ROLE OF IRON IN HUMAN HEALTHArun Malik and Hariom Yadav

NATIONAL AGRI-FOOD BIOTECHNOLOGY INSTITUTE, MOHALI , PUNJAB, INDIAEmail: yadavhariom@gmail.com

WHY DO WE NEED IRON

Iron is a mineral found in every cell in the body.

It is vital for both physical health and mental well-being.

Iron has three main functions :

carrying oxygen from the lungs to the rest of the body. maintaining a healthy immune system. (Body protects itself from antigens, which includes virus, bacteria and foreign substances that make sick)

aiding energy production. (Iron is constituent of several enzymes including : iron catalase, peroxidase, and cytochrome enzymes)

INSUFFICIENT DIETARY IRON CAN RESULT IN IRON DEFICIENCY

fatiguelethargymore frequent infectionsreduced resistance to coldimpaired learningHypoferrimia

TYPES OF IRON

There are two types of iron in food:

Heme iron, derived from the hemoglobin and myoglobin found in meat tissue Non-heme iron, derived mainly from cereals, legumes, fruit and vegetables.

HEME IRON Heme iron is found only in animal foods. The iron in meat is approximately 40% heme iron and 60% non-heme iron. Plant foods do not contain any heme iron .

Heme iron is well absorbed and relatively unaffected by other factors .

It is influenced to some extent by the body’s iron stores. The average absorption of heme iron in meat is about 25%.

NON-HEME IRON

Non-heme iron is found in plant foods.

It is not as well absorbed as heme iron and is affected by both the iron status of an individual, and components in foods eaten at the same time.

Absorption of non-heme iron can vary from under 1% in an individual with replete stores to 20% in an individual with depleted iron stores .

Generally non-heme iron absorption is less than 5%.

VITAMIN C IMPROVE NON-HAEM IRON ABSORPTION

Vitamin C can increase the absorption of non-haem iron by two to three times. There is a dose-related effect; the more vitamin C in a meal, the greater the iron absorption - up to a limit of around 100mg vitamin C .

Vitamin C is found in fruit and vegetables. Both heat and air reduce vitamin C content, so care should be taken when cooking and storing fruit and vegetables.

FACTORS AFFECTING NON-HAEM IRON ABSORPTION

IMPROVE ABSORPTION INHIBIT ABSORPTION

CAULIFLOWER TANNINS IN TEA

TOMATOES DIETARY FIBRE

KIWIFRUIT SOY PROTEINS

MEAT, FISH, POULTRY PHYTATES IN WHOLEGRAINS

TAMARILLOS POLYPHENOLS

CITRUS FRUIT (ORANGES, GRAPES) OXALATE

IRON SUPPLEMENTS Iron supplements should only be used when advised by a dietitian or prescribed by a medical practitioner for diagnosed iron deficiency.

Iron supplements should be used cautiously as they may interfere with the absorption of other nutrients such as zinc and calcium.

IRON ABSORPTION IN HUMAN BODY

HEME IRON UPTAKEHEME IRON

HEME IRON TRANSPORT

ENDOCYTOSIS FERROUS IRON

LIBERATED WITH IN ENDOSOME

NON-HEME IRON UPTAKEFERRIC IRON

REDUCED BY ASCORBIC

ACID

FERROUS IRONINCLUDE

DUODENAL CYTOCHROME

B

TRANSFERRIN

FERROPORTIN HEPHAESTIN

HEPCIDIN REGULATES IRON ABSORPTION

Hepcidin is 25 amino-acid peptide hormone. Hepcidin is synthesized by hepatocytes. Hepcidin binds to ferroportin1 and causes

its internalization and degradation thereby

decrease iron transfer to blood. Hepcidin function to regulate(inhibit)

iron transport across gut mucosa there by

preventing normal iron level.

HOW HEPCIDIN REGULATES IRON ABSORPTION

Hepcidin regulation by Inflammation

IL-6 a prominent inducer of hepcidin, through STAT-3 dependent transcriptional mechanism.◦ Other cytokines may also induce hepcidin independent of IL-6.

Macrophage also express hepcidin in response to

micobial stimulation.◦ Hepcidin may function in autocrine manner to degrade macrophage

ferroportin,

causing local retention of iron in macrophages.

EFFECT OF MUTATION OF SPECIFIC PROTEINS

IRON OVERLOAD IRON DEFICIENCY

Hypotransferrinanemia - recessive TMPRSS6 mutation - IRIDA

HFE gene mutation

Ferroportin mutation – autosomal dominant

Hepcidin mutations

Hemojuvelin mutations

H ferritin mutation - dominant

HUMAN DISEASE ASSOCIATED WITH IRON

CARDIOVASCULAR DISEASE

Heme iron are associated with cardiovascular diseases(CVD) risk.

Such as saturated fats or other dietary and

lifestyle factors associated with meat intake.

HEMOCHROMATOSIS PROTEIN HFE

Hereditary hemochromatosis is inherited disorder that results from an excess accumulation of iron in many organs which is manifested by liver cirrhosis, cardiomyopathy, diabetes mellitus, arthritis, skin pigmentation and if left untreated death.

The gene responsible for hereditary hemochromatosis is closely linked to locus for the human leukocyte antigens and has been identified as major histocompatibility complex-encoded class-1 like HFE.

Hereditary hemochromatosis is more prevalent than other inherited diseases such as cystic fibrosis, sickle cell anemia, phenylketonuria and Tay-Sachs disease.

THE FRIEDRICH’S ATAXIA PROTEIN

Farataxin is mitochondrial protein which involved in mitochondrial iron homeostasis.

Farataxin deficiency is due to hyper-expansion of polymorphic GAA trinucleotide repeat which inhibits transcription and falls in levels of mature faratxin mRNA.

Farataxin deficiency in patients leads to develop Friedrich’s ataxia which is a progressive neurological disorder and cardiomyopathy and finally leads to death.

MELANOTRANSFERRIN• Melanotransferrin reported to expressed in amyloid

plaques in brain of patients with Alzheimer’s disease.

• Melanotransferrin mRNA widely expressed in tissue and also in salivary glands.

• Levels of melanotransferrin mRNA do not change in presence or absence of an iron chelators or iron source.

• Functional studies shown that melanotransferrin transports iron from iron-citrate complexes but not from iron-transferrin complex.

• Melanotransferrin has minor role in iron uptake from iron citrate complexes.

IRON BIOAVAILABILITY IN VEGETABLES

VEGETABLES IRON IN /mg

Mushroom, pleurote 1.74

Potatoes 0.76

Cabbage, Collards 0.19

Cabbage, Green 0.59

Roasted Pumpkin and Squash Seeds 15

Spinach 2.71

Sesame Butter(Tahim) and Seeds 14.8

Sundried Tomatoes 9.1

Dried Apricot 2.2

Lentils 6.20

IRON BIOAVALABILITY IN FRUITS

FRUITS IRON IN/mg

Apples, without skin 0.07

Blackberries 0.57

Dates 1.15

Pears, without skin 0.25

Pineapple 0.37

Raspberries 0.57

IRON BIOAVALABILITY IN GRAINSGRAINS SERVING IRON IN /mg

Wheat Flour, White Cake, Enriched

1 cup 10.03

Wheat, Soft White 1 cup 9.02

Wheat, Hard White 1 cup 8.76

Sorghum 1 cup 8.45

Corn flour, Masa, Enriched White

1 cup 8.22

Corn flour, Masa, Enriched Yellow

1 cup 8.22

Millet 1 cup 6.02

Oats 1 cup 7.36

Quinoa 1 cup 2.36

Rice Bran, crude 1 cup 21.88

MORE HEME IRON RICH FOODS

Meat IRON IN/mg

Beef Lean Chuck 2.9mg

Turkey Meat(Dark) 2.3mg

Chicken Leg(Roasted) 1.3mg

Tuna(Bluefin) 1.3mg

Halibut 1.3mg

Pork Chops(Loin) 1mg

White Tuna 0.9mg

Shrimp(Prawns/Camarones) 1mg

Liver 30.5mg

Clams, Oysters and Mussels 28mg

RECOMMENDED DIETARY IRON INTAKE

IRON mg per Day

Infants (7-12 months) 11

Children (1-13 years) 8-10

Boys (14-18 years) 11

Girls (14-18 years) 15

Women (19-50 years) 18

Pregnant Women 27

Breastfeeding Women 9-10

Women over 50 years 8

Men over 19 years 8

CONCLUSION

Heme and non-heme iron are absorbed differently.

Meat, fish, poultry and vitamin C improve the absorption of non-heme iron.

Tannin, oxalate, phytates and dietary fibre all reduce the absorption of non-heme iron.