Post ingestive systemic nutrient sensing for whole-body homeostasis

Systemic nutrient sensing is a fundamental process that aligns nutrient availability with an organism's metabolic demands. This mini-review explores nutrient sensors in the intestine, pancreas, portal vein, and the brain—organs that detect and convey nutrient status to other tissues via neuronal and hormonal signaling. Unlike oral taste receptors that sense external nutrient inputs, these nutrient sensors monitor post ingestive levels of macronutrients (carbohydrates, proteins, and lipids) and micronutrients (vitamins and essential trace elements such as calcium, magnesium, and zinc) within the body. We describe the specific mechanisms by which each organ discerns fluctuations in nutrient concentration and discuss how these signals integrate into endocrine and neural circuits to maintain whole-body nutrient balance. Finally, by comparing mammalian and invertebrate models such as Drosophila, we offer a comprehensive perspective on how organ-level nutrient sensing upholds metabolic homeostasis across diverse species.