(Niacin, niacinamide, nicotinamide, inositol hexaniacinate)

Vitamin B3 is required for proper function of more than 50 enzymes. Without it, your body would not be able to release energy or make fats from carbohydrates. Vitamin B3 is also used to make sex hormones and other important chemical signal molecules.

Vitamin B3 is needed for healthy skin and proper circulation of the blood throughout the body. As with other B vitamins, it also aids in proper functioning of the nervous system and in the metabolism of proteins, fats and carbohydrates. The secretion of bile and stomach acids requires niacin. Niacin lowers cholesterol and helps with the synthesis of hormones, including estrogen and testosterone. It is often used to enhance memory.

Similar to riboflavin, vitamin B3 is used in energy production by the cell. It is an integral part of nicotinamide adenine dinucleotide phosphate and nicotinamide adenine dinucleotide. These enzymes are also used to transfer hydrogen ions (which are supplied by sugars and fatty acids in the diet)to the cytochrome and hydrogen ion transfer systems to supply energy to the body.

Tryptophan metabolism is intrinsically linked to niacin (niacin may also be synthesized from dietary tryptophan if the diet is low in niacin and adequate tryptophan is available). In cats, however, one of the intermediate compounds formed during tryptophan metabolism to niacin is quickly utilized by another pathway; therefore, cats cannot convert tryptophan to niacin. Thus cats, unlike dogs, have a strict dietary requirement for niacin.

Vitamin B3 comes in two principal forms niacin (nicotinic acid) and niacinamide (nicotinamide). When taken in low doses for nutritional purposes, they are essentially identical. However, each has its own particular effects when taken in high doses. High-dose niacin is principally used for lowering cholesterol. High-dose niacinamide may be helpful in presenting type I (childhood-onset) diabetes and reducing symptoms of osteoarthritis in people. However, these are concerns regarding liver inflammation when any form of niacin is taken at high dosages.

Scientific Evidence
There is no question that niacin (but not niacinamide) can significantly lower total cholesterol and LDL cholesterol and raise HDL cholesterol in people. However, unpleasant flushing reaction and the risk of liver inflammation have kept niacin from being widely used. According to numerous studies, niacin can lower cholesterol and LDL (“bad”) cholesterol by 15 to 25 percent, lower triglycerides by two to 50 percent, and raise HDL (“good”) cholesterol by 15 to 25 percent. Furthermore, longterm use of niacin has been shown to significantly reduce death rates from cardiovascular disease.

Intriguing evidence suggests that regular use of niacinamide (but not niacin) may help prevent diabetes in children at special risk of developing it. Risk can be determined by measuring the ratio of antibodies to islet cells (ICA antibody test). Niacinamide may improve blood sugar control in both children and adults who already have diabetes.

Exciting evidence from a huge study conducted in New Zealand suggests that niacinamide can prevent high-risk children from developing diabetes. In this study more than 20,000 children were screened for diabetes risk by measuring ICA antibodies. It turned out that 185 of these children had detectable levels. About 170 of these children were then given niacinamide for seven years (not all parents agreed to give their children niacinamide or stay in the study for that long). About 10,000 other children were not screened, but were followed to see whether they developed diabetes.

The results were impressive. In the group in which children were screened and given niacinamide if they were positive for ICA antibodies, the incidence of diabetes was reduced by as much as 60 percent. These findings suggest that niacinamide is a very effective treatment for preventing diabetes. (It also shows that tests for ICA antibodies can very accurately identify children at risk for diabetes.)

At present, an enormous-scale, long-term trial called European Nicotinamide Diabetes Intervention Trial is being conducted to definitely determine whether regular use of niacinamide can prevent diabetes.

If a child has just developed diabetes, niacinamide may prolong what is called the honeymoon period. This is in the interval in which the pancreas can still make insulin, and insulin needs are low. A recent study suggests that niacinamide may also improve blood sugar control in type II (adult-onset) diabetes, but it did not use a double-bind design.

According to several good-size, double-bind studies involving a total of over 500 individuals, a special form of niacin, inositol hexaniacinate, may be able to improve walking distance in intermittent claudication (severe leg cramps caused by hardening of the arteries). For example, in one study, 120 individuals were given either placebo or 2 g of inositol hexaniacinate daily. Over a period of three months, walking distance improved significantly in the treated group. (Other treatments that may help intermittent claudication include carnitine and ginko.)

Preliminary evidence (one small double-bind study) suggests that insoitol hexaniacinate niacinamide may be able to reduce symptoms of Raynaud’s phenomenon as well. This condition includes a response to cold, usually most severely in the hands. The dosage used in he study was 4 g daily, again a dosage high enough for liver inflammation to be a real possibility.

Preliminary evidence suggests that niacinamide may be able to reduce symptoms of osteoarthritis. There is some evidence that niacinamide may provide some benefits for those with osteoarthritis. In a double-bind study, 72 individuals with arthritis were given either 3,000 mg daily of niacinamide (in five equal doses) or placebo for 12 weeks. The results showed that treated patients experienced a 20 percent improvement in symptoms, whereas those given placebo worsened by 10 percent. However, at this dose, liver inflammation is a concern that must be taken seriously.

Very weak evidence suggests one of the several forms of niacin may be helpful in bursitis, cataracts, and pregnancy.

Therapeutic Uses
Niacin was discovered to be the specific chemical that cured black tongue (pellagra) in dogs fed niacin-deficient diets. Niacin deficiency (pellagra) causes dermatitis, diarrhea, dementia and death.

Niacinamide has been recommended for the treatment of several disorders in pets, including discoid lupus erythematosus and pemphigus erythematosus in dogs. When combined with tetracycline, niacinamide (at a dosage of 500 mg of tetracycline and 500 mg of nacinamide per dog given every eight hours for dogs weighing more than 10 kg) has been found to show an excellent response in 25 to 65 percent of cases. While no studies support the use of niacinamide for dogs with atopic dermatitis, since niacinamide works by inhibiting antigen-IgE-induced histamine release, it may be an option for atopic dogs.

Sources
Good food sources of niacin are seeds, yeast, bran, peanuts (especially with skins), wild rice, brown rice, whole wheat, barley, almonds, liver, brewer’s yeast, broccoli, carrots, cheese, eggs, fish, milk, pork, potatoes, and peas. Tryptophan is found in protein foods (meat, poultry, dairy products, and fish). Turkey and milk are particularly excellent sources of tryptophan. Other sources include green alfalfa and the herbs catnip, cayenne, chamomile, chickweed, licorice, mullein, nettle, peppermint, raspberry leaf, red clover, rose hips, slippery elm, and yellow dock.

Dosages
The AAFCO recommends 11.4 mg/kg of niacin daily for dogs and 60 mg/kg of niacin for cats.

Safety Issues
In people, when taken at a dosage of more than 100 mg daily, niacin frequently causes annoying skin flushing, especially in the face. This reaction may be accompanied by stomach distress, itching and headache. In studies, as many as 43 percent of individuals taking niacin quit because of the unpleasant side effects.

A more dangerous effect is liver inflammation. Although most commonly seen with slow-release niacin, it can occur with any type of niacin,when taken at a daily dose of more than 500 mg. Regular blood tests to evaluate liver function are therefore mandatory when using high-dose (or niacinamide or inositol hexaniacinate). This side effect almost always goes away when niacin is stopped. People with liver disease, ulcers (presently or in the past), gout, or diabetes should not take high-dose niacin except on medical advice.

Maximum safe dosages for young children and pregnant or nursing women have not been established. Pets are not routinely treated with niacin. However, similar precautions are probably warranted if your pet is prescribed niacin.

As in the case in human medicine, if your pet is taking cholestrol-lowering drugs in the statin family, he should probably not take additional niacin. Pets taking older choslestrol-lowering drugs such as cholestyramine or colestipol should take niacin at a different time of day to avoid absorption problems based on the recommendation in human medicine. Pets taking the antituberculosis drug isoniazid may need extra niacin. However, because niacin can interfere with INH, doctor supervision is necessary.

Shawn Messonnier, DVM Dr. Messonnier, a 1987 graduate of Texas A& M College of Veterinary Medicine, opened Paws & Claws Animal Hospital in 1991. His special interests include exotic pets, dermatology, and animal behavior. Dr. Messonnier is a well-known speaker and author. Visit: www.petcarenaturally.com.

Vitamin C is a water soluble vitamin that is required by people and some animals. Humans and certain animals (such as guinea pigs and monkeys) lack the enzyme L-gulonolactone oxidase needed for the formation of vitamin C. Dogs and cats possess this enzyme and can therefore synthesize vitamin C. As such, dogs and cats do not have a specific dietary requirement for this vitamin. Many doctors, however will supplement with vitamin C during times of stress and illness (as larger amounts of vitamin C may be required during these times.)

Ascorbic acid is a term often used interchangeably with vitamin C. While ascorbic acid (as well as ascorbate and other terms) is often used synonymously with vitamin C, this is not technically correct. Ascorbic acid (discovered in 1928, when Albert Szent-Gyorgyi isolated the active ingredient in fruits and called the “anti-scorbutic principle”) is the antioxidant fraction of vitamin C. Simply supplementing ascorbic acid is not the same as supplying vitamin C. Holistic veterinarians usually prefer natural vitamin C supplementation when indicated, although studies using the complementary therapy called orthomolecular medicine have shown benefit to using ascorbate in helping pets with a variety of medical disorders. A novel product called Ester-C has also shown benefit in pets.

Vitamin C functions as an antioxidant and free radical scavenger, is used for normal repair of tissue, is required for adrenal gland function, is used for collagen synthesis, and is needed for maintaining healthy gums. It is needed for metabolism of several B vitamins, including folic acid and the amino acids tyrosine and phenylalanine. Vitamin C is needed for norepinephrine (a nerve transmitter) synthesis as well as for cholesterol synthesis.

Therapeutic Uses
This vitamin assists in providing protection against cancer and enhances immunity. Hemoglobin synthesis requires vitamin C; deficiency can cause anemia.

Because vitamin C is so vital for the synthesis of the connective tissue collagen, which is an integral part of cartilage, it is often prescribed for pets with arthritis (and various forms of vitamin C or ascorbate acid are often included in various supplements for pets with arthritis.)

To have normal collagen metabolism, vitamin C is required for the conversion of proline to hydroxyproline and for the conversion of lysine to hydroxylysine. These reactions take place after proline and lysine are incorporated into the connective tissue.

Vitamin C also protects against unnecessary blood clotting and bruising and aids in healing of wounds; vitamin C deficiency causes slow scar formation.

Ascorbic acid is a precursor of oxalate. It has been suggested that additional ascorbic acid should not be feed to pets prone to oxalate bladder stones. However, at least in people, there is no evidence that high levels of ascorbic acid actually increase oxalate production.

Vitamin C appears to work synergistically as an antioxidant with vitamin E. Vitamin C appears to attack free radicals, those chemicals produced as a by-product of cell metabolism, in cellular fluids, whereas vitamin E attacks the free radicals in the cell membranes.

In people, vitamin C has been recommended for numerous conditions, including colds, cataracts, macular degeneration, cancer prevention and treatment, heart disease prevention, hypertension, asthma, low sperm count, bedsores, Alzheimer’s disease, diabetes, hepatitis, herpes, insomnia, osteoarthritis, Parkinson’s disease periodontal disease, preeclampsia, rheumatoid arthritis, ulcers, allergies, general antioxidant, bladder infections, menopausal symptoms, migraine headaches and nausea.

Ascorbic acid scavenges nitrates, which can reduce nitrosamine- induced cancers.

There is some evidence that supports using vitamin C supplement to help colds, slightly improve asthma and reduce the risk of macular degeneration and cataracts.

In people, vitamin C deficiency cause scurvy with the clinical signs of swollen, painful joints, abnormal wound healing, bleeding gums, and pinpoint hemorrhages under the skin. Vitamin C deficiency, while common in non-human primates (monkeys) and guinea pigs, does not occur in dogs and cats.

Scientific Evidence
Regular use of vitamin C may reduce the risk of cataracts, probably by fighting free radicals that damage the lens of the eye. In an observational study or 50,800 nurses followed for 8 years, it was found that people who used vitamin C supplements for more than 10 years had a 45 percent lower rate of cataract development. However, unlike the case of other supplements, diets high in vitamin C were not found to be protective; only supplemental vitamin C made a difference. This is the opposite of what was found with vitamin C in the prevention of other disease, such as cancer.

It had been suggested that vitamin C may be particularly useful against cataracts in people with diabetes, because of its influence on sorbitol, a sugar-like substance that tends to accumulate in the cells of diabetics. Excess sorbitol is believed to play a role in the development of diabetes-related cataracts, and vitamin C appears to help reduce sorbitol buildup.

Vitamin C levels in the blood have been found to be low in people with diabetes. When vitamin C levels are adequate, the regulation of insulin improved, as vitamin C has been shown to enhance insulin action glucose and lipid metabolism. Therefore, vitamin C supplementation may benefit both insulin-dependent and non-insulin diabetics. It is unknown if this is the case in diabetic pets, although vitamin C has been recommended for pets with diabetes.

There is also good evidence for using ascorbate for people with gingivitis. Evidence for its effectiveness in treating their conditions is highly preliminary at best.

In people, aspirin, other inflammatory drugs, corticosteroids, and tetracycline-family antibiotics can lower body levels of vitamin C. The same may be true of pets, vitamin C given to pets treated with the medications mentioned above is not harmful and might be helpful.

Pets are often treated with additional vitamin C or ascorbate compounds for various illnesses. Both intravenous and oral supplementation are used, although controlled studies are lacking showing the effectiveness of giving vitamin C or ascorbate compounds for most conditions.

Sources
Citrus fruits, green vegetables, berries, broccoli, Brussels sprouts, collard greens, spinach, chard, turnip greens, red chili peppers, sweet potatoes, kale, parsley, watercress, cauliflower, cabbage and strawberries are good sources of vitamin C, as are green foods, alfalfa, herbs, rose hips dandelion, fennel and slippery elm.

Safety Issues
In pets and in people, high-doses of vitamin C may cause diarrhea. There have been warnings that long-term vitamin C treatment can cause kidney stones, but in a large-scale study the people who took the most vitamin C (over 1,500 mg daily) actually had a lower risk of kidney stones than those taking the least amounts. Nonetheless, people with a history of kidney stones and those with kidney failure who have a defect in vitamin C or oxalate metabolism should probably restrict vitamin C intake to approximately 200 mg daily. While there is no evidence that stone formation increases people or pets supplemented use with vitamin C, talk with your veterinarian before adding extra vitamin C if your pet is prone to urinary stones.

Vitamin C may also reduce the blood-thinning effects of Coumadin (warfarin) and heparin.

Vitamin C may increase the blood levels of some drugs, such as aspirin and other salicylates.

Always consult with your veterinarian before adding vitamins and supplements to your pet’s diet.