IRON FORTIFICATION 

1. Introduction

• Iron is an essential mineral required for many bodily functions, including the formation of haemoglobin, but can be harmful when taken in excess.
• One of the methods suggested for the treatment of iron deficiency anaemia is the fortification of food with iron.
• Typically, a chosen food staple such as wheat, rice, or even salt, is fortified to provide up to two-thirds (10mg/day) of the iron requirement of adult women and almost the entire daily requirement of men.
• Thus, excess consumption of iron can occur if one habitually consumes a balanced quality diet, to begin with, or exceeds limits for consumption of fortified food.

2. Tolerable upper limit 

• There is a defined level of iron intake beyond which the risk of adverse events begins to increase.
• This is called the tolerable upper limit of intake and is set at 40 mg/day.
• It will especially be deleterious for populations who have iron overload states like patients with thalassemia.
• Once iron is absorbed, it is thought that its excretion is steady and very small, except when bleeding takes place, as with menstrual bleeding.
• Thus, women can excrete iron from the body but men cannot. This makes men vulnerable to excess iron intake.
• Recent studies showed that with fortification, there is increased excretion of iron in children.
• It is not known exactly how or through what route this extra excretion takes place.
• The extra iron is likely lost through the intestine, where cells of the intestinal lining exfoliate or drop off, and thereby deposit their iron into the intestine lumen for excretion or through the urine.
• Nevertheless, beyond the excess stores, the net effect of iron provision through fortification on haemoglobin formation is likely to be lower than thought.
• To the extent that the body can, it will try to regulate iron absorption. But excess iron in the fortified diet can remain unabsorbed.
• Typically, it is expected that just 510 per cent of the ingested iron is absorbed. The rest is excreted.

3. Harmful effects

• Studies have shown that unabsorbed iron can lead to inflammation in the gastrointestinal lining and disrupt the colonic microbiota with long-term consequences.
• The irritation of the lining may present itself clinically as abdominal cramps, constipation or diarrhoea.
• In addition, the irritation of mucosa can also lead to gastrointestinal blood loss.
• An excess of iron in the gastrointestinal tract can impair the absorption of other minerals.
• A more pressing worry is that excess iron has been closely linked to diabetes.
• Iron can cause oxidative stress in the body which can damage cells, proteins and DNA with long-term consequences.
• This chronic oxidative stress leads to the impairment of mitochondrial beta-oxidation of long-chain fatty acids.
• This abnormal fat oxidation leads to excessive serum triglceridemia and excessive accumulation of triglycerides in muscle and liver tissues.
• An analysis of data on blood biomarkers of chronic disease risk from the Comprehensive National Nutritional Survey in Indian adolescent Children showed that for every 10mcg/L increase in serum ferritin (the storage state of iron), the risk of having high fasting serum glucose, total cholesterol, triglycerides and hypertension increased proportionately.
• A scenario analysis of these data showed that if an additional 10 mg of iron/day were provided (by fortification), the prevalence of high fasting serum glucose could increase by 214 per cent across different socioeconomic groups.
• In very high amounts, iron also has a role to play in hepatic stellate cell activation and excessive deposition of extracellular matrix in the liver.
• This can lead to liver fibrosis, with subsequent progression to cirrhosis.

4. Individual approach

• Even though iron fortification has been successful in addressing iron deficiency, it is important to consider the dangers of consuming too much iron.
• Rather than adopting mandatory iron fortification programmes where unsupervised high iron intakes are instituted across a diverse population, it is imperative to develop individualised strategies and ensure thorough monitoring to detect any adverse events at the earliest.
• There is no doubt that some segments of the population need extra dietary iron but not all.
• Eventually, precision in public health is essential if we are to avoid the risk of iron overload and the potential for long-term chronic illnesses.
• As a public health strategy, the pendulum should not swing to the other side.