Lemon extract comes in handy to add a little zip to a bundt cake, but it hardly seems like an ingredient that would have health benefits. Yet some alternative practitioners claim near miraculous healing powers for the lowly lemon. Whether or not the claims will hold up to rigorous testing is another matter, although a few laboratory clinical trials have shown some benefit in treating certain medical conditions.
Lemon extract is a concentrated form of oil made from the lemon peel and alcohol. Oils often contain the active ingredients in herbs and plants. The active ingredients that might have health benefits in lemon extract include limonene and citral, found in the outer layer of the peel, sometimes called the zest.
Killing Cancer Cells
Lemon has acquired a reputation in alternative medicine as a cancer killing agent, as evidenced by frequently circulated emails describing the powers of lemon. The Snopes website calls the claim that lemons kill cancer a mixture of true and false information. Some studies using compounds in lemon to kill cancer cells have shown promise against cells in laboratory -- not human -- studies. A Saudi Arabian study published in the 2011 "Asian Pacific Journal of Cancer Prevention" reported that lemon extract increased apoptosis, programmed cell death, in breast cancer cells in the laboratory.
Slowing Microbial Growth
Lemon extract could prove beneficial as a food preservative. Lemon extract slows the growth of bacteria and yeasts that cause food spoilage, according to an Italian study published in the August 2007 issue of "Journal of Food Protection."
Urinary Tract Stones
A Moroccan study published in the October 2007 issue of "BMC Urology" reported that lemon juice helped prevent kidney stone formation in rats. People with kidney stones often have recurrent attacks that cause pain, disability and possible damage to the urinary tract and kidney.
Essential oil compounds obtained from lemon extract, such as limonene, γ-terpinene and citral, might help reduce physical and psychological stress. Japanese researchers found that limonenes in particular inhibited serum corticosterone levels and cerebral monoamine levels, both indicators of stress in the brain. They reported their findings in the February 2008 issue of "Stress and Health."