Diet, Exercise and Cardiovascular Health - Effects of Chinese Heart Healthy Diet on Blood Pressure Among People With High Cardiovascular Risk: a Parallel, Multicenter, Single-blind, Randomized Controlled Feeding Trial

The Chinese Heart Healthy Diet (CHH-diet) is a study in the DECIDE project (Diet, ExerCIse and carDiovascular hEalth), which includes five studies. The others are DECIDE - Exercise, DECIDE - Salt in Elderly, DECIDE - Obesity in Children, and DECIDE - Smart Living. The primary aim of this study is to evaluate the effects of CHH-diet in reducing blood pressure in Chinese adults with high cardiovascular risk. The corresponding null hypothesis is the mean systolic blood pressure of participants in CHH-diet group is equal to the mean systolic blood pressure of those in usual diet group. The secondary aims of this study are: 1) to evaluate the effect of CHH-diet on reducing the blood lipid, blood glucose and overall risk of cardiovascular and cerebrovascular diseases; 2) the influence of different cuisines on the intervention effect; 3) the influence of baseline blood pressure, blood glucose and lipid levels on the intervention effect; 4) the difference of the food preference between the two groups; 5) the effect of CHH-diet on intestinal flora, and the influence of intestinal flora on the effect of CHH-diet on blood pressure, fasting blood glucose and blood lipids.

Potential participants will be evaluated for eligibility at each center located in cities accordance with the four cuisines: Qingdao and Beijing (Shandong cuisine), Shanghai (Huaiyang cuisine), Guangzhou (Cantonese cuisine), and Chengdu (Szechuan cuisine). Two screening visits will be performed to identify eligible participants. At the first visit, participants will be asked several key questions about inclusion and exclusion criteria. At the second visit, a full questionnaire and measurement will be conducted to screen eligible participants. All eligible participants will participate in a 1-week run-in phase in which they will be fed with the usual diet in urban China. A participant will be excluded if failing to consume more than three meals for any reason. Participants who pass the run-in phase will be re-check the inclusion and exclusion criteria and then assigned 1:1 to receive CHH-diet or usual diet with the use of a central concealed randomization procedure (simple randomization), stratified by center and batch after the each baseline survey completed. At each center, participants will enter the randomization phase through 3-4 batches according to the feeding capacity of each center.

Four different recipes of CHH-diet have been developed according to four local cuisines: Shandong cuisine (Qingdao and Beijing), Huaiyang cuisine (Shanghai), Cantonese cuisine (Guangzhou), and Chengdu (Szechuan cuisine), but the four different healthy recipes share the same nutrients targets. The control group will receive local usual diet with the similar 4-week menus as CHH-diet group, but their nutrients targets will be the same as run-in period. We will measure the actual intake of every meal for all participants during the whole study period to better estimate their nutrients intakes. All subjects will be advised to avoid outside food during the study period, and the information outside food should be reported if they eat.

Intake of foods and nutrients measurement: First, for each food/dish, raw food materials will be weighted after cleaning and before cooking. Then before the food served to the study participants it will also be weighted and recorded. After each meal, the leftover food from each participant will be measured and recorded as well. The average daily energy and dietary nutrient intake by each participants will be calculated using the China Food Composition (2nd Edition, volume 1).

The baseline data collection should be performed on the last two days of the run-in phase, which includes a questionnaire interview on demography, lifestyle and health behaviors, history of diseases, medication use (antihypertensive drugs, antidiabetic drugs, and lipid-lowering drugs), food preference; physical examinations (blood pressure, body weight & height, pulse rate); fasting blood tests (fasting glucose [FBG], total cholesterol [TC], low-density lipoprotein cholesterol [LDL-C], high-density lipoprotein cholesterol [HDL-C], triglycerides, and serum potassium); spot urine tests (sodium, potassium, creatinine excretion); and fecal sample tests on gut microbial community. The same physical examinations, medication use, food preference, fasting blood tests, spot urine tests, physical examinations and fecal sample tests on microbiome will be repeated at the end of the trial with the same methods by staffs blinded to the intervention. In addition, blood pressure, body weight, medication use, food preference assessment will be assessed weekly during the trial.