Niacin is an essential vitamin that is required for many metabolic processes. It is found predominantly in foods in bound forms that have poor bioavailability. Niacin deficiency was historically more common when diets relied heavily on maize. While niacin is widely distributed in foods like meats, cereals, vegetables and nuts, the amount of bioavailable niacin varies depending on food processing and cooking methods. Tryptophan can also be converted to niacin in the body.

1. Domina Petric, MD
Significance and sources of niacin

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.
4/16/2018
Combs GF. The Vitamins. Fundamental Aspects
in Nutrition and Health. Elsevier Inc. 2008.
2

3. Significance of niacin
Niacin deficiency more
frequently results from
poor bioavailability rather
than scarcity per se.
4/16/2018
Combs GF. The Vitamins. Fundamental Aspects
in Nutrition and Health. Elsevier Inc. 2008.
3

4. Distribution in foods
4/16/2018
Combs GF. The Vitamins. Fundamental Aspects
in Nutrition and Health. Elsevier Inc. 2008.
4

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).
4/16/2018
Combs GF. The Vitamins. Fundamental Aspects
in Nutrition and Health. Elsevier Inc. 2008.
5

6. Diary products
Diary product Niacin mg/100 g
Milk 0,2
Yogurt 0,1
Cheeses 1,2
4/16/2018
Combs GF. The Vitamins. Fundamental Aspects
in Nutrition and Health. Elsevier Inc. 2008.
6

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
4/16/2018
Combs GF. The Vitamins. Fundamental Aspects
in Nutrition and Health. Elsevier Inc. 2008.
7

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
4/16/2018
Combs GF. The Vitamins. Fundamental Aspects
in Nutrition and Health. Elsevier Inc. 2008.
8

9. Vegetables
Vegetable Niacin mg/100 g
Asparagus 1,5
Beans 0,5-2,4
Broccoli 0,9
Brussels sprouts 0,9
Cabbage 0,3
Carrots 0,6
Cauliflower 0,7
Celery 0,3
Corn 1,7
Kale 2,1
Lentils 2,0
4/16/2018
Combs GF. The Vitamins. Fundamental Aspects
in Nutrition and Health. Elsevier Inc. 2008.
9

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
4/16/2018
Combs GF. The Vitamins. Fundamental Aspects
in Nutrition and Health. Elsevier Inc. 2008.
10

11. Fruits
Fruit Niacin mg/100 g
Apples 0,6
Bananas 0,7
Grapefruit 0,2
Oranges 0,4
Peaches 1,0
Strawberries 0,6
4/16/2018
Combs GF. The Vitamins. Fundamental Aspects
in Nutrition and Health. Elsevier Inc. 2008.
11

12. Nuts and other
Nut Niacin mg/100 g
Most nuts 0,6-1,8
Peanuts 17,2
4/16/2018
Combs GF. The Vitamins. Fundamental Aspects
in Nutrition and Health. Elsevier Inc. 2008.
12
Other Niacin mg/100 g
Eggs 0,1
Mushrooms 4,2
Yeast 50,1

13. Stability
Niacin in foods is very stable
to storage and to normal
means of food preparation
and cooking (moist heat).
4/16/2018
Combs GF. The Vitamins. Fundamental Aspects
in Nutrition and Health. Elsevier Inc. 2008.
13

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.
4/16/2018
Combs GF. The Vitamins. Fundamental Aspects
in Nutrition and Health. Elsevier Inc. 2008.
14

15. 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.
4/16/2018
Combs GF. The Vitamins. Fundamental Aspects
in Nutrition and Health. Elsevier Inc. 2008.
15

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.
4/16/2018
Combs GF. The Vitamins. Fundamental Aspects
in Nutrition and Health. Elsevier Inc. 2008.
16

17. • Combs GF. The Vitamins. Fundamental Aspects in
Nutrition and Health. Elsevier Inc. 2008.
Literature
4/16/2018 17