If the findings hold up in a larger, longer study, they could have broad implications for the millions of people with high cholesterol.
Statin drugs are effective but costlier than adopting a strict vegetarian diet. Some patients cannot tolerate them, while others may prefer a non-drug approach.
The study was funded in part by the Canadian government and the Almond Board of California and was published in Wednesday's Journal of the American Medical Association.
It involved 46 men and women with high cholesterol levels. Sixteen ate the vegetarian diet for one month, 16 consumed a very low-fat diet, and 14 ate the low-fat diet and took 20 milligrams of lovastatin (sold as Mevacor) every day for a month.
The vegetarian group showed an average drop of 28.6 percent in their LDL cholesterol, the "bad cholesterol" that can raise the risk of heart disease. That was about equal to the 30.9 percent reduction seen in the low-fat diet plus statin group. By contrast, the low-fat diet-only group had just an 8 percent drop.
The vegetarian and statin groups had similar reductions in C-reactive protein, a blood marker of inflammation which in high levels increases heart disease risk, while a more modest effect was found in the low-fat diet-only group.
Further development of the diet studied "may provide a potentially valuable dietary option," said researchers led by Dr. David Jenkins and Cyril Kendall at the University of Toronto.
The fiber-rich vegetarian diet included eggplant, okra, soy protein, almonds, margarine containing plant sterols, barley and psyllium - foods that alone have been shown to have potentially beneficial effects on cholesterol.
The diet was prepackaged and provided to patients; whether people in a non-study setting would be as successful in following the strict diet is unclear, Dr. James Anderson of the University of Kentucky said in an accompanying editorial.
Still, Anderson said that if the results are confirmed in other rigorous studies, they could have "far-reaching implications for a large number of patients" by enabling them to lower their cholesterol without drugs.
By Lindsey Tanner