Heart attacks and strokes are the crises we notice, but they result from a slow process of atherosclerosis, the hardening and clogging of the arteries with fatty substances called lipids. Immune cells stick to the walls of blood vessels, scavenge lipids, and multiply. The blood vessel walls inflame and thicken as the smooth muscle cells lining them change, swelling and dividing to create plaques, clogs, and warty growths called atheromas.

For a very long time, doctors and researchers assumed that the lipids came from eating fatty, cholesterol-rich food. But the research hasn't borne this out; some people who eat large amounts of the foods we thought were the sources of the fat, such as eggs, butter, fatty fish, and meat, don't necessarily develop heart disease.

UConn researchers believe they may have solved part of the puzzle. Using careful chemical analysis of atheromas collected from patients by a colleague at Hartford Hospital, they found lipids with a chemical signature unlike those from animals at all. Instead, these strange lipids come from a specific family of bacteria.

"I always call them greasy bugs because they make so much lipid. They are constantly shedding tiny blebs of lipids. Looks like bunches of grapes," on a bacterial scale, says Frank Nichols, a UConn Health periodontist who studies the link between gum disease and atherosclerosis. The bacteria, called Bacteroidetes, make distinctive fats. The molecules have unusual fatty acids with branched chains and odd numbers of carbons (mammals typically don't make either branched chain fatty acids or fatty acids with odd numbers of carbons).