1. Significance and sources of niacin
Domina Petric, MD

2. Significance of niacin
Niacin is required for the biosynthesis of the pyridine nucleotides NAD(H) and NADP(H): key roles in virtually all aspects of metabolism.
Niacin deficiency was prevalent among people who relied on maize (corn) as their major food staple.
11/21/2018
Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc

3. Significance of niacin
Niacin deficiency more frequently results from poor bioavailability rather than scarcity per se.
11/21/2018
Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc

4. Distribution in foods
Niacin occurs in greatest quantities in brewers’ yeasts and meats, but significant amounts are also found in many other foods.
The vitamin is distributed unevenly in grains, being present mostly in the bran fractions.
11/21/2018
Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc

5. Distribution in foods Niacin occurs predominantly in bound forms.
In plants: protein-bound nicotinic acid (NA).
In animal tissues: nicotinamide (NAm) in nicotinamide-adenine dinucleotide (NADH) and nicotinamide-adenine dinucleotide phosphate (NADPH).
11/21/2018
Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc

6. Diary products Diary product Niacin mg/100 g Milk 0,2 Yogurt 0,1
Cheeses
1,2
11/21/2018
Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc

7. Meats Meat Niacin mg/100 g Beef 4,6 Chicken 4,7-14,7 Lamb 4,5 Pork
0,8-5,6
Turkey
8,0
Calf heart
7,5
Calf kidney
6,4
Herring
3,6
Cod
2,2
Flounder
2,5
Haddock
3,0
Tuna
13,3
11/21/2018
Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc

8. Cereals Cereal Niacin mg/100 g Barley 3,1 Buckwheat 4,4 Cornmeal
1,4-2,9
Polished rice
1,6
Unpolished rice
4,7
Rye
0,9-1,6
Whole grain wheat
3,4-6,5
Wheat bran
8,6-33,4
11/21/2018
Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc

9. Vegetables Vegetable Niacin mg/100 g Asparagus 1,5 Beans 0,5-2,4
Broccoli
0,9
Brussels sprouts
Cabbage
0,3
Carrots
0,6
Cauliflower
0,7
Celery
Corn
1,7
Kale
2,1
Lentils
2,0
11/21/2018
Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc

10. Vegetables Vegetable Niacin mg/100 g Onions 0,2 Peas 0,9-25 Peppers
1,7-4,4
Potatoes
1,5
Soy beans
1,4
Spinach
0,6
Tomatoes
0,7
11/21/2018
Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc

11. Fruits Fruit Niacin mg/100 g Apples 0,6 Bananas 0,7 Grapefruit 0,2
Oranges
0,4
Peaches
1,0
Strawberries
11/21/2018
Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc

12. Nuts and other Nut Niacin mg/100 g Most nuts 0,6-1,8 Peanuts 17,2
Eggs
0,1
Mushrooms
4,2
Yeast
50,1
11/21/2018
Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc

13. Stability
Niacin in foods is very stable to storage and to normal means of food preparation and cooking (moist heat).
11/21/2018
Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc

14. Bioavailability
Niacin is found in many types of foods in forms from which it is not released on digestion, thereby rendering it unavailable to the eater.
In grains, niacin is present in covalently bound complexes with small peptides and carbohydrates, collectively referred to as niacytin.
11/21/2018
Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc

15. The esterified niacin in these complexes is not normally available.
Bioavailability
The esterified niacin in these complexes is not normally available.
Its bioavailability can be improved substantially by treatment with base to effect the alkaline hydrolysis of those esters.
11/21/2018
Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc

16. Importance of dietary tryptophan
A substantial amount of niacin can be synthesized from the indispensable amino acid tryptophan.
The niacin adequacy of diets involves not only the level of the preformed vitamin, but also that of its potential precursor tryptophan.
11/21/2018
Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc

17. Literature
Combs GF. The Vitamins. Fundamental Aspects in Nutrition and Health. Elsevier Inc
11/21/2018