Understanding Glycemic Index: What Nigerian Studies Reveal About the Foods on Our Plates

Glycemic index comes up often in conversations about diet and blood sugar, but it is frequently used as a loose stand-in for “healthy” or “unhealthy” rather than the specific, measurable concept it actually is. A closer look at what Nigerian research has found on the subject offers a more precise picture of how the country’s most common foods actually behave in the body.

Glycemic index, or GI, ranks carbohydrate-containing foods by how quickly they raise blood glucose after eating, measured against pure glucose, which is scored 100. Foods scoring 55 or below are classed as low-GI, those between 56 and 69 as medium, and anything from 70 upward as high-GI. A higher GI means a faster, sharper rise in blood sugar, while a lower GI means a slower, more gradual one.

Several Nigerian studies have directly measured the glycemic index of local staples using postprandial blood glucose testing, and the findings are consistent. Most traditional processed swallows, including garri and eba, fufu, amala, pounded yam and tuwo, sit in high-GI territory, generally in the 75 to 97 range. Foods that fall into lower categories include legumes, with beans and similar pulses consistently ranking among the lowest-GI foods commonly eaten in Nigeria due to their combination of low GI, high fibre and protein content, as well as non-starchy vegetables like leafy greens and okro, which have minimal impact on blood glucose on their own. Whole, less-processed grains and oats also tend to digest more slowly than heavily refined flours, since they retain more of their natural fibre structure.

One detail that surprises many people is how inconsistent GI figures can look across different studies for the same food. Unripe plantain, for instance, has been measured as both a relatively low-GI and a high-GI food depending on the study. Researchers say this isn’t a contradiction so much as evidence of how sensitive GI is to preparation method. Pounding raises GI, with pounded yam consistently testing higher than boiled yam in the same studies, because pounding breaks down the food’s structure and speeds up digestion. Frying, in some foods, can lower GI relative to boiling by changing texture and slowing enzyme access to starch. Ripeness matters too, particularly for plantain, since riper, sweeter plantain digests faster than less-ripe plantain, which is part of why plantain-based flours are typically made from the unripe fruit rather than the riper stage most people fry. What a food is eaten alongside also changes its effective impact, since rice eaten with beans and vegetables produces a different glucose response than rice alone, a combined effect sometimes measured separately as glycemic load, which accounts for portion size rather than food type alone.

The practical implication, according to the research, is that GI is not a fixed property of an ingredient. It depends on preparation, on what else is eaten with it, and on how much of it is consumed.

Given that variability, GI functions best as a general compass rather than a precise number to chase for every food. A few conclusions hold up consistently across the studies. Most traditional Nigerian swallows, prepared conventionally, sit in high-GI territory, a finding well established enough to work from rather than assume otherwise. Adding fibre, whether through vegetables, beans or a fibre-enriched swallow flour, measurably slows the glucose response of a meal, regardless of the exact GI figure attached to any single ingredient. And portion size and meal composition usually matter more day to day than obsessing over a specific GI number.

That last point is the reasoning Elkris Foods says sits behind its own approach to formulation. Rather than searching for a naturally low-GI traditional swallow, which the research suggests largely doesn’t exist, the company builds additional soluble fibre directly into its flours to change the food’s digestion mechanics at the source, a more reliable lever, it argues, than hunting for marginal GI differences between similarly refined starches. Its range spans a plain Oat Flour through to the more fibre-concentrated Oat & Fibre Flour, offering different fibre levels for different households while working from the same underlying GI logic rather than any single ingredient positioned as a cure-all.