- Click here for explanation of classification scheme.

The purpose of this study was to develop and test an exchange list Greek-Mediterranean diet that could be used in future clinical trials of breast cancer prevention. The hypothesis was that telephone counseling would result in large dietary changes because this type of counseling has been used in other studies that targeted increases in fruit and vegetable consumption.

• Women between the ages of 25 to 65 years were eligible
• Provided written informed consent
• In good overall health
• Currently a non-smoker
• In the normal to overweight range (BMI 18.5 to 30kg/m²)
• Had a diet with a fat intake of at least 23% of calories from seven-day food records with no more than 48% of fat intake being from MUFA
• Fruit and vegetable intakes considered as eligible were <5.5 servings per day, not including white potatoes and iceberg lettuce.

• Reported having a chronic disease such as diabetes mellitus, autoimmune disease or high blood pressure
• On a medically prescribed diet or taking dietary supplements >150% of Recommended Dietary Allowances
• Being pregnant or lactating or being treated with therapies or supplements that could obscure the ability to detect diet effects.

Recruitment

• Advertisements in community newspapers and at health fairs were used as well as flyers and employee newsletters
• Recruitment spanned April 2004 to August 2005.

 Design

Randomized controlled trial with a six-month diet intervention 

Blinding used

Not applicable

Intervention

• Subjects were randomized to the non-intervention (usual diet) or intervention diet (Modified Mediterranean Diet) for six months plus dietitian counseling weekly for the first three months and then biweekly thereafter
• Intervention goals were to decrease usual fat intakes by about half and to replace those fats with olive oil and other high-MUFA foods, increase fruit and vegetable servings to seven to nine servings per day, depending on energy intake, and consume at least one serving per day of culinary herbs and allium vegetables.
• Registered dietitians provided exchange goals and individualized telephone counseling, and diets were self-selected using a Mediterranean exchange list developed specifically for this study.

Statistical Analysis

• All analyses were carried out with SPSS v 15.0 with a significance level of 0.05
• Demographic characteristics of the two diet groups at baseline were compared by two-sample t-tests for continuous measures such as age, BMI, weight, waist circumference and X² tests
• Changes in dietary intakes from seven-day food records at each time point were modeled using repeated measures analysis of variance
• The correlation between the measurements at baseline, three months, and six months within each subject was modeled using a completely unstructured variance-covariance matrix thereby providing a robust option
• Post hoc tests used a Bonferroni correction protecting overall type I error at 5%.

 

Timing of Measurements

• All subjects filled out demographic questionnaires, were measured for weight and waist circumference and were asked to return seven-day food records at baseline, three months, and six months
• Height was measured at baseline only with a stadiometer to the nearest 0.5cm.

Dependent Variables

• Weight, BMI
• Waist circumference
• Change in diet (The change in diet was measured by seven-day food records and self-report)
• Food records were analyzed using the Nutrition Data System Research software from the University of Minnesota.

Independent Variables

• Non-intervention diet: Women assigned to this group did not receive any dietary counseling, if their intake of any vitamin or mineral was <67% of Recommended Dietary Allowances they were given a list of foods that are rich in that nutrient. The National Cancer Institute's Action Guide to Healthy Eating which emphasized fruits and vegetables, whole grains, and reduced fat intake was given to all women in this group.
• Intervention diet: Modified Mediterranean Diet. The diet goals were based on considerations of Greek intakes and on the types of foods available in the United States. The fruit and vegetable goal was seven to nine servings per day depending on energy intake and the fat intake goal that was both feasible and close to the Greek intakes was a PUFA:SFA:MUFA ratio of 1:2:5. To achieve change in the type of fat consumed, subjects were asked to choose "very lean" meats and "lean" meats from the exchange list and to limit meat intake overall. Registered dietitians determined exchange goals for each subject at the baseline visit. Participants received seven days of example menus for their own particular caloric and fat intake level. The intervention was implemented using telephone appointments and subjects were asked to mail or fax their self-monitoring records to the RD before the call. The counseling was weekly for the first three months and biweekly thereafter.

Control Variables

Demographic variables assessed through questionnaire

 

• Initial N: 69 women
• Attrition (final N): 60 women completed six months of participation
  • 33 in the control arm
  • 27 in the intervention arm
• Age: Mean age 44 years (range 25 to 59 years)
• Ethnicity: Not described
• Other relevant demographics: Not reported
• Anthropometrics: Mean BMI of enrolled women was 24 (range=19 to 30)
• Location: University of Michigan, Ann Arbor.

 

Key Findings

• Counseling using the Mediterranean exchange list was effective for large dietary changes relative to non-intervention group. There were statistically significant differences between the groups at three and six months, indicating an intervention effect.
• Repeated measures ANOVA indicated a statistically significant 48% increase in the dietary monounsaturated fat with no appreciable change in total fat intake, as well as a significant increase in fruit and vegetable intake from 4.0 to 8.6 servings per day (P<0.05)
• Compared to the non-intervention group, the Mediterranean group had a significantly higher intake of MUFA, fruit, vegetables, a-tocopherol, lutein, lycopene, a-carotene, B-carotene, and B-cryptoxanthin when averaged over time
• The intervention was successful in increasing categories of fruit and vegetables that were targeted by the exchange list. Specifically, while beta carotene is found in most fruits and vegetables, lutein is high in dark green vegetables and herbs, alpha carotene in dark orange vegetables, lycopene in tomatoes, and B-cryptoxanthin and vitamin c are high in many fruits.
• Total fat intake and percentage of energy from fat did not change substantially in the Mediterranean group, although the percentage of energy from fat did increase slightly
• PUFA and SFA intakes decreased by about 30% and MUFA intake increased by 45%. Changes in these fat intakes were evident at three months and were maintained to six months. This indicates that the targeted fat intakes were largely met in the Mediterranean group using the exchange list diet. 

 

 

 

The exchange list allowed women to meet the study goals while giving them flexibility in food choices within the food exchange categories. This self-selected diet may be useful for interventions that seek to decrease cardiovascular and cancer risks, and for people seeking to follow a Mediterranean style of eating using Western foods.

Government:	American Institute for Cancer Research Grant no. 03B043, NIH, GCRC at University of Michigan
Not-for-profit	Chemistry Laboratory of the Michigan Diabetes Research and Training Center

The authors did note some limitations to this study. Limitations of the intervention design include its small size, lack of specific goals for foods high in n-3 fatty acids that were quite high in traditional Greek diets, the short frame of the study, and the fact that waist measures were performed by multiple observers. The approach could be further modified for subsequent studies, and the optimal extent of counseling determined. With longer studies, dietary changes may become more automatic and therefore easier to maintain without as much record-keeping.