Milk Consumption and the Metabolic Syndrome in Menopausal Women

The proposed research will be undertaken as a randomized, cross-over, nutritionally controlled study, with participants being subjected to two 6-week isocaloric diets separated by a 4-week washout period. No stratification was considered since the population recruited will be relatively homogeneous. The experimental diet (designed as 'Milk') will be formulated so that the percentage of daily calories from fat (30%), saturated fat (10%), carbohydrates (55%) and proteins (15%) will conform to most of the dietary recommendations of the American Heart Association and the NCEP for primary prevention of CVD, with the exception of saturated fats (slight excess) and fibers (slight deficit). The cholesterol content of the experimental diet will not exceed 200 mg/day. The only source of dairy products during the experimental phase will be from 2% fat milk. We have chosen to use 2% fat milk because this is the most frequently consumed dairy product in Canada. Two percent fat milk also goes through minimal processing compared to milk or to other dairy products such as yogurt and cheese. Thus, bioactive components in milk are more likely to be retained in the 2% fat milk than in other more extensively processed products. The energy intake from milk will represent 20% of the consumed kcal/day. Based on a reasonable 2000 kcal/day regimen, a 20% intake attributable to 2% fat milk will correspond to 400 day/kcal, which will be derived from a 'daily dose' of 3 portions of milk/day. This dose has been shown to be effective in previous uncontrolled studies. The Control diet will be virtually identical in terms of menus, calories and macronutrient composition, with the exception that milk will be formally excluded from the regimen. The energy intake and changes in macronutrient composition attributable to the milk component in the experimental diet will be compensated in the control diet by modifying the protein, carbohydrate and lipid component of the various recipes.

A 4-week stabilization run-in period will precede the randomization of participants. During this run-in period, participants will be asked and instructed to comply to the NCEP-ATP III prudent diet. They will be asked to maintain their body weight constant during this period. Milk consumption will be adapted during this period to comply to the recommendations of NCEP-ATP III. The washout period between the two experimental diets will last 4 weeks and will also consist of NCEP-ATP III recommended diet. It must be stressed that foods will not be provided during the run-in and wash-out periods. These periods are imposed to minimize the inter- and intra-individual variability before and between the experimental phases.

Inclusion criteria

• Menopausal women (absence of menses > 12 months and FSH > 40 IU/ml), aged between 45 and 65 years
• Presenting 1 or more features of the MetS based on the NCEP-ATP III definition
• Average consumption of milk/dairy products fewer than 2 portions/d (≤ 1.9)
• Stable body weight (+/- 2 kg) for 6 months before the beginning of the study

Exclusion criteria

• Previous history of cardiovascular disease, type 2 diabetes and monogenic dyslipidemia
• Subjects taking medications for hyperlipidemia, hypertension or hormonal replacement therapy
• Endocrine disorders
• Smoking
• Food allergies, milk aversion or intolerant to lactose
• Women with extreme nutritional habits such as vegetarism or alcohol consumption > 2 drinks/day