Lysine is an essential amino acid that the body cannot make, so it must be obtained from food or supplements. Within the body, lysine is used as a building block for a variety of protein-based structures and there is some scientific evidence that high levels of it deter the proliferation of the herpes simplex virus. Cucumber is a moderate source of lysine and other amino acids.
Cucumbers, also known as Cucumis sativus, are closely related to melons, zucchini and other squashes. Large varieties with thick skins are typically sold as fresh produce, whereas small thin-skinned types are usually marinated in vinegar and sold as pickles. Cucumber contains most of the amino acids needed by the body, but in small amounts, especially compared to much richer sources such as meat or legumes. The most prevalent amino acid in cucumber is glutamate, followed by arginine, aspartate and lysine. Specific amounts vary according to variety, soil quality, growing conditions and measuring techniques, but 1 cup of raw cucumber with the skin on usually contains between 30 and 40 milligrams of lysine.
Functions of Lysine
Lysine is involved with calcium absorption and needed to make enzymes, hormones, antibodies and collagen, which is the elastic-like compound within skin and other connective tissues. It also plays a role in the production of carnitine -- a compound responsible for converting fats into energy and lowering circulating levels of cholesterol. Lysine deficiency is uncommon, but when it occurs it can lead to fatigue, dizziness, reduced appetite, agitation, anemia, weakened immunity and reproductive disorders. Lysine supplementation is often associated with combating herpes and some studies have found that taking it on a regular basis -- at doses of at least 1,000 milligrams daily -- may help prevent outbreaks of cold sores and genital herpes, according to the University of Maryland Medical Center. Lysine has antiviral properties because it blocks the activity of arginine, an amino acid that promotes the replication of the herpes simplex virus.
Lysine vs. Arginine
Foods high in arginine and lower in lysine -- such as nuts, seeds, chocolate and whole-wheat products -- tend to promote herpes outbreaks. Conversely, foods high in lysine and low in arginine may offer some protective benefits. Cucumber contains similar amounts of lysine and arginine, but in relatively low amounts, so it's unlikely that cucumber either deters or promotes herpes breakouts to any significant extent. However, more research is needed before specific health claims can be made.
Beef, poultry, fish, dairy and eggs are all excellent sources of lysine. For vegetarians and those on restricted diets due to allergies, very good vegetable sources of lysine include soy beans, kidney beans, quinoa, peas, spinach, carrots, beetroots, turnips, alfalfa, plums and papaya.