The small intestine is the primary organ responsible for absorbing water into the bloodstream.
How Water Absorption Works
The process begins after water passes through the stomach. The small intestine, a remarkably long organ (approximately 20 feet in length), efficiently absorbs water through its walls. This absorbed water then enters the bloodstream. Up to 60% of the adult human body is composed of water, highlighting the vital role of water absorption in maintaining bodily functions. [^1, ^2] Water absorption in the small intestine starts quickly, with absorption occurring as early as 5 minutes after ingestion and peaking around 20 minutes later. ^10 The kidneys also play a crucial role in regulating water balance by releasing or retaining water in urine. ^3 The body maintains its fluid balance by ensuring the amount of water consumed equals the amount lost through various processes such as urination, sweating, and respiration. ^6
- Small Intestine: The primary site of water absorption.
- Kidneys: Regulate water levels in the body through urine production.
- Bloodstream: Water absorbed by the small intestine enters the bloodstream, transporting it throughout the body.
The body needs water for various functions, including:
- Transporting nutrients and oxygen.
- Regulating body temperature.
- Removing waste products.
- Lubricating joints.
The statement "The body takes what it needs from what we eat and drink" clearly shows that water consumption is essential. [^8] Even blood, which is 55% plasma (90% water), requires water for its composition and function. [^5] Dehydration occurs when water loss exceeds intake, impairing bodily functions. ^7
[^1]: The majority of the water you drink is absorbed into your bloodstream. Absorption occurs after water passes through the stomach and into the small intestine. The small intestine, at around 20 feet long, is the organ primarily responsible for water absorption through its walls and into the bloodstream.
[^5]: ... About 55% of blood is comprised of plasma, of which 90% is water. So ...
[^8]: Urine contains waste and extra fluid left over after the body takes what it needs from what we eat and drink. Each day, adults pass about a ...
