Individual blood pressure responses to changes in salt intake: results from the DASH-Sodium trial.

Although group characteristics are known to influence average blood pressure response to changes in salt intake, predictability of individual responses is less clear. We examined variability and consistency of individual systolic blood pressure responses to changes in salt intake in 188 participants who ate the same diet at higher, medium, and lower (140, 104, 62 mmol/d) sodium levels for 30 days each, in random order, after 2 weeks of run-in at the higher sodium level. Regarding variability in systolic blood pressure changes over time, changes from run-in to higher sodium (no sodium level change) ranged from -24 to +25 mm Hg; 8.0% of participants decreased > or =10 mm Hg. Regarding variability in systolic blood pressure response to change in sodium intake, with higher versus lower sodium levels (78-mmol sodium difference), the range of systolic blood pressure change was -32 to +17 mm Hg; 33.5% decreased > or =10 mm Hg. Regarding consistency of response, systolic blood pressure change with run-in versus lower sodium was modestly correlated with systolic blood pressure change with higher versus medium sodium; systolic blood pressure change with higher versus lower sodium was similarly correlated with run-in versus medium sodium (combined Spearman r=0.27, P=0.002). These results show low-order consistency of response and confirm that identifying individuals as sodium responders is difficult. They support current recommendations for lower salt intake directed at the general public rather than "susceptible" individuals as one of several strategies to prevent and control adverse blood pressures widely prevalent in the adult population.

Food group sources of nutrients in the dietary patterns of the DASH-Sodium trial.

The aim of this paper is to identify major food group sources of several essential nutrients in the two dietary patterns used in the DASH-Sodium trial: a control diet and the DASH dietary pattern. The DASH-Sodium trial was a multicenter, randomized, controlled-feeding trial comparing the effects of three levels of sodium and two dietary patterns on blood pressure. Nutrient contents of all the menus for both the control and the DASH diets were analyzed and examined for their dietary sources from 13 food groups. Contributions of all foods within each food group to each nutrient were averaged then weighted to reflect the actual distribution of energy levels in the study. Nutrient contents across the three sodium levels are very similar within each diet. Refined grains and whole grains are the major energy sources for the control and the DASH diet, providing 35% and 23% to the total intake, respectively. Nutrient-dense whole grains contributed greatly, ranging from 11% to 46%, to the higher intakes of protein, fiber, calcium, magnesium, potassium, zinc, and folate in the DASH diet. Vegetables, in addition to being a good source for fiber, vitamins A, C, E, and folate, also contributed an average of 15% to the intakes of magnesium, potassium, and calcium in the DASH diet. Differences in nutrient contents between the control and the DASH diets were accomplished by varying the selection of food items (eg, refined grains vs whole grains) and quantities of certain food groups (eg, less red meats and higher amounts of fruits and vegetables). The DASH dietary pattern recommends four to five servings of fruits; four to five servings of vegetables; two to three servings of low-fat dairy products; seven to eight servings of grain products (preferably whole grains); two or less servings of meats, poultry, and fish per day; and four to five servings of nuts, seeds, and legumes per week for a 2,000 kcal diet. Each of these food groups contributes critical nutrients across various sodium levels. It is important to emphasize all food groups when trying to follow this proven dietary pattern.

Estimation of energy requirements in a controlled feeding trial.

BACKGROUND: Estimating energy requirements is a frequent task in clinical studies. OBJECTIVE: We examined weight patterns of participants enrolled in a clinical trial and evaluated factors that may affect weight stabilization. The Harris-Benedict equation and the FAO/WHO equation, used in conjunction with physical activity levels estimated with the 7-d Physical Activity Recall, were compared for estimating energy expenditure. DESIGN: This was a multicenter, randomized controlled feeding trial with participants of the Dietary Approaches to Stop Hypertension Trial. For 11 wk, the amount of food participants received was adjusted to maintain their body weights as close to their initial weights as possible. Change-point regression techniques were used to identify weight-stable periods. Factors related to achieving weight stabilization were examined with logistic regression. RESULTS: A stable weight was achieved by 86% of the 448 participants during the run-in period and by 78% during the intervention period. Energy intake averaged 11 +/- 2.4 MJ/d (2628 +/- 578 kcal/d), with most participants (n = 270) requiring 9-13 MJ/d (2100-3100 kcal/d). The difference between predicted and observed intakes was highest at high estimated energy intakes, mainly because of high and probably incorrect estimates of the activity factor. Participants with lower energy intakes tended to need less adjustment of their energy intakes to maintain a stable weight than did participants with higher energy intakes. CONCLUSIONS: Weight stabilization is not affected by diet composition, sex, race, age, or baseline weight. Either the Harris-Benedict equation or the FAO/WHO equation can be used to estimate energy needs. Activity factors > 1.7 often lead to overestimation of energy needs.

A 9-mo randomized clinical trial comparing fat-substituted and fat-reduced diets in healthy obese men: the Ole Study.

BACKGROUND: Dietary fat has been implicated as a risk factor for cardiovascular disease and obesity. OBJECTIVE: We evaluated the effect on body weight, body fat, lipids, glucose, and insulin of replacing dietary fat with olestra in moderately obese men. DESIGN: Forty-five healthy overweight men were randomly assigned to 1 of 3 diets: control diet (33% fat), fat-reduced diet (25% fat), or fat-substituted diet (one-third of dietary fat replaced by olestra to achieve a diet containing 25% metabolizable fat). Body fat was measured by dual-energy X-ray absorptiometry and visceral and subcutaneous abdominal fat by computed tomography. RESULTS: Thirty-six men completed the 9-mo study. Body weight and body fat in the fat-substituted group declined by a mean (+/- SEM) of 6.27 +/- 1.66 and 5.85 +/- 1.34 kg, respectively, over 9 mo compared with 3.8 +/- 1.34 and 3.45 +/- 1.0 kg in the control group and 1.79 +/- 0.81 and 1.68 +/- 0.75 kg in the fat-reduced diet group. At 9 mo, the mean difference in body fat between the fat-reduced and fat-substituted groups was -4.19 +/- 1.19 kg (95% CI: -6.57, -1.81), that between the control and fat-substituted groups was -2.55 +/- 1.21 kg (-0.13, -4.97), and that between the control and fat-reduced groups was 1.63 +/- 1.18 kg (3.96, -0.70). The men eating the fat-reduced diet asked for almost no extra foods, in contrast with the significantly higher requests (P < 0.05) from both of the other 2 groups. CONCLUSION: Replacement of dietary fat with olestra reduces body weight and total body fat when compared with a 25%-fat diet or a control diet containing 33% fat.