Vitamin B3

• Vitamin B3 (niacin) is a water-soluble vitamin and refers to two compounds, nicotinic acid and nicotinamide.
• Important sources of niacin include beef, pork, wholegrain cereals, eggs and cow's milk.
  The niacin in meats is in the form of NAD and NADP and is more bioavailable.
  Foods that contain tryptophan, an amino acid the body coverts into niacin, include poultry, red meat, eggs and dairy products.
• Niacinamide is a component of nicotinamide adenine dinucleotide (NAD), also known as coenzyme I and nicotinamide adenine dinucleotide phosphate (NADP), also known as coenzyme II. These coenzymes are involved in many intracellular oxidation-reduction reactions.
  NAD is needed for non-redox adenosine diphosphate-ribose transfer reactions involved in DNA repair and calcium mobilisation.
• Niacin acts in conjunction with other B vitamins (B1, B2, B5, B6 and biotin) in the conversion of macronutrients (carbohydrates, fat and protein) into energy.
• It is rare for anyone in the developed world to have a B3 deficiency.
• In deficiency states, lack of nicotinamide can lead to fatigue, loss of appetite, pigmented rashes of the skin and oral ulcerations.
  More severe states of deficiency lead to pellagra that is characterized by cutaneous rashes, oral ulcerations, gastrointestinal difficulties and cognitive loss.
• Inadequate iron, riboflavin or vitamin B6 status decreases the conversion of tryptophan to niacin.
  The liver can synthesize niacin from the essential amino acid tryptophan. It takes 60 milligrams of tryptophan to produce just one milligram of niacin.
• The recommend daily allowance (RDA) for vitamin B3 is 6.5 mg per 1000 kcal.
• 1 mg niacin equivalent = 1mg niacin = 60 mg tryptophan.
• Niacin has a very high absorption rate through digestion and dosages up to 4 grams can be almost completely absorbed.
• Excessive dosages of vitamin B3 (over 75 milligrams) can lead to liver damage.
• The total body pool size of vitamin B3 is sufficient for 2-6 weeks.
• The tolerable upper level (UL) is 900 mg nicotinamide per day.
• The tolerable upper level (UL) is 10 mg nicotinic acid per day.
• Vitamin B3 is available in 3 supplement forms: niacinamide, niacin and inositol hexaniacinate.

Scientific studies on the relationship between vitamin B3 and disease prevention:
A review of articles of randomized, placebo-controlled double blind clinical trials (RCTs) will answer the following question:
"Do taking dietary supplements make sense?" Yes for a positive conclusion and no for a negative conclusion.

A review of articles of cohort studies or case-control studies will answer the following question:
"Should I change my diet?".

1. Niacin supplementation reduces LDL cholesterol levels in patients with type 2 diabetes mellitus
2. Vitamin B3 supplementation increases good cholesterol in patients with type 2 diabetes mellitus