Lentils -- a grain legume botanically known as Lens culinaris -- are believed to be among the first crops grown by humans. Historians say they were cultivated as early as 6,500 B.C. A mainstay of Eastern European and Indian cuisine, lentils feature an earthy, nutty taste, and are commonly used in casseroles and soups. Due to their hard seed coatings, lentils can be stored indefinitely, but must be cooked before eating. Lentils are a rich source of protein, carbohydrates, minerals, vitamins and fiber. Lysine, an essential amino acid, is also present in lentils.
The amino acid lysine -- also known as L-lysine -- functions as a building block of protein and is vital for proper growth. In addition, lysine helps produce carnitine, which converts fatty acids into energy and reduces cholesterol. Lysine is also important for the absorption of calcium, and might help prevent bone loss. An essential amino acid, lysine must be obtained through the diet. Good sources of lysine include protein-rich foods such as red meat, poultry, fish, dairy products and legumes. Lentils are one of the best vegan sources of lysine. The University of Maryland Medical Center reports that adults and teens over 13 years old need 5.5 mg of lysine per pound of body weight per day. Supplementary lysine is sometimes used to treat herpes and osteoporosis; it is currently being studied for potential use in treating schizophrenia. Consult your doctor before taking supplementary lysine.
A cup of cooked lentils contains 17.86 g of protein, 0.75 g of fat, 38.69 g of carbohydrates, 15.6 g of fiber and 3.56 g of natural sugars. Lentils are low in fat; low in sugar; high in fiber, protein and carbohydrates; and cholesterol-free. Their caloric investment of 226 calories per cup is more than justified by their dense concentration of nutrients and their high levels of soluble dietary fiber, which help reduce blood cholesterol levels and maintain stable blood sugar. Lentils are high in potassium, containing 731 mg per cup -- more than the amount found in a large banana. The same cup of lentils also offers healthy amounts of iron, phosphorus, selenium, magnesium, niacin and folate.
A cup of cooked lentils contains 1,247 mg of lysine, well over 100 percent of the recommended dietary amount for a 150 lb. individual. The amino acid arginine, which works with lysine to stimulate bone-building cells, is present, at 1,380 mg. Lentils are not too far behind red meat and poultry in lysine content; a 3-oz. ground beef patty contains 1,879 mg of lysine, while a 3 oz. serving of roasted chicken, white meat, contains 1,729 mg. A cup of boiled soybeans, with 1,906 mg, is also a good source of lysine, as is a cup of lima beans, with 983 mg.
In a study published online in 2011 in "Biomed Central Medicine," researchers investigated the ability of lysine to inhibit nitric oxide production and ameliorate schizophrenic symptoms. After administering 6000 mg of lysine a day to 10 schizophrenic patients as an adjunct to conventional antipsychotic medications, the team noted that patients showed a significant decrease in symptoms, with several reporting decreased symptom severity and enhanced cognitive function; one reported a reduction in auditory hallucinations. Levels of nitric oxide in the patients' blood decreased as well. The team called for further study to evaluate lysine's potentially beneficial effects on schizophrenic symptoms.