niacin in combination with other drugs to reduce the risk of clogged arteries in people with high cholesterol. However, more research is needed to determine whether niacin can reduce clogged arteries and prevent heart disease and death when it is used alone.

Diabetes

Niacinamide, a chemical in vitamin B-3, has been proposed as a possible therapy to prevent diabetes or delay the need for insulin. Animal studies of niacinamide use in diabetes have suggested that it may increase the time that oral drug treatment is effective and delay the need for insulin injections. Research in humans has shown mixed results with niacinamide, and most studies had flaws in their designs. More research is needed to determine if niacinamide provides any advantages in delaying or preventing the onset of insulin dependence in individuals with diabetes. The use of niacin for the treatment of dyslipidemia associated with type 2 diabetes has been controversial because of the possibility of worsening glycemic control. However, a recent randomized, controlled, multicenter trial showed that of 148 patients in the study, only four discontinued because of inadequate glucose control. These researchers reported doses of 1,000 to 1,500 milligrams per day (in a controlled-release formulation) to be a treatment option for type 2 diabetics with dyslipidemia. Check with your physician and pharmacist before starting niacin.

Osteoarthritis

Results from one study suggest that niacinamide, a chemical in vitamin B-3, may help to improve flexibility, reduce inflammation and lessen the need for drugs that are commonly used for pain in people with osteoarthritis. The study was small, and more research is needed to determine if niacinamide provides benefits for this condition.

Alzheimer's disease, cognitive decline

Dementia can be caused by severe niacin insufficiency, but it is unknown whether variation in intake of niacin in the usual diet is linked to neurodegenerative decline. One large, prospective study examined whether dietary intake of niacin was associated with incident Alzheimer's disease and cognitive decline. The authors concluded that dietary niacin may protect against Alzheimer's disease and age-related cognitive decline. Further research is needed to confirm these results.

Unproven Uses    

Niacin has been suggested for many other uses, based on tradition or on scientific theories. However, these uses have not been thoroughly studied in humans, and there is limited scientific evidence about safety or effectiveness. Some of these suggested uses are for conditions that are potentially very serious and even life-threatening. You should consult a health care professional before taking niacin for any unproven use.

Acne Age-related macular degeneration Alcohol dependence Anti-aging Anxiety Arthritis Bell's palsy Brain disorders Cancer prevention Cataract prevention Chemotherapy side effects Circulation Deafness Depression Diarrhea Digestion Dizziness Drug-induced hallucinations Edema High blood pressure HIV treatment and prevention Hyperactivity Insomnia Intermittent claudication Ischemic injury prevention Leprosy Low blood sugar levels

Memory loss Ménière's syndrome Menstrual cramps Migraine headaches Motion sickness Multiple sclerosis Non-ST-segment elevation acute coronary syndromes Orgasm enhancement Peripheral vascular disease Photosensitivity Pregnancy Premenstrual syndrome Psoriasis Raynaud's phenomenon Ringing in the ears Schizophrenia Scleroderma Sedative Seizures Skin disorders Smoking cessation Tardive dyskinesia Taste disturbance (diminished/distorted sense of taste) Thyroid disease Tuberculosis Tumor detection Ulcers Vascular spasm

Potential Dangers    

Allergies

• People should avoid niacin/vitamin B-3 if they have a known allergy to niacin or niacinamide. Anaphylactic shock (a severe allergic reaction) has occurred. Signs of allergy may include rash, itching or shortness of breath.

Side Effects

• Niacin has been associated with many minor side effects. Some people may experience flushing, itching and stomach discomfort, including stomachache, nausea, vomiting and diarrhea. Niacin may also aggravate peptic ulcer disease. Most stomach-related side effects usually go away over time. Taking niacin with food may prevent stomach discomfort.
• Flushing or a warm sensation, especially on the face, neck and ears, occurs in almost all patients using niacin for the first time or at higher doses. This side effect usually goes away on its own after one or two weeks. Using aspirin or other nonsteroidal anti-inflammatory drugs such as ibuprofen can reduce the tingling, itching, flushing and warmth associated with niacin. Slow-release niacin formulations may have a lower incidence of flushing but may also be more likely to cause stomach upset and liver abnormalities.
• Other possible side effects include headache, dizziness, panic attacks, anxiety, difficulty breathing, irregular heartbeats and dental pain. Macular edema and blurred vision have also been reported. Niacin may also damage the liver. Periodic monitoring of liver function by a qualified health care professional is recommended. If you develop yellow skin or eyes or have pain in your abdomen, it is a good idea to contact a health care professional.
• Niacin increases blood sugar levels, which can be a concern for patients with diabetes and dyslipidemia. Theoretically, this could cause decreased glycemic control. However, a recent randomized, controlled, multicenter trial showed that of 148 patients in the study, only four discontinued because of inadequate glucose control. Doses of 1,000 to 1,500 milligrams per day (in a controlled-release formulation) were shown to be a treatment option for type 2 diabetics in this study. If you take drugs by mouth or use insulin to control your blood sugar levels and are considering using niacin, increased monitoring is necessary because doses of diabetic drugs may need to be adjusted. Ketones and sugar may be detected in the urine. Uric acid in the blood is increased and can aggravate or cause gouty attacks. Thyroid function may also be impaired while taking niacin. Periodic monitoring of thyroid function is recommended. If you take drugs to treat thyroid disease and are considering using niacin, discuss this with a health care professional.
• Other rare side effects reported in people using niacin are alterations in some blood cell counts, muscle pain and degeneration and metabolic abnormalities such as metabolic acidosis. Niacin may also increase the risk of bleeding. If you use anticoagulants (blood thinners) or antiplatelet drugs and are considering using niacin, discuss this with a health care professional. You may be advised to stop using niacin before some surgeries. Anaphylactic shock (a severe allergic reaction) from severe niacin allergies may also occur.

Pregnancy And Breast-Feeding

• Niacin cannot be recommended during pregnancy and breast-feeding because of a lack of information.

Interactions    

Interactions with drugs, herbs and other supplements have not necessarily been thoroughly studied. The interactions listed below have been reported in scientific publications. If you are taking prescription drugs, speak with a health care professional or pharmacist before using herbs or dietary supplements.

Interactions With Drugs

• When niacin is used with other cholesterol-lowering drugs, such as clofibrate, probucol, gemfibrozil (Lopid), cholestyramine (Questran), colestipol (Colestid) and lovastatin (Mevacor), the combination of drugs may result in greater lowering of cholesterol. However, when niacin is used with cholestyramine or colestipol, the drug may prevent niacin from being maximally effective, and when niacin is used with drugs such as lovastatin or gemfibrozil, there may be an increased risk of muscle degeneration. Combining neomycin with niacin may lower cholesterol levels more than niacin alone. Using niacin and nicotine together may increase some side effects such as flushing and dizziness. It is possible that birth control pills may enhance the activities of niacin, and lower niacin doses may be needed.
• Some drugs may reduce the effectiveness of niacin. Examples include antibiotics, isoniazid and pantothenic acid. Niacin may increase the effects and toxicity of some drugs such as diazepam (Valium), carbamazepine (Tegretol), valproate (Depakote, Depakene), griseofulvin, estrogens, progestins, testosterone and atracurium. Some of these possible drug interactions have been studied only in laboratory settings, and the significance in humans is not known.
• Niacin has been shown to increase blood sugar levels. Dosing adjustments may be needed for insulin or oral diabetes drugs. Niacin may also alter thyroid hormone levels, requiring larger doses of thyroid drugs. Vitamin B-6 (pyridoxine) and zinc sulfate may alter the metabolism of niacin, but the significance is unclear. Niacin may increase the risk of bleeding when used with anticoagulants (blood thinners) or antiplatelet drugs. Examples include warfarin (Coumadin), heparin and clopidogrel (Plavix). Some pain relievers may also increase the risk of bleeding if used with niacin. Examples include aspirin, ibuprofen (Motrin, Advil) and naproxen (Naprosyn, Aleve, Anaprox).

Interactions With Herbs And Dietary Supplements

Use of niacin with chromium polynicotinate, sitosterols and grape seed proanthocyanidin may cause greater cholesterol-lowering effects than any of the agents used alone. However, some research suggests that the use of niacin with antioxidants may slightly decrease the cardiovascular benefits of niacin. More studies are needed in this area. Because niacin alters thyroid hormone levels, it should be used carefully with other supplements that affect thyroid hormone levels, such as bladderwrack.

In theory, niacin may increase the risk of bleeding when taken with other products that are also believed to increase the risk of bleeding. Examples include Ginkgo biloba and garlic (Allium sativum). When niacin is used with herbs such as borage, chaparral, valerian or uva ursi, there may be an increased risk of liver toxicity. Niacin has been shown to increase blood sugar levels and may decrease the blood sugar-lowering properties of herbs such as bitter melon. Combining niacin with vitamin A and vitamin E may lower cholesterol levels more than niacin alone.

Dosing    

The doses listed below are based on scientific research, publications or traditional use. Because most herbs and supplements have not been thoroughly studied or monitored, safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients even within the same brand. Combination products often contain small amounts of each ingredient and may not be effective. Appropriate dosing should be discussed with a health care professional before starting therapy; always read the recommendations on a product's label. The dosing for unproven uses should be approached cautiously, because scientific information is limited in these areas.

The recommended daily dietary intake of niacin ranges from 16 to 35 milligrams. Taking niacin supplements with food may reduce the likelihood of stomach upset. Doses are usually started low and increased slowly to minimize flushing, although aspirin or ibuprofen may reduce the flushing adverse effect.

Adults (Aged 18 Or Older)

• By mouth: Doses used in studies for treating high cholesterol range from 300 to 3,000 milligrams of immediate-release (crystalline) niacin daily (divided into two or three doses) or from 500 to 2,000 milligrams of sustained-release niacin. Doses are usually started lower and increased gradually. When treating pellagra (niacin deficiency), doses between 50 and 1,000 milligrams daily have been used. Studies have used one to four grams of niacin daily for treating clogged arteries or heart disease or 200 to 3,000 milligrams of niacinamide daily to delay insulin dependence in diabetes.

Children (Younger Than 18): There are not enough scientific data to recommend niacin for use in children, and niacin is not recommended because of potential side effects. Note that there are concerns about the lack of evidence regarding treatment of childhood lipid disorders, including the long-term psychological and metabolic effects. At this time, diet alteration is acceptable first-line treatment, without the use of lipid-lowing drugs, until adulthood is reached.

Summary    

Vitamin B-3 is composed of niacin (nicotinic acid) and is a source of niacinamide. Niacin and niacinamide have been suggested as treatments for many conditions. There is scientific support for the use of niacin in lowering total cholesterol and low-density lipoprotein (LDL or "bad cholesterol") levels and in raising levels of high-density lipoprotein (HDL or "good cholesterol"). Niacin is also a well-established treatment for pellagra (niacin deficiency). There is some evidence that niacin may provide benefits for clogged arteries and may prevent heart disease. There is not enough scientific evidence to support the use of niacin or niacinamide for any other medical condition.

Niacin may cause many adverse effects, including flushing, headache, dizziness and itching. Niacin may also raise blood sugar levels, alter thyroid hormone levels, increase uric acid levels and cause liver damage. Therefore, niacin should be used carefully in people with diabetes, thyroid disease, gout and liver disease. It should also be avoided in pregnant or breast-feeding women and in children. Niacin may increase the risk of bleeding. Consult a health care professional immediately if you have any side effects.

The information in this monograph was prepared by the professional staff at Natural Standard, based on thorough systematic review of scientific evidence. The material was reviewed by the Faculty of the Harvard Medical School with final editing approved by Natural Standard.

Resources    

Selected Scientific Studies: Niacin

• Natural Standard reviewed more than 775 articles to prepare the professional monograph from which this version was created.

Some of the more recent studies are listed below:

Last updated July 14, 2005