We know now that the body can produce such substances, but it was a long jump from theory to proof.

So far, genetic engineering has mainly been used to produce substances that already exist in nature.

Cholesterol is an essential substance produced by the body.

Many nuclear power plants produce such substances; usually they are processed to radioactive waste.

Honey is a substance produced by bees from the nectar of plants.

Animals are being genetically transformed so that they can produce drugs and other useful substances in their milk.

People infected with the virus usually have antibodies, substances produced by the immune system, in their blood.

The trick in knowing one's relative is by the amount of substance produced upon antennation.

Nature's functions and diversity are not systematically subject to increasing concentrations of substances produced by society.

Steroids are similar to natural substances produced by the body (hormones) that help reduce inflammation.