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Nutrition 101 - Glossary - L

L-theanineDefinition - L-theanine is an amino acid, or protein building block, that is water soluble; it is found in tea and some mushrooms. Relevance - L-theanine has been associated with being protective against stroke and cancer, and a potential source of stress relief with relaxant and antioxidant effects.

LactoseDefinition - Lactose is a sugar found naturally in milk and milk products. Relevance - Lactose intolerance is highly prevalent and characterized by an inability to digest lactose due to an absence of the enzyme lactase; symptoms of abdominal pain, gas, bloating, and nausea can be managed with dietary changes.

LDLDefinition - Low-density lipoproteins (LDL) are small packages made of fat on the outside and protein on the inside that carry cholesterol throughout the body. Relevance - High LDL ("bad") blood cholesterol can lead to a buildup of cholesterol in the arteries, forming plaques and increasing the risk of heart disease.

Lectins– Definition – Components of plants (legumes, grains, nuts and seeds) used to defend against animals trying to eat the plant. Lectins can cause digestive upset when eaten raw. Relevance – Lectins are significantly reduced when the foods that contain them are prepared with heat (particularly moist heat) and therefore can be safely eaten by people when adequately cooked.


LensDefinition – A transparent, flexible tissue of the eye, located directly behind the iris and pupil. It helps focus light and images on your retina. Relevance – In cataracts, proteins in the lens of the eye become damaged, resulting in blurry, hazy vision. If untreated (by surgery), blindness can result.

LeptinDefinition – A hormone produced by fat cells that helps regulate appetite and calorie burn (metabolism). Relevance – If you become overweight or obese, your brain can become resistant to leptin’s appetite-suppressing effects. That resistance can result in more hunger and slower metabolism.

Linoleic acidDefinition - Linoleic is an essential polyunsaturated fatty acid, the most abundant in the diet.   Relevance - Linoleic acid is important to cell membranes in the body and can be used in cell signaling and as an energy source; linoleic acid is found in plant oils, nuts, seeds, meat and eggs.

LuteinDefinition - Lutein is a nutrient found in green leafy vegetables and eggs, often with zeaxanthin, both of which have been shown to benefit eye health. Relevance - Lutein and zeaxanthin are the only two naturally-occurring carotenoids that are highly concentrated in the eyes. In the retina, they can reduce the risk of cataracts and age-related macular degenerative by filtering harmful blue light and acting as antioxidants.

LycopeneDefinition - Lycopene is a carotenoid pigment that gives some red fruits and vegetables their color and exists in high amounts in tomatoes and tomato products. Relevance - Studies have shown that lycopene may help in preventing prostate, breast, lung, colon, bladder, pancreatic and ovarian cancer, as well as heart disease and atherosclerosis.