Almonds are a popular food consumed on their own or as an ingredient in many sweet and savory foods around the world. L-lysine is an essential amino acid found in many foods, including almonds. In the September 2005 edition of “Plant Foods in Human Nutrition,” a team of researchers led by Florida State University professor Shrihdar K. Sathe, Ph.D., reviewed the l-lysine content and other nutritional characteristics of several varieties of almonds popular in the United States.
Sathe and colleagues report that there are three popular varieties of American almonds, commonly known as Carmel, nonpareil and Mission, based on their shape or area of origin. All three store their protein in the form of amandin, a storage protein unique to almonds that contains relatively little l-lysine. The l-lysine content varies slightly -- less than 3 percent -- between varieties of almonds.
MDConsult.com says that l-lysine plays an important role in growth, wound healing, calcium absorption and the conversion of dietary fats into energy. L-lysine is “essential,” which means that the body must obtain it from foods because it cannot make it on its own. A diet low in l-lysine leads to muscle breakdown in order to free l-lysine for essential activities. Sathe and colleagues say that almonds are a poor source of l-lysine.
The Food and Nutrition Board of the Institute of Medicine says that the estimated average requirement for l-lysine varies by age and body size. Infants need the most, proportionately, about 40 milligrams per pound of body weight. Children between 1 and 3 need about 26 milligrams per pound of body weight per day, and children between 4 and 12 need about 20 milligrams. L-lysine requirements stabilize around the age of 13. Both adults and children 13 and older require about 16 milligrams per pound of body weight. A single serving of almonds contains about 145 milligrams of lysine.
Vegans who rely heavily on almonds for protein might become deficient in l-lysine. Symptoms of l-lysine deficiency, according to the University of Maryland Medical Center, include fatigue, nausea, dizziness, loss of appetite, agitation, bloodshot eyes, poor growth, anemia and reproductive problems. A doctor can diagnose l-lysine deficiency with blood tests or dietary history. Treatment consists of increasing consumption of foods rich in l-lysine, such as soy products and legumes for vegans and poultry, fish and dairy products for all others.
The l-lysine content of almonds has attracted attention because of a purported relationship between nut consumption and herpes outbreaks. While almonds contain little lysine, they are rich in another amino acid, l-arginine, which is thought to trigger activation of the herpes simplex virus. L-lysine also appears to enhance calcium absorption, a potentially important application for people who suffer from osteoporosis. However, compared to cow’s milk and soy milk, almond milk contains very little l-lysine and calcium, making it a poor choice for people attempting to treat osteoporosis through diet.
- “Plant Foods in Human Nutrition”; Almond Protein Quality; Shrihdar K. Sathe, Ph.D. et al.; Sept. 2005
- National Academies Press: Institute of Medicine: Dietary Reference Intakes: Protein and Amino Acids
- University of Maryland Medical Center: Lysine
- MDConsult.: Drug Monographs: Lysine
- “Integrative Medicine”; David Rakel, M.D.; 2007
- “Modern Nutrition in Health and Disease”; Maurice E. Shils, M.D. et al.; 2005