A study across eight States in India involving 4,613 participants that included adolescents (647 girls and 674 boys), adults (931 women and 927 men) and elderly (714 women and 720 men) has found that the prevalence of anaemia has been overestimated by previous surveys. While the NFHS surveys measured haemoglobin using finger prick-based capillary blood, the latest multi-institutional study carried out by a team led by Dr. Anura Kurpad from St. John’s Medical College, Bengaluru, used venous blood to measure haemoglobin and iron status through ferritin. The other institutions involved in the study include ICMR-NIN, Hyderabad, Sitaram Bhartia Institute of Science and Research, New Delhi, CSIR-IGIB, New Delhi, CSIR-CCMB, Hyderabad, Banaras Hindu University, and KEM Hospital, Pune. The results have been posted as a preprint; preprints are not peer-reviewed.

Capillary blood haemoglobin will be an underestimate of the true value as the red blood cell count in the capillary blood will be a little lower than venous blood due to a phenomenon called plasma-skimming. Also, tissue fluid gets mixed with capillary blood while drawing the blood sample leading to dilution and thus a reduction in haemoglobin value. The WHO has also recently recommended that anaemia be diagnosed from venous blood estimations of haemoglobin.

The study found that anaemia prevalence was predominantly of the mild variety. Overall, 18.4% of the entire sample were mildly anaemic, 14.7% were moderately and 1.8% were severely anaemic. As expected, the overall prevalence of anaemia was higher in women compared with men. The prevalence of moderate anaemia was significantly higher in women (22%) compared with men (7.6%). Anaemia prevalence was 44%, 41% and 45% in adolescent girls, adults and elderly women, respectively. In the case of adolescent boys, adults, and elderly men, anaemia prevalence was 24%, 21% and 37%, respectively.

In comparison, the prevalence of anaemia was much higher as per the NFHS surveys that used capillary blood— 60.8% for women, 62.6% for adolescent girls, 26% for men and 31.8% for adolescent boys.

As per the present study, the prevalence of total anaemia was very high in the state of Assam (69.8% overall; 78.3% for women) followed by Odisha (55% overall; 63% for women). At 12.1% overall and 14.6% for women, Meghalaya had the least anaemia prevalence, followed by Telangana (16.9% overall; 24.6% for women), West Bengal (19.5% overall; 28% for women), Tamil Nadu (23.7% overall; 32.4% for women), Gujarat (33.9% overall; 44.2% for women), and Madhya Pradesh (45.4% overall; 55.9% for women).

Interestingly, the prevalence of iron deficiency for the whole group was just 18.4%. It was highest among adolescent girls (31.5%) followed by adult women (27.7%), and elderly women (13.6%). The prevalence of iron deficiency was 16.0%, 10.7% and 11.2% for adolescent boys, adults, and elderly men, respectively. Even among anaemic women (42.6% with all grades of anaemia), only about a third was due to iron deficiency. Among elderly women (40.9% with all grades of anaemia), only about a fifth had iron deficiency. Only in the case of adolescent girls did anaemia due to iron deficiency become relatively high at 45%. The major proportion of anaemia in all groups was associated with ‘unknown causes’.

Even in the case of Assam where the prevalence of anaemia was highest (69.8% overall; 78.3% for women), iron deficiency was only 12.3% overall and 18.9% in women. In the case of Tamil Nadu where the prevalence of anaemia was 23.7% overall and 32.4% for women, iron deficiency was rather high at 22.8% overall and 38.2% in women. Interestingly, while Assam had the highest prevalence of anaemia (69.8% overall) and Meghalaya had the least anaemia prevalence at 12.1% overall, iron deficiency as a driver of anaemia was comparable and low in both States — Assam (12.3% overall) and Meghalaya (12.6% overall). “Only one-fourth of 42% of women with anaemia were due to iron deficiency. Yet, everybody assumes that iron deficiency is the main cause of anaemia in India,” says Dr. Kurpad. “Though anaemia is caused by multiple factors including vitamin B12 and folate deficiency, and inflammation, the focus has primarily been only on iron deficiency.”

With iron deficiency playing a relatively low role in anaemia, Dr. Kurpad stresses that policies to provide iron supplementation for the entire population of India have to be reconsidered, particularly due to the dangers of excess iron intake. “It is not easy to excrete iron, and too much iron can cause oxidative stress on all organs,” he cautions. “There should be a change in focus from supplementing iron to a broader focus on all nutrients and the environment.” For instance, inflammation due to poor sanitation or air pollution can suppress the production of red blood cells in the bone marrow as well as reduce iron absorption, Dr. Kurpad says. “The focus should also be on reducing inflammation, which is best achieved naturally through increased consumption of fruits and diversity in diet to improve the intake of all nutrients,” he says.

Currently the diet of a large percentage of the Indian population is mainly cereal-based with very little to zero coloured vegetables and fruits. “Due to climate change, the protein, vitamin and mineral content in cereals is dropping,” he says. “It’s time we diversify from cereals to millets which are more resilient. Though phytates in millets can reduce absorption, millets contain higher amounts of iron and calcium leading to increased net intake.”

As per the study, mild anaemia prevalence was higher among those eating a vegetarian diet compared with those eating a non-vegetarian diet. However, the prevalence of moderate and severe anaemia was almost similar in both diet groups. “This speaks against a sole nutrient aetiology for moderate and severe anaemia,” the paper notes.

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