The human body can synthesize vitamin D when skin is exposed to ultraviolet radiation from the sun.
Once the liver glycogen stores are depleted, the body cannot synthesize glucose, and severe hypoglycemia results.
It is not an essential amino acid, which means that the human body can synthesize it.
Vitamin D, which the body synthesizes from sunlight, helps the body absorb calcium.
But according to the American Medical Association, the body will never synthesize enough vitamin A from food sources to reach toxic levels.
Generally, though, the body can synthesize most of its own fats and doesn't need to consume them.
For those fats that the body can synthesize, it would make them if none were consumed through a person's diet.
The human body synthesizes some of the choline it needs, and people vary in their need for dietary choline.
Rather than deriving these enzymes from food (or pills) the body synthesizes those it needs from the materials in the diet.
"My body synthesizes the enzyme it needs."