How is Nutrition Distributed in the Body? A Comprehensive Guide

January 5, 2026 •

3 min read

The average human body contains approximately 5 liters of blood, which acts as the body's primary transport vehicle for delivering nutrients. Understanding exactly how is nutrition distributed in the body reveals a complex and highly coordinated physiological process essential for survival.

Quick Summary

The journey of nutrients begins with digestion and leads to two distinct transport systems, the bloodstream and the lymphatic system. Nutrients travel via these pathways to the body's tissues, where they are absorbed by individual cells using both passive and active transport mechanisms.

Key Points

Digestion is the essential first step: Food is broken down by the digestive system into absorbable molecules like glucose, amino acids, and fatty acids before distribution.
Two main transport systems are used: The circulatory system handles water-soluble nutrients, while the lymphatic system transports fats and fat-soluble vitamins.
The liver acts as a central processor: Water-soluble nutrients travel directly to the liver via the hepatic portal vein for processing, storage, and detoxification before wider distribution.
Fats bypass the liver initially: Fat-soluble nutrients are absorbed into the lacteals of the lymphatic system, eventually joining the bloodstream near the heart.
Capillaries are the exchange sites: The vast capillary network is where nutrients and oxygen are transferred from the blood into the fluid surrounding body tissues.
Cells use active and passive transport: Individual cells absorb nutrients from the interstitial fluid across their membranes using energy-dependent active transport or energy-free passive transport.

The First Step: Digestion and Absorption

Before nutrients can be distributed throughout the body, the food we eat must be broken down into absorbable components. This multi-stage process begins in the mouth, continues in the stomach, and culminates in the small intestine. Enzymes, acids, and muscular contractions work together to convert complex carbohydrates into simple sugars (glucose), proteins into amino acids, and fats into fatty acids and glycerol.

The Small Intestine: The Nutrient Gateway

The small intestine is the primary site for nutrient absorption, made highly efficient by its unique structure. Its inner walls are lined with millions of tiny, finger-like projections called villi, which are themselves covered in microvilli, further increasing the surface area for absorption exponentially. It is here that the digested nutrients are transferred from the digestive tract into the body's two major transport systems.

Dual Transport Pathways: The Circulatory and Lymphatic Systems

Nutrients are categorized into two groups based on their solubility, and each group takes a different pathway for distribution.


Aspect	Circulatory System (Blood)	Lymphatic System (Lymph)
Primary Function	Transports most water-soluble nutrients and oxygen to cells.	Absorbs and transports fats and fat-soluble vitamins.
Absorbs	Water-soluble vitamins (B and C), minerals, glucose, and amino acids.	Fat-soluble vitamins (A, D, E, K), fatty acids, and glycerol.
Carries	Blood plasma acts as the solvent, carrying nutrients dissolved within it.	Lymph, a watery fluid, carries fats packaged into chylomicrons.
Primary Route	Absorbed into capillaries, travels via the hepatic portal vein to the liver, and then to the heart.	Absorbed into specialized lymph vessels (lacteals) and bypasses the liver initially.

Water-Soluble Nutrient Distribution via Blood

Once absorbed into the capillaries of the small intestine, water-soluble nutrients are collected by the hepatic portal vein, which carries nutrient-rich blood to the liver. The liver processes, stores, converts, and detoxifies these nutrients before they enter general circulation. From the liver, nutrients are released into the bloodstream and distributed to all body cells.

Fat-Soluble Nutrient Distribution via Lymph

Fats and fat-soluble vitamins are absorbed into lymphatic vessels called lacteals within the intestinal villi. Within intestinal cells, fatty acids are repackaged into chylomicrons and released into the lacteals. This nutrient-rich lymph travels through the lymphatic system, eventually joining the bloodstream near the heart via the thoracic duct, bypassing the liver initially.

Cellular Exchange: The Final Delivery

The final stage of distribution involves delivering nutrients from the transport systems to individual cells. The circulatory system's network of arteries branches into capillaries, where blood flow slows. This allows oxygen and nutrients to diffuse from the capillaries into the interstitial fluid surrounding the cells. Cells then take up these nutrients from the interstitial fluid through their cell membranes.

Mechanisms of Cellular Uptake

Cells use several methods to move nutrients across their membranes:

Passive Transport: This energy-free process moves molecules from higher to lower concentration, including simple and facilitated diffusion.
Active Transport: This energy-dependent process moves molecules against their concentration gradient.
Endocytosis: Large molecules or particles are engulfed by the cell membrane and brought inside in a vesicle.

Conclusion: A Symphony of Systems

The distribution of nutrition in the body is a complex, cooperative process. Digestion breaks down food, and the small intestine absorbs nutrients. Water-soluble nutrients travel via blood to the liver for processing, while fats travel via lymph, eventually joining the bloodstream. Nutrients are delivered to cells through capillaries, and cells use various mechanisms for uptake. This intricate system ensures that every cell receives the necessary resources for function.

For a visual overview of nutrient transport, check out a video explanation on Pearson's website.

Frequently Asked Questions

After absorption in the small intestine, water-soluble nutrients enter the bloodstream, while fat-soluble nutrients are absorbed into the lymphatic system.

Water-soluble nutrients are carried by the bloodstream. They first travel through the hepatic portal vein to the liver for processing before being released into general circulation.

Fats and fat-soluble vitamins are not water-soluble, so they are absorbed into specialized lymphatic vessels called lacteals, which carry them through the lymphatic system before they enter the bloodstream near the heart.

The liver processes, stores, and modifies absorbed water-soluble nutrients. It also regulates blood glucose levels and detoxifies substances before they are distributed to the rest of the body.

Nutrients diffuse out of the capillaries, where blood flow is slow, and into the interstitial fluid surrounding the cells. The cells then take up these nutrients from the fluid.

Passive transport moves nutrients across cell membranes without using energy, following a concentration gradient. Active transport requires energy (ATP) to move nutrients against a concentration gradient.

Capillaries are the smallest blood vessels, and their thin walls allow for the exchange of nutrients, oxygen, and waste products between the blood and the surrounding tissues.