There is a ton of debate on this and in some cases if you standardize for affluence / income level the differences disappear.

There's a lot of questions about cutoffs used for certain conditions and whether they can be used universally.

BMI is the most obvious example of a measure that should have for different cutoffs for different populations.

The WHO cutoffs for anemia were established over 50 years ago based on predominantly European and North American populations.

Sachdev et al., 2021 identified a subset of "healthy" Indian children from the CNNS data who had no iron, B12, or folate deficiencies and no inflammation.

In this perfectly "healthy" group, the 5th percentile of hemoglobin—the statistical cutoff for anemia—was 1.0 to 2.1 g/dL lower than the WHO standards across all age groups.

The researchers argued that if the population is "healthy" at lower Hb levels, using the higher WHO cutoff misclassifies millions of healthy people as anemic, creating a "false epidemic."

Research published in the European Journal of Clinical Nutrition (2023) examined at what point adding more iron stops increasing a person's hemoglobin.

For Indian women, the "steady state" was reached at a hemoglobin level of roughly 10.8 g/dL.

The WHO cutoff for non-pregnant women is 12.0 g/dL. This suggests that even when an Indian woman has optimal iron stores, her body may naturally maintain a hemoglobin level lower than the Western-derived standard

Most large-scale surveys in India use a finger-prick (capillary) test. Studies have shown that capillary blood often yields lower hemoglobin readings than venous blood (drawn from a vein) because of "interstitial fluid" dilution during the prick.

When the CNNS used venous blood, the anemia prevalence among adolescents was found to be significantly lower than what previous capillary-based surveys had suggested.

Just providing some context. There are many that advocate for universal cutoffs for a variety of reasons. But it should be understood that the interpretation of the data may not represent a meaningfully "deficient" state here. There are several examples of how using "normal ranges" that were based on a subset of the global population may lead us to dubious conclusions.