A new study conducted by Canadian scientists has found that a special vegetarian diet including soy, nuts, viscous & plant sterol, lowered bad cholesterol significantly, without the assistance of drugs, over a six month period. In fact, study participants on this diet showed a significantly greater lowering of bad cholesterol than those on an ordinary vegetarian diet of low-fat and whole grains, over the same period.
The new study, conducted by David J. A. Jenkins, M.D., of St. Michael’s Hospital and the University of Toronto, and colleagues, is published in the August 24/31, 2011 issue of JAMA, the journal of the American Medical Association.
The new study “represents the first randomized trial to our knowledge to assess the ability of an intervention that counsels for consumption of these cholesterol-lowering foods to reduce LDL-C at 6-month follow-up in real-world conditions,” the researchers wrote.
In the study, a group of 345 Canadian who volunteered for the study were selected to participate on the basis of having initially high levels of low-density lipoprotein cholesterol (“LDL-C” or bad Cholesterol), ranging from 135 to 205 mg/dL for the men in the study, and from 116 to 178 mg/dL for the postmenopausal women in the study. None of the participants had a personal or family history of cardiovascular disease, hypertension, or diabetes, and none of the participants were currently taking any cholesterol-lowering medications.
The participants were randomly divided into three groups — two “intervention groups” who went on the special vegetarian diet, high in soy protein, nuts, viscous, and plant sterols, and a control group who went on a vegetarian low-saturated fat diet with high fiber and whole grains, including whole grain cereals, fruit and vegetables, but not containing any of the four mentioned cholesterol-lowering foods (soy, nuts, viscous, and plant sterols). Over the six months of the study, one of the intervention groups (routine) received counseling in two one-hour visits, and the other intervention group (intensive) received seven such counseling visits.
According the the study report, the special foods selected for the intervention diet (soy, nuts, viscous and plant sterols) have previously been recognized by the U.S. Food & Drug Administration (FDA), based on prior studies, as being associated with lowering of cholesterol and improved heart health. “Many of these foods [also] have other attributes, including lowering the glyceimic index, which may aid in reducing disease risk for cardiovascular heart disease, diabetes, and obesity,” the researchers stated. However, according to the authors, the long-term effect of diets rich in these foods compared to conventional dietary advice had not previously been measured.
A sample of the special diet assigned to the intervention groups in the study, compared to the control group diet, is shown in a chart called “Representative Diets Followed in Control and Dietary Portfolio Treatment Groups,” that is linked with the published study report in JAMA.
Here is a sample of the foods included in the special cholesterol-lowering diet, provided by the study authors:
Snack ( all Snacks could be eaten with meals, if desired)
The researchers measured the LDL-C levels of the study participants at the beginning of the study, at each of their counseling visits, and at six months, to determine the effect of the assigned diets on the participants’ LDL-C cholesterol levels over six months.
The overall attrition rate of the participants was not significantly different between the three study groups (18 percent for intensive dietary group, 23 percent for routine dietary group, and 26 percent for control group).
The researchers found that at the end of six months on the assigned diets, the LDL-C cholesterol levels of those on the special cholesterol-lowing diet who received 7 counseling sessions (intensive group) were reduced by an average of 13.8 percent, the LDL-C cholesterol levels of those on the special diet who received two counseling sessions (routine group) were reduced by an average of 13.1 percent, and the LDL-C cholesterol levels of those in the control group were reduced by 3.0 percent.
“Percentage LDL-C reductions for each dietary portfolio were significantly more than the control diet,” the authors wrote. “The 2 dietary portfolio interventions did not differ significantly. Among participants randomized to one of the dietary portfolio interventions, percentage reduction in LDL-C on the dietary portfolio was associated with dietary adherence,” the researchers stated.
The special diet achieved these significant reductions in LDL-C (bad cholesterol), “without lowering HDL-C [good cholesterol],” according to the study authors.
The researchers also found that the intensive cholesterol-lowering diet let to a significant reduction in diastolic blood pressure of 2.1 mm Hg, compared with the control diet. In addition, the Cholesterol-lowering diet reduced the calculated 10-year cardiovascular heart disease risk by 11.3% in the intensive intervention dietary group, and by 10.8% in the routine intervention group, according to the study authors. These reductions were significantly greater than the .5% reduction in cardiovascular heart disease risk in the control group, the researchers found.
“In conclusion,” the authors wrote, “this study indicated the potential value of using recognized cholesterol-lowering foods in combination. We believe this approach has clinical application. A meaningful 13 percent LDL-C reduction can be obtained after only 2 clinic visits of approximately 60-and 40-minute sessions.”
The authors observed that upon joining the study the study participants, “were already consuming an acceptable background diet low in saturated fat and cholesterol.” Therefore, they further concluded “this approach may underestimate the effectiveness of the diet when applied to those individuals who are not already following therapeutic diets.”
Implications – Is Changing Your Diet Enough?
“A lot of people rely on the medication, but diet is really powerful actually,” Dr. Jenkins, the study’s lead author, who is a professor of nutrition and metabolism at University of Toronto, told Reuters Health. He suggested that doctors should encourage their patients with high cholesterol to try diet changes, if they’re interested, according to Reuters. “A couple of visits to a nutritionist might be enough for motivated patients to make the switch to a plant-based, higher-fiber diet,” he added.
“The diet only is enough for the majority of the people that have a not-so-good lifestyle,” Dr. Joan Sabate, head of nutrition at Loma Linda University in California (who was not involved in the study), told Reuters Health. “By changing the diet and their lifestyle they can establish good control of their cholesterol,” she said.
“The main takeaway here is that people can lower their cholesterol with diet if they put their minds to it,” Dr. Jenkins, lead author of the study, told ABC News. “These can be small changes. We’re not asking people to live behind bars,” he said.
The full study report is available in the August 24/31, 2011 issue of JAMA, the journal of the American Medical Association.
View a video interview with Dr. Jenkins, lead author of the study, which is linked from the JAMA study report »
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