Why is anemia a common problem among Indian women?

Short answer, anemia in Indian girls is predicated by both biology and socio-economic factors, i.e., unique confluence of biology, culture (diet, marriage age), and great variations in relative affluence and education.

Early marriage ---> early initiation of sexual activity ---> repeated early child bearing ---> recurrent iron loss. This emerges as a major reason for anemia among Indian girls.

Thus, large part of anemia in Indian girls ensues from exacerbation of their inherently greater risk of iron loss attendant to their biology, i.e., pregnancy, child birth and breast feeding. Such exacerbation is cultural, i.e., tendency for early marriages and child births, as well as dietary, i.e., inadequate iron intake and inefficient absorption.

There are also substantial, surprising and inexplicable regional differences.

While there are several types of anemia, I'll restrict my answer to nutritional anemia, specifically to Iron-Deficiency Anemia (IDA), the most common form of anemia in India (1, 2).

Anemia is assessed by measuring circulating blood hemoglobin levels. Typically, there are 3 levels, Mild (10 to 11.9g/dl), Moderate (7 to 9.9g/dl) and Severe (<7g/dl). Typically, in India, severe anemia prevalence tends to be <3%, moderate ranges from 5 to 20%, and mild from 25 to 44%. So the silver lining is that severe anemia levels are low.

Biological factors that contribute to anemia in Indian girls

• The most important biological reason for IDA is inadequate dietary intake of bioavailable iron (3; see figure below).
• There are unique factors associated with Indian diets that may predispose to IDA.

• Being heavily plant-based, it relies on the less bioavailable non-haem form of iron.
• Higher levels of Polyphenol and phytates (Phytic acid).
• Lower ascorbic acid (Vitamin C) to iron ratio which impedes iron absorption.
• Possible average gastric acidity levels that are sub-optimal for iron absorption.

Inadequate dietary iron intake

• Dietary iron is available in two forms, haem or non-haem.
• Haem form of dietary iron is commonly available in meat with the non-haem form in plant foods.
• Haem iron is much better absorbed so already we arrive at a partial answer to the question.
  
  • 90 to 95% of total daily dietary iron in Indian diets is non-haem iron (4).
  • Vegetarian diet iron bioavailability is 10% compared to 18% in omnivorous diets.
  • This means Indian diets are richer in the less efficiently absorbed non-haem iron.
• To compensate for this lower efficiency, nutritionists recommend increasing dietary iron intake by 80% (5).
• Adding another wrinkle, adequate dietary iron levels does not in and of itself explain India's anemia prevalence since Gujarat with ~23mg/day iron intake still has 55% anemia prevalence compared to Kerala's much lower 33% with just 11mg/day iron intake (4).
• Thus, inadequate iron intake explains Indian girls' anemia partly, not wholly.

Defective iron absorption

• More acidic the stomach, better the iron absorption.
  
  • With the caveat that the same studies didn't compare gastric acidity in India to other countries, an old study found that Indian gastric acidity averages ~3.4, much higher than the average of ~2.5 in other countries (6).
• Vitamin C (ascorbic acid) is a strong iron absorption enhancer of plant non-haem iron (7). Indian Vitamin C intake tends to be sub-par.
  
  • In a small (n = 54) 1985 study, vegetarian Indian children with IDA and low vitamin C intake given 100mg Vitamin C during lunch and dinner for 60 days had dramatic improvement, even full recovery from anemia (8).
  • Indian diets tend to have rather low levels of Vitamin C (4, 9).
  • A 2007 study of 214 men and 108 women found sub-optimal Vitamin C intake (recommended 0.4mg/dl) among both (7).
  • Young, married girls in urban Indian slums? Again,  sub-optimal Vitamin C intake (10).

• Indian diets have several dietary components that bind to bioavailable iron preventing its absorption. These include 

• Polyphenols. Tea, herb teas, cocoa, coffee, cinnamon, red wine are polyphenol-rich (11).
• Calcium (12), phosphorus, manganese, zinc.
  
  • Higher intake of Calcium and Phosphorus correlated with anemia in pregnant women (13).
  • Indians' tendency to drink tea/coffee with meals reduces bioavailability of dietary iron (5).

• These are all general reasons for IDA in India. Now let's examine the specific reasons for IDA in Indian girls.
• Here the most pertinent factors are blood loss during menstruation and pregnancies, and loss through breast feeding.
• Blood loss is perhaps the most important one since iron isn't excreted out through urine or feces but only through loss of cells, skin or blood cells for example. 
• Age of highest prevalence of IDA in Indian girls, i.e., 12 to 13 years old, coincides with menarche (first menstruation). Two inter-related problems reveal themselves here.
  
  • One, substantial numbers of Indian girls have menstrual abnormalities but don't seek medical help (14).
  • Two, menstrual blood loss increases daily total iron requirement, consumption of which is sub-optimal for many Indian girls anyway for reasons we've already covered, namely inadequate daily intake and inefficient absorption due to peculiarities associated with Indian diets. Thus, menstruation in Indian girls exacerbates their pre-existing tendency for anemia. 

Socio-economic factors that contribute to anemia in Indian girls

• The National Family Health Surveys (NFHS) are periodic Indian Government health surveys conducted since 1992-1993.
• It shows that currently ~27% of Indian girls aged 15 to 19 years are married. This tracks closely with UNICEF data (15). It's also currently one of the highest rates of early marriage in the world.
  
  • Studies show that married adolescent Indian girls tend to consume diets high in phytates, low in Vitamin C and iron, and unsurpisingly, have high prevalence of IDA (10, 16).
  • In a 2008 study on 118 young, pregnant, poorly educated, low-income Indian girls from North Indian villages, folic acid intakes also tended to be very low (9).
  • On average, Indian women have 297mg of iron loss (blood loss during delivery, iron transfer to newborn, iron content of umbilical cord) versus 150mg of iron conservation (no menstruation) during pregnancy (17). In other words, pregnancy leads to net iron loss. This can only be offset by higher iron intake and absorption.
  • Lactating women obviously have higher daily iron intake requirements, not just to meet infant iron requirement through breast milk but also to make up for loss during pregnancy and delivery.
  • Since daily iron intake requirements are already sub-par in India, deficiency is only exacerbated for pregnant and lactating women.

• Thus, early marriage ---> early initiation of sexual activity ---> repeated early child bearing ---> recurrent iron loss. This emerges as a major reason for anemia among Indian girls.
• In other words, large part of anemia in Indian girls ensues from exacerbation of their inherently greater risk of iron loss attendant to their biology, i.e., pregnancy, child birth and breast feeding. Such exacerbation is cultural, i.e., tendency for early marriages and child births, as well as dietary, i.e., inadequate iron intake and inefficient absorption.

• Several groups have analyzed the Indian Government's NFHS anemia data.
• Careful data mining of the NFHS and other epidemiological data shows that anemia tends to be higher among women who are illiterate, reside in rural areas, work in agriculture, are Hindu, Scheduled Caste (SC) or Scheduled Tribe (ST) (18, 19, 20).
• Poorest urban women are also more likely to be anemic compared to everyone else including their rural counterparts (21, 22). Why? Key factors include
  
  • Lower income, lower access to income and resources.
  • Higher rates of infection due to poor sanitation.
• Factors found to be protective against anemia
  
  • Belonging to middle/upper class.
  • Educated up to high school or higher.
  • Consuming alcohol or pulses.
  • Higher BMI (Body Mass Index).
  • Being Muslim.
• Alcohol consumption protects against anemia, especially among poorer rural women, particularly ST women (21).
  
  • Surprising? Yes and the underlying biology is still a mystery.
  • A robust literature links alcohol consumption to higher iron levels and absorption (23, 24, 25).
  • Alcohol may increase the fermentation process/gastric acid secretion or promote iron solubility/absorption/ferric ion reduction or could itself be an iron source.
• Pulses have high iron content and are also a surrogate for higher income.
• Muslim versus Hindu could be attributed to differences between iron-replete, i.e., non-vegetarian, versus iron-deficient, i.e., vegetarian, diets.
• On the whole, protective factors clearly suggest that higher income ---> better education ---> better diets ---> lower anemia.
  
  • In fact, wealth tracks better with iron sufficiency than even education or caste (26).
  • Education comes second (27).
• One of the most interesting trends is a regional bias in anemia.
  
  • Anemia prevalence is highest among women in the Eastern states of India (4, 19, 22).
  • Assam, Bihar, Jharkhand, Odisha, West Bengal tend to have the highest women anemia prevalence rates (see figures below from 4 and 19). Why? No clear answer.
  • Anemia in general and IDA in particular is multi-factorial. 
  • Likely answer is some combination of biology and culture, i.e., dietary iron and micronutrient deficiencies, and cultural practices such as early marriages, tendency of less educated women, lower incomes.

• While there's substantial literature on high anemia prevalence in Indian women, there are fewer such studies in men.
  
  • In one study on 544 older rural Indian men aged 60 to 84, majority were anemic (28).
  • In fact, Indian men weren't even included in the 1st two NFHS, only being included in the 3rd one (2005-2006) (29).

Anemia rates in Indian women are the highest in the world (3). What could be done to reverse this trend?

• Centralized approaches would be to co-ordinate and encourage manufacture of fortified foods.
• This is something that the FAO (Food and Agriculture Organization) also recommends (30).
• The Micronutrient Initiative began in 2004.
  
  • Through it, the Tamil Nadu Salt Corporation (TNSC) manufactures double- and triple-fortified salts, Vita-Shakti, fortified with iron and folic acid, and Anuka, fortified with iron, Vitamins A and C (31, 32).
• As we explored earlier, certain peculiarities of Indian diets easily lead to IDA.
  
  • Cultural norms are extremely difficult to overcome.
  • Dietary habits are part of such norms.
  • However, there is a silver lining to this conundrum in that several foods that are already part of Indian diets, namely, egg, green vegetables, jaggery, whole wheat, onion stalks, pulses, are iron-rich.
  • Food-based approach is also safer than oral iron supplements which have side-effects such as gastro-intestinal upset (31).
• Better education of Indian girls will go a long way in alleviating their prevailing anemia levels. 
  
  • Would better ensure their conscious and conscientious consumption of iron-rich foods that are already part of Indian diets. So no need to re-invent the wheel in terms of dietary habits.
  • Would encourage their becoming better aware of their basic health parameters such as height, weight, blood type and hemoglobin levels.
  • Would help delay their marriage age.
  • Would help them make better, more empowered decisions regarding childbirth age, spacing between children, and increasing iron, Vitamins A, B12, C, folic acid and riboflavin intake during pregnancy.

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