During the first stage, duly trained interviewers visited 8,000 households to gather information about healthy eating and lifestyle habits.

Participants were also asked to provide the following information and complete the following tests:

• Body weight, height, and waist circumference
• Blood pressure
• Electrocardiogram
• Lung function test (Spirometry)
• Blood test (fasting glucose, lipid profile, and creatinine). Blood samples were stored in ultrafreezers at -112°F (-80 ºC) to be used in future studies subject to participants’ consent.

Participants’ health is followed up on a regular basis.