Hypertension constitutes a relevant public health matter and contributes to the occurrence of both stroke and coronary heart disease. In Australia, the incidence of hypertension was lately reported to be nearly 29 per cent. Moreover, hypertension accounts for 6.1 per cent of the total problems managed in general practice. During the last twenty years the number of obese people in Australia has more than doubled, and almost 60 per cent of adult citizens have been estimated to be either overweight or obese. There is a direct positive connection between overweight and hypertension: it has been estimated that the control of obesity may result in the reduction of 48 per cent of the hypertension in white people. Dietary sodium raises blood pressure (BP), while dietary potassium reduces the risk of hypertension and stroke. In a controlled interference research, a multifaceted dietary approach - Dietary Approaches to Stop Hypertension (DASH) that included a diet high in fruit, vegetables, and low-fat dairy products was proven to lead to considerable decreases in blood pressure. Hence, the objective of the current research was to discover the influence on blood pressure of a DASH-type weight loss diet (WELL diet) and to compare this with typical low-fat dietary advice (LF diet) in free-living persons who chose and prepared their own food.
Ninety four men took part in one screening appointment, and sixty three who met the preliminary criteria and wonted to take part in the program undertook baseline home blood pressure measurements for two weeks and later they then randomly assigned to either the LF or the WELL diet. Participants were seen twice at baseline, and commenced a 12-week interference research and were seen at weeks 2, 4, 8, and 12. Telephone contact was made with the participants at weeks 6 and 10. Clinical blood pressure, height, and weight were measured at baseline. Participants controlled their home blood pressure every day, for two weeks before being randomly assigned to 1 of the 2 diets.
The partakers completed a 24-h dietary record every fortnight on the day before their visit with the investigators. A food-frequency questionnaire was completed at baseline and at week 12 in order to evaluate standard consumption of fruit, vegetables, and dairy products. Participants were assisted with setting objectives for physical activity and diet. Dietary counseling was supervised by the coordinating dietitian and was offered by trained study personnel. The WELL diet was based on the DASH diet. This diet comprised advice to consume more than four servings of fruit or fruit juice [1 serving = 1 medium piece of fruit or fruit juice, more than four servings of vegetables [1 serving = 0.5 cup cooked vegetables, 1 cup salad vegetables, or 1 medium potato] and more than three servings of nonfat dairy products [1 serving = milk, yogurt, or cottage or ricotta cheese (0.5 cup)] daily. Fish was to be consumed more than three times weekly, legumes (1 serving = 1 cup cooked) at least once a week, and unsalted nuts and seeds four times weekly. Red meat was limited to no more than two servings weekly and fat to a maximum of four servings (4 teaspoons) a day. Participants were recommended to avoid butter, added salt (table or cooking), and obviously salty foods and to use lower-salt (<380 mg Na per 100 g) monounsaturated or polyunsaturated margarine. Those in the WELL group were given a complete dietary information booklet, recipes, and simple advice (tips).
The LF group was recommended to restrict their consumption of high-energy foods and beverages, decrease their saturated fat consumption, select mostly plant-based foods, consume nonfat or lowered-fat milk and yogurt, restrict their cheese and ice cream consumption to twice per week, choose lean meat, and avoid frying foods in fat. Specific objectives were not formulated. The ‘Healthy Weight Guide’ booklet issued by the National Heart Foundation of Australia (2002) was provided, along with the same recipes and tips as obtained by the WELL group. A maximum of four caffeine-containing beverages per day (for instance, cola drinks, coffee, and tea) and four standard (10 g alcohol) alcoholic beverages per week were allowed for both diet groups.
The major difference between the LF diet and the WELL diet was that the WELL diet had precise targets for fruit, vegetable, and dairy consumption, while the LF diet offered general guidelines concentrating on increasing fruit and vegetable consumption and lowering fat intake, especially saturated fat. All partakers were asked to take part in moderate-intensity exercise for more than thirty minutes on all or most days of the week.
Nine participants dropped out before finishing the research (four in the LF group and five in the WELL group); the participants who left did not vary considerably from the rest of the partakers with respect to age or body mass index (BMI). Eight of them found it too complicated to obey the study requirements, and one moved interstate. Of the fifty four men who managed to finish the research, eighteen were taking anti-hypertensive medicines (9 WELL, 9 LF).
The amount of time spent walking rose in both groups over the intervention period, with no considerable dissimilarities between the groups. At week 12, the WELL group observed a higher consumption of dairy products, however there was no important difference between the groups in fruit and vegetable consumption. Fruit consumption rose considerably in the course of the diet in comparison to baseline for both groups. For the WELL group only, intakes of dairy products and vegetables were considerably elevated in the course of the diet than at baseline. After adjustment for baseline dietary consumption, the 24-h dietary records suggested that the declines in dietary fat (g/d), saturated fat (g/d), percent of energy from fat, percent of energy from saturated fat, and sodium (mg/d) were higher in the WELL group than in the LF group, and the increases in the percent of energy from protein, percent of energy from carbohydrate, potassium (mg/d), calcium (mg/d), magnesium (mg/d), and phosphorus (mg/d) appeared to be higher in the WELL group than in the LF group.
Weight fell considerably in both groups by approximately 5 kg, with participants in the WELL, group losing 6 per cent of body weight and those in the LF group losing 5 per cent. The weight loss rate was not drastically different between both diet groups all through the research. The most significant decline in blood pressure in both groups was observed after four weeks of involvement. There was a more significant reduction in the WELL group than in the LF group in both systolic blood pressure (SBP) and diastolic blood pressure (DBP). Pulse rate also decreased by 3.8 [+ or -] 1.6 beats/min more in the WELL group. The percentage decline in SBP was 5.5 [+ or -] 1.0 per cent in the WELL group in comparison to 1.4 [+ or -] 0.9 per cent in the LF group. The percentage decline in DBP was 6.4 [+ or -] 1.1 per cent in the WELL group, in comparison to 1.0 [+ or -] 1.0 per cent in the LF group.
The current research scrutinized the influence on home blood pressure of 2 dietary interventions - one based on the DASH dietary pattern, and the other - a typical low-fat diet connected with greater physical activity to attain weight loss. The participants in both diet groups attained a weight loss of approximately 5 per cent to 6 per cent of body weight over three months. Those in the WELL group, though, had higher declines in SBP and DBP of approximately 5 mm Hg and 4 mm Hg, respectively. The groups were well matched at baseline for blood pressure and for the number of participanrs taking antihypertensive medicine (33 per cent in each group), even though BMI was at first one unit higher in the LF group than in the WELL group. This difference, though, is doubtful to have contributed to the raised effectiveness of the WELL diet with respect to blood pressure, due to the fact that there was no considerable difference in percentage weight loss between both groups.
The reason for the more significant decline in blood pressure with the WELL diet is unclear. There was no noteworthy difference between both groups in the change in blood lipids, even though those in the WELL diet group appeared to have a greater decrease in total fat, and especiaally in saturated fat consumption.
Some of the dietary differences between the WELL and the LF diet may explain some of the improved BP-lowering influence of the WELL diet, particularly, the increase in dietary potassium, which has been proven to reduce blood pressure by approximately 3 mm Hg systolic and 2 mm Hg diastolic. Dietary calcium and magnesium have also been weakly connected with lower blood pressure in population research, even though evidence for a BP-lowering influence in controlled interference research is not consistent. It appears, though, that a diet combining these nutrient changes - for instance, reduced sodium, saturated fat, higher potassium, calcium, magnesium, and phosphorus - within a diet, and a lot of exercise pattern that induces negative energy balance, attains a greater decline in blood pressure than a low-fat diet.
The findings of the current research clearly demonstrate that targeted dietary advice, combined with advice to walk >0.5 hour on most days of the week brought about a 5 per cent weight loss, an 8 mm Hg decrease in SBP, and a 5 mm Hg decline in DBP over three months. Additionally, the research proved that a lifestyle intervention that can be effectively introduced by obese or overweight free-living persons leads to a greater decline in blood pressure than does the common general dietary advice to decrease fat consumption. The reason for the increased efficiency of this diet over the low-fat diet, in terms of blood pressure is unclear, however may be connected with the increases in potassium and calcium intakes.
