cells. For example, vitamin C refreshes the
chemical state of metal components in many
enzymes, and helps with the synthesis of
connective-tissue collagen. Vitamin A, which
our bodies make from a precursor molecule in
plants called beta-carotene (p. 267), helps
regulate the growth of several different kinds
of cells, and helps our eyes detect light. Folic
acid, named from the Latin word for “leaf,”
converts a by-product of our cells’
metabolism, homocysteine, into the amino
acid methionine. This prevents homocysteine
levels from rising, causing damage to blood
vessels, and possibly contributing to heart
disease and stroke.
Genetic Engineering and Food
The most far-reaching development in
20th-century agriculture was the
introduction in the 1980s of genetic
engineering, the technology that makes it
possible to alter our food plants and