The phrase "are not absorbed" is correct and usable in written English.
It can be used in contexts discussing processes, reactions, or situations where something is not taken in or incorporated.
Example: "The nutrients in the soil are not absorbed by the plants due to the lack of moisture."
Alternatives: "are not taken in" or "are not incorporated".
Unfortunately, many iron supplements are not absorbed well, either.
The lining of the small intestine is damaged so nutrients are not absorbed properly.
Therefore, they are not absorbed from the intestine, and they do not enter the brain.
Fecal softeners are not absorbed from the gastrointestinal tract and act to increase the bulk of the feces.
Some, which are not absorbed, can be administered orally to treat specific localized infections in the gastrointestinal tract.
But the colors that are not absorbed are still reflected, and thus visible, resulting in gold aluminum or dark blue tungsten.
Astronomy from Earth's surface is limited to observation in those parts of the electromagnetic spectrum (see electromagnetic radiation) that are not absorbed by the atmosphere.
Protectants are not absorbed by or translocated through the plant; thus they protect only those parts of the plant treated before invasion by the pathogen.
Solids are not absorbed through the skin because the skin is generally not covered with liquid and because pinocytosis does not operate in dead cells.
Not only have simple blood tests apparently demolished what regulators have long argued – that Bt toxins are not absorbed – but the paper also illustrates how easy it would have been for regulators to check their test-tube assumptions.
(Pigments absorb light of a particular wavelength; those wavelengths that are not absorbed are reflected and may be perceived as colour hence, for example, the green colour of many plants.) The inner membrane of the chloroplast is folded into flat tubes, the edges of which are joined to hollow sacklike disks called thylakoids.
