Carbohydrate is the most controversial macronutrient.
Well maybe not, fats are controversial too. But the science on fats is so clear the politics are becoming irrelevant.
The debate around carbohydrate is interesting and usually well informed but its polarized between government and medical dietetics with low fat high carb advice on one side and on the other side a great interest in low carb diets.
Carbohydrate Feeds the Biome
A good way to look at carbs is from the view of the bowel flora, the intestinal biome. What it likes to be fed, what kind of environment and food flow it likes. Carbohydrate is its main food and when its happy we are happy.
The biome is as diverse as a great rainforest; varying across the land, on the shaded sides of mountains and in the deep gulleys. In the intestine there are different species in the central lumen, against the mucous lining, and deep in the crypts in the villi. Differing from the small intestine all the way to the colon. About 2/3 are core species, the remainder are variable and change with diet, travel, moving. There is a small transient population of short lived species.
The biome thrives on a wide variety of soluble and insoluble fibre. Vegetables of all forms are an ideal fibre. We inevitably feel like adding more starch, sweet potato is excellent. Traditional grain especially wheat can be problematic but the newly arrived ancient grains are good.
Other Ways to Benefit the Biome
The wider the variety of dietary fibres the wider the diversity and viability of the biome. Another factor is how widely we experience the outdoors – forest and fields, animals, soil. Hunter gatherers in Tanzania will have a very different biome to a western city dweller; so will a bunch of kids wrestling on the ground like scrub cattle compared to kids mostly living indoors.
So saying, different biome populations in different people is not a problem as long as its diverse, well fed, happy and functioning well – digesting food and making butyrate to feed the villi in the intestinal wall.