Blood plasma transports nutrients because they dissolve or attach to things in its watery mixture and then flow through blood vessels to every cell in the body.

How plasma carries nutrients

  • Plasma is mostly water (about 90–92%), which makes it a fluid medium that can flow easily through blood vessels.
  • After food is digested in the small intestine, nutrients such as glucose, amino acids, vitamins and mineral ions dissolve in this water-based plasma and enter tiny blood capillaries.
  • These dissolved nutrients are then carried by the moving blood plasma all around the body and delivered to body cells, especially where capillaries are narrow and blood flows slowly, giving cells time to absorb them.

Some nutrients, especially fats, do not dissolve well in water, so plasma uses special carrier proteins:

  • Fatty substances are packaged into lipoproteins or carried attached to plasma proteins like albumin, which makes them soluble in the watery plasma and allows them to be transported safely.

So, because plasma is a water-based solution containing dissolved nutrients and carrier proteins, it can transport the products of digested food to every cell that needs them for energy, growth and repair.