GMO Tomatoes Promote Good Cholesterol

LOS ANGELESUCLA researchers have genetically engineered tomatoes to produce a peptide that mimics the actions of  high-density lipoprotein (HDL), known as "good" cholesterol, when consumed, according to a study published in the Journal of Lipid Research. Results found that mice fed these tomatoes in freeze-dried, ground form had less inflammation and plaque build-up in their arteries.

"This is one of the first examples of a peptide that acts like the main protein in good cholesterol and can be delivered by simply eating the plant," said senior author Dr. Alan M. Fogelman, executive chair of the department of medicine and director of the atherosclerosis research unit at the David Geffen School of Medicine at UCLA. "There was no need to isolate or purify the peptide it was fully active after the plant was eaten."

For the study, the team genetically engineered tomatoes to produce 6F, a small peptide that mimics the action of apoA-1, the chief protein in high-density lipoprotein (HDL) known as good" cholesterol. Scientists fed the tomatoes to mice that lacked the ability to remove low-density lipoprotein (LDL) known as "bad" cholesterol from their blood and readily developed inflammation and atherosclerosis when consuming a high-fat diet.

They found mice that ate the peptide-enhanced tomatoes, which accounted for 2.2% of their Western-style, high-fat diet, had significantly lower levels of inflammation; higher paraoxonase activity, an antioxidant enzyme associated with good cholesterol; higher levels of good cholesterol; decreased lysophosphatidic acid, a tumor- promoter that accelerates plaque build-up in the arteries in animal models; and less atherosclerotic plaque.

Several hours after the mice finished eating, the intact peptide was found in the small intestine, but no intact peptide was found in the blood. According to researchers, this strongly suggests that the peptide acted in the small intestine and was then degraded to natural amino acids before being absorbed into the blood, as is the case with the other peptides and proteins in the tomato.

"It seems likely that the mechanism of action of the peptide-enhanced tomatoes involves altering lipid metabolism in the intestine, which positively impacts cholesterol," said the study's corresponding author, Srinavasa T. Reddy, a UCLA professor of medicine and of molecular and medical pharmacology.

Previous studies performed by Fogelman's lab and other researchers around the world in animal models of disease have suggested that a large number of conditions with an inflammatory componentnot just atherosclerosismight benefit from treatment with an apoA-1 mimetic peptide, including Alzheimer's disease, ovarian and colon cancer, diabetes, asthma, and other disorders. The researchers said if the work in animal models applies to humans, consuming forms of genetically modified foods that contain apoA-1related peptides could potentially help improve these conditions.