The fruit is designed to mimic HDL, or good cholesterol, according to a news release.
The researchers found that even small amounts of a specific lipid in the small intestine can cause high cholesterol levels and inflammation that leads to clogged arteries.
Their work was published in the December issue of the Journal of Lipid Research.
Originally, scientists believed that the small intestine would just package fat and cholesterol from a high-fat, high-cholesterol diet for transport to the liver.
There, the high fat load was suspected to lead to increased blood levels of LDL, or bad cholesterol, and a decrease in good cholesterol levels.
But the UCLA group found that even 1 part per million of the lipids, known as LPAs, in the small intestine may play a larger role in atherosclerosis, or artery clogging, than previously suspected.
The genetically engineered tomatoes produce a small peptide called 6F that mimics the chief protein of the beneficial HDL.
The researchers added 2.2 percent by weight of freeze-dried tomato powder to mouse rations.
One group of mice were fed a low-fat, low-cholesterol diet whereas the other group ate a high-fat, high-cholesterol diet.
Regardless of the diet, the genetically engineered tomatoes prevented an increase of the bad peptides in the small intestine and halted the increase of bad cholesterol, decreases in good cholesterol and systemic inflammation.
Tomatoes that were not genetically engineered had no effect.
The next step is to identify the genes in the small intestine that are altered by the LPAs to find signaling pathways that may be treatment targets.