lead : 1. (noun) A nutrient that is essential to plants and animals but toxic to humans. 2. (verb) To show the way.

leptin: Leptin is secreted by fat cells throughout the body. Not only do they “talk” to the brain, but they may also communicate directly with each other and cut out the middleman, the hypothalamus.

leucine: An essential branched-chain amino acid. Leucine is essential for growth as a stimulator for protein synthesis in muscle.

lipids : Chemical family name for fats and related compounds such as cholesterol is lipids (from lipos, the Greek word for fat).

lipoproteins : Also known as LDLs or “bad cholesterol,” lipoprotein ferry cholesterol around and out of the body.

lithium : A metal found in the soil and used medically in the treatment of manic depressive disorders.

lycopene : The red carotenoid in tomatoes.

lysine : An essential amino acid best known for lessening and preventing herpes simplex virus infections.