Public release date: 7-Nov-2010
-the men who followed the olive oil diet lost an average of 12.4 pounds in an eight-week period
PROVIDENCE, RI – Researchers from The Miriam Hospital say a plant-based, olive oil diet similar to the Mediterranean diet can improve the health of men with recurrent prostate cancer.
The findings may be of significance to men who have been treated with androgen deprivation therapy (ADT), a common treatment that blocks the level of circulating androgens (male hormones), which can fuel the growth of prostate cancers. This therapy has been associated with increased body mass index, excess body fat around the waist and elevated insulin levels – all symptoms of metabolic syndrome. Metabolic syndrome increases the risk of heart disease, stroke and diabetes.
According to Miriam researchers, the men who followed the olive oil diet lost an average of 12.4 pounds in an eight-week period. As a result of the diet and weight loss, participants also experienced a significant improvement in some of the risk factors of metabolic syndrome, particularly triglyceride levels (a type of fat found in the blood that can cause plaque buildup in artery walls).
The findings were presented today at the American Dietetic Association’s 2010 Food & Nutrition Conference & Expo in Boston.
“My plant-based olive oil diet is based on foods that research suggests will improve health, such as vegetables, nuts and olive oil, so it is a healthy diet for weight loss,” says lead author Mary Flynn, PhD, RD, LDN, a research dietitian at The Miriam Hospital. “Our study shows that the diet was not only successful as a weight loss tool for these men, but our participants liked the diet and planned to stay on it.”
According to the American Heart Association, metabolic syndrome is characterized by a group of metabolic risk factors in one person. These include abdominal obesity, blood fat disorders (including high triglycerides, low HDL cholesterol and high LDL cholesterol), elevated blood pressure, and insulin resistance or glucose intolerance (excessive fat tissue in and around the abdomen). Metabolic syndrome has become increasingly common in the United States, and it’s estimated that more than 50 million Americans are affected by it.
Extra virgin olive oil has been shown to decrease blood pressure, fasting insulin, glucose, oxidation and inflammation – all risk factors for heart disease and some cancers. Not only does extra virgin olive oil improve the taste of the meal, but because it’s a healthy fat, it also keeps the stomach fuller longer, so individuals are less likely to snack between meals. According to Flynn, the health benefits of olive oil start at about two tablespoons per day.
The health benefits of a plant-based diet are due to the phytonutrients found in plant products. In particular, carotenoids, which are found in dark vegetables, have been shown to help decrease the risk of cancer. Studies also have shown that olive oil – the only oil that is from a fruit – has numerous phytonutrients that can improve health; it has been associated with decreasing oxidation, inhibiting tumors from forming or growing and decreasing inflammation. Research also suggests that about two tablespoons a day will improve insulin function and lower blood pressure.
The Miriam study included 11 men treated with ADT who developed metabolic syndrome. For eight weeks, they followed a plant-based olive oil diet, which included a minimum of three tablespoons of extra virgin olive oil daily, as well as four servings of vegetables a day. Nuts were allowed and poultry and seafood were limited to eight ounces a day. Men also kept daily food records for key food items and were asked to keep three-day food diaries at weeks four and eight. Participants’ weight loss goal was five percent of their baseline weight.
In addition to shedding an average of 12.4 pounds, men in the study lost an average of just over two inches in their waistline. They also experienced significant improvements in their triglyceride levels. At the start of the study, the average triglyceride level was more than 100 mg/dl; after eight weeks, it dropped down to a healthy range of less than 100 mg/dl.
“It’s possible that someday we may be able to recommend a diet that will prevent the development of metabolic syndrome in men being treated for recurrent prostate cancer, which would greatly decrease their risk of heart disease,” said Flynn.
A separate study led by Flynn earlier this year also showed that a plant-based, olive oil diet produced greater weight loss in breast cancer survivors compared to a more traditional low-fat diet.
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