Nutrition Guide

Panthenol is the alcohol analog of pantothenic acid (vitamin B5), and is thus the provitamin of B5. In organisms it is quickly oxidized to pantothenate. Panthenol is a highly viscous transparent liquid at room temperature, but salts of pantothenic acid (for example sodium pantothenate) are powders (typically white). It is well soluble in water, alcohol and propylene glycol, soluble in ether and chloroform, and slightly soluble in glycerin.

Panthenol comes in two enantiomers, D and L. Only D-panthenol (dexpanthenol) is biologically active, however both forms have moisturizing properties. For cosmetic use, panthenol comes either in D form, or as a racemic mixture of D and L (DL-panthenol).

Panthenol’s expanded chemical formula is: HO-CH2-C(CH3)2-CH(OH)-CONH-CH2CH2CH2-OH.

Niacin is essentially found in meat, wheat germ, dairy products, and yeast.

Animal products:
liver, heart and kidney
chicken
beef
fish: tuna, salmon
milk
eggs

Fruits and vegetables:
avocados
dates
tomatoes
leaf vegetables
broccoli
carrots
sweet potatoes
asparagus

Seeds:
nuts
whole grain products
legumes
saltbush seeds

Fungi:
mushrooms
brewer’s yeast

The receptor for niacin is a G protein-coupled receptor called HM74A.[29] It couples to Gi alpha subunit.[30]

The liver can synthesize niacin from the essential amino acid tryptophan, requiring 60 mg of tryptophan to make one mg of niacin.[28]

The 5-membered aromatic heterocycle of tryptophan is cleaved and rearranged with the alpha amino group of tryptophan into the 6-membered aromatic heterocycle of niacin.

One popular form of dietary supplement is inositol hexanicotinate, usually sold as “flush-free” or “no-flush” niacin (although those terms are also used for regular sustained-release.) While this form of niacin does not cause the flushing associated with the nicotinic acid form, it is not pharmacologically equivalent in its positive effect.[27] Prescription grade niacin is available and is proven to reduce cholesterol. Thus far there is not enough evidence to recommend inositol hexanicotinate to treat dyslipidemia. Niacin when taken in slowly increasing doses will cause far less flushing.

People taking pharmacological doses of niacin (1.5 - 6 g per day) often experience side-effects that can include dermatological complaints such as facial flushing and itching, dry skin, skin rashes including acanthosis nigricans. Gastrointestinal complaints, such as dyspepsia (indigestion) and liver toxicity (fulminant hepatic failure) have also been reported. Also reported include hyperglycemia, cardiac arrhythmias, birth defects, and orthostasis.[20]

Facial flushing is the most commonly reported side effect.[21] It lasts for about 15 to 30 minutes, and is sometimes accompanied by a prickly or itching sensation, particularly in areas covered by clothing. This effect is mediated by prostaglandin and can be blocked by taking 300 mg of aspirin half an hour before taking niacin, or by taking one tablet of ibuprofen per day. Taking the niacin with meals also helps reduce this side effect. After 1 to 2 weeks of a stable dose, most patients no longer flush.[citation needed] Slow- or “sustained”-release forms of niacin have been developed to lessen these side-effects.[14][22] One study showed the incidence of flushing was significantly lower with a sustained release formulation[23] though doses above 2 g per day have been associated with liver damage, particularly with slow-release formulations.[20]

High-dose niacin may also elevate blood sugar, thereby worsening diabetes mellitus.[20] Hyperuricemia is another side-effect of taking high-dose niacin, and may exacerbate gout.[24] Niacin at doses used in lowering cholesterol has been associated with birth defects in laboratory animals, with possible consequences for infant development in pregnant women.[20]

Niacin at extremely high doses can have life-threatening acute toxic reactions.[25] Extremely high doses of niacin can also cause niacin maculopathy, a thickening of the macula and retina which leads to blurred vision and blindness. This maculopathy is reversible after stopping niacin intake.[26

Niacin is sometimes consumed in large quantities by people who wish to fool drug screening tests, particularly for lipid soluble drugs such as marijuana.[18] It is believed to “promote metabolism” of the drug and cause it to be “flushed out”. Scientific studies have shown it does not affect drug screenings, but can pose a risk of overdose, causing arrhythmias, metabolic acidosis, hyperglycemia, and other serious problems.[19]

A fat-soluble derivative of niacin has been developed that efficiently penetrates the skin. This form of niacin has been shown to improve a variety of skin conditions in a number of controlled clinical trials.[17][unreliable source?]

The argument that niacin does not provide any benefits at doses above the RDA has been decisively disproven.[citation needed] There are two decisively proven uses of pharmacological doses of niacin. These are for heart disease and skin conditions. Extensive evidence combining known biochemical functions of vitamin B3, controlled trials, and clinical observations indicate that doses of niacin above the RDA speed wound healing[citation needed] and help the immune system fight off viral infections.[12][unreliable source?] The available evidence supports the hypothesis that response is proportional to dose well past the side effect threshold.[citation needed] The side effect threshold for niacin varies dramatically from person to person, ranging from between 30 and 300 mg for the majority of the population.

Niacin, prescribed in doses between 1000 and 2000 mg two to three times daily, [13] blocks the breakdown of fats in adipose tissue, more specifically the very-low-density lipoprotein (VLDL), precursor of low-density lipoprotein (LDL) or “bad” cholesterol. Because niacin blocks breakdown of fats, it causes a decrease in free fatty acids in the blood and, as a consequence, decreased secretion of VLDL and cholesterol by the liver.[14]

By lowering VLDL levels, niacin also increases the level of high-density lipoprotein (HDL) or “good” cholesterol in blood, and therefore it is sometimes prescribed for patients with low HDL, who are also at high risk of a heart attack.[15][16]

As of August 2008, a combination of niacin with laropiprant is tested in a clinical trial. Laropiprant reduces facial flushes induced by niacin.