PROVIDENCE, RI Researchers from The Miriam Hospital have
found that olive oil may offer another potential health benefit it
produces greater weight loss in breast cancer survivors compared to
a more traditional low-fat diet.
The findings may be of significance to women with breast
cancer, since excess weight at the time of diagnosis, or even
moderate weight gain during cancer treatment, is associated with an
increased risk of cancer recurrence, particularly in
post-menopausal women.
In this pilot study, women followed two 1,500-calorie diets a
conventional low-fat diet recommended by the National Cancer
Institute (NCI) and a plant-based olive oil diet similar to the
Mediterranean diet. After eight weeks on each diet, participants
selected one diet to follow for an additional six months of
continued weight loss or weight management.
According to the findings, published in the June issue of the
Journal of Women’s Health, 80 percent of women who started with the
plant-based olive oil diet lost more than 5 percent of their
baseline weight, compared to 31 percent who started with the NCI
diet. But researchers were most surprised to find that after trying
both diets, most women chose to stick with the less conventional,
higher fat olive oil diet, saying they found the food more
appetizing, accessible and affordable.
Mary Flynn, PhD, RD, LDN, the study’s lead author and a
research dietitian at The Miriam Hospital, says many breast cancer
patients don’t realize there is a link between weight and cancer
recurrence.
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“That’s why it was important for us to compare these two
diets and determine which one the women not only enjoyed following,
but also produced the best weight loss, because that’s the diet
they’re more likely to stick with,” says Flynn. “In this case, it
was a diet enriched with extra virgin olive oil, which is a source
of healthy fats, and includes foods associated with improving one’s
health, such as vegetables, beans and other plant
products.”
Extra virgin olive oil has been associated with decreasing
breast cancer risk in Greece, Spain and Italy, where it is consumed
in great quantities. Many studies have also demonstrated the cancer
protective properties of carotenoids, a phytonutrient found in the
red, orange and yellow pigments of fruits and vegetables. The NCI
lists obesity as a risk factor for disease recurrence but does not
recommend a specific diet for weight loss, although it has
consistently recommended lowering dietary fat to prevent breast
cancer.
Flynn developed the olive oil diet used in the study, which
included at least three tablespoons of olive oil per day, with nuts
at breakfast. Women also ate three servings of fruit and unlimited
vegetables daily, and whole grains were also emphasized. Women
could eat limited amounts of poultry and fish per week but red meat
and polysaturated fats, like vegetable oils, were
prohibited.
Because the NCI-recommended low-fat diet is not as specific,
women had a less restrictive meal plan. Their diet consisted of at
least five servings of fruits and vegetables, approximately 25 to
50 grams of fat (including canola oil) and six to seven ounces of
lean meat (not red meat) daily.
The study included 44 overweight women (BMI of at least 25)
diagnosed with invasive breast cancer after the age of 50 who were
within four years after completing treatment. The order of the
diets was randomly assigned, and participants followed each diet
for eight weeks. Women were provided with meal plans and recipes
for each diet and were asked to keep three-day food diaries at
weeks four and eight of each diet and during months three and six
of the follow-up period. Weight was measured and blood samples were
taken at the end of each study period.
Overall, 28 of the 44 women completed both diets and 19 of
the 22 eligible for the six months of follow-up chose to follow the
plant-based olive oil diet. All 19 women either maintained their
weight loss or lost additional weight during this time.
“I found this surprising, particularly since the low-fat diet
is more commercial and more recognizable to women, so I thought the
preference would be more evenly split,” says Flynn, who is also an
assistant professor of medicine at The Warren Alpert Medical School
of Brown University. “But the women who enjoyed the olive oil diet
said not only were they losing weight but they weren’t as hungry.
That’s because they were advised to include fat in the form of
olive oil or nuts at each meal, so they weren’t as likely to snack
between meals, which can cause weight gain.”
As researchers expected, the plant-based olive oil diet also
resulted in lower triglycerides (a type of fat found in the blood)
and higher high-density lipoprotein cholesterol (HDL, or “good”
cholesterol). High triglycerides and low levels of HDL have both
been linked with increased cancer risk.
