**Mechanism of Action and Health Benefits**:
– Nicotinamide adenine dinucleotide (NAD) and NADP are essential for DNA repair, calcium mobilization, glycolysis, and the Krebs cycle.
– NAD is converted from vitamin B within the body and is critical for human metabolism.
– Niacin and nicotinamide are components of coenzymes NAD and NADP.
– Vitamin B supports energy production, brain function, red blood cell formation, metabolism, and the nervous system.
– Niacin and nicotinic acid can lower cholesterol, support heart health, improve skin conditions, aid in energy conversion, and maintain proper nervous system function.
**Vitamin Deficiency and Health Conditions**:
– Severe vitamin B deficiency causes pellagra, leading to symptoms like diarrhea, dermatitis, mouth inflammation, delirium, and dementia.
– Niacin deficiency is rare in developed countries but can result from poverty and malnutrition.
– Hartnup disease and Carcinoid syndrome are conditions leading to niacin deficiency.
– WHO recommends niacinamide for treating niacin deficiency, which can manifest as dementia, dermatitis, and sensitivity to sunlight.
**Sources and Preparation of Vitamin B**:
– Niacin is found in fortified foods, meat, fish, nuts, and seeds.
– Niacin can be synthesized from tryptophan, and pellagra can be treated with niacin supplements.
– Proper food handling and cooking methods can affect the bioavailability and retention of niacin in food.
– Fortification of wheat, maize, and rice with niacin aims to address nutrient deficiencies in populations.
– Vegetarian and vegan diets can include nutritional yeast, peanuts, and fortified foods for niacin intake.
**Measuring Vitamin Status and Dietary Guidelines**:
– Plasma concentrations of niacin are unreliable markers, while urinary excretion of N1-methyl-nicotinamide and erythrocyte NAD concentrations can indicate niacin status.
– Recommended Dietary Allowances for niacin are set by the U.S. Institute of Medicine, and the European Food Safety Authority uses Population Reference Intake.
– Various organizations provide dietary reference intakes for niacin, with different nutrient reference values across regions.
– The U.S. FDA regulates daily values on nutrition labels, and the EFSA sets tolerable upper intake levels for vitamins and minerals.
– The EFSA Panel on Dietetic Products establishes dietary reference values for the EU population.
**Toxicity, Supplementation, and Forms of Vitamin B3**:
– Excessive niacin intake can lead to toxicity, with skin flushing occurring at doses as low as 30mg.
– Daily limit for vitamin B is set at 35mg, with liver toxicity possible at doses above 2 grams/day.
– Niacin supplements range from 100 to 1000mg per serving, with health claims allowed by the US FDA, but caution advised by the AHA.
– Forms of vitamin B3 include nicotinic acid, niacinamide, and nicotinamide riboside, which play crucial roles in NAD+ synthesis.
– Niacin is essential for genomic stability and can have severe reactions like fulminant hepatitis at high doses.
B vitamins are a class of water-soluble vitamins that play important roles in cell metabolism and synthesis of red blood cells. They are a chemically diverse class of compounds; some contain sulfur and B12 contains cobalt. Dietary supplements containing all eight are referred to as a vitamin B complex. Individual B vitamins are referred to by B-number or by chemical name, such as B1 for thiamine, B2 for riboflavin, and B3 for niacin, while some are more commonly recognized by name than by number, such as pantothenic acid (B5), biotin (B7), and folate (B9).
Each B vitamin is either a cofactor (generally a coenzyme) for key metabolic processes or is a precursor needed to make one.