An ad libitum NND produces weight loss and blood pressure reduction in centrally obese individuals. This trial was registered at www.clinicaltrials.gov as NCT01195610.

It has been suggested that the human gut microbiota can be divided into enterotypes based on the abundance of specific bacterial groups; however, the biological significance and stability of these enterotypes remain unresolved. Here, we demonstrated that subjects (n ‫؍‬ 62) 18 to 65 years old with central obesity and components of metabolic syndrome could be grouped into two discrete groups simply by their relative abundance of Prevotella spp. divided by Bacteroides spp. (P/B ratio) obtained by quantitative PCR analysis. Furthermore, we showed that these groups remained stable during a 6-month, controlled dietary intervention, where the effect of consuming a diet in accord with the new Nordic diet (NND) recommendations as opposed to consuming the average Danish diet (ADD) on the gut microbiota was investigated. In this study, subjects (with and without stratification according to P/B ratio) did not reveal significant changes in 35 selected bacterial taxa quantified by quantitative PCR (ADD compared to NND) resulting from the dietary interventions. However, we found higher total plasma cholesterol within the high-P/B group than in the low-P/B group after the intervention. We propose that stratification of humans based simply on their P/B ratio could allow better assessment of possible effects of interventions on the gut microbiota and physiological biomarkers.

On the basis of the abundance of specific bacterial genera, the human gut microbiota can be divided into two relatively stable groups that might have a role in personalized nutrition. We studied these simplified enterotypes as prognostic markers for successful body fat loss on two different diets. A total of 62 participants with increased waist circumference were randomly assigned to receive an ad libitum New Nordic Diet (NND) high in fiber/whole grain or an Average Danish Diet for 26 weeks. Participants were grouped into two discrete enterotypes by their relative abundance of Prevotella spp. divided by Bacteroides spp. (P/B ratio) obtained by quantitative PCR analysis. Modifications of dietary effects of pre-treatment P/B group were examined by linear mixed models. Among individuals with high P/B the NND resulted in a 3.15 kg (95% confidence interval (CI): 1.55; 4.76, P<0.001) larger body fat loss compared with ADD, whereas no differences was observed among individuals with low P/B (0.88 kg (95% CI: −0.61; 2.37, P=0.25)). Consequently, a 2.27 kg (95% CI: 0.09; 4.45, P=0.041) difference in responsiveness to the diets were found between the two groups. In summary, subjects with high P/B ratio appeared more susceptible to lose body fat on diets high in fiber and whole grain than subjects with a low P/B ratio.

Which diet is optimal for weight loss and maintenance remains controversial and implies that no diet fits all patients. We studied concentrations of fasting plasma glucose (FPG) and fasting insulin (FI) as prognostic markers for successful weight loss and maintenance through diets with different glycemic loads or different fiber and whole-grain content, assessed in 3 randomized trials of overweight participants. After an 8-wk weight loss, participants in the DiOGenes (Diet, Obesity, and Genes) trial consumed ad libitum for 26 wk a diet with either a high or a low glycemic load. Participants in the Optimal well-being, development and health for Danish children through a healthy New Nordic Diet (OPUS) Supermarket intervention (SHOPUS) trial consumed ad libitum for 26 wk the New Nordic Diet, which is high in fiber and whole grains, or a control diet. Participants in the NUGENOB (Nutrient-Gene Interactions in Human Obesity) trial consumed a hypocaloric low-fat and high-carbohydrate or a high-fat and low-carbohydrate diet for 10 wk. On the basis of FPG before treatment, participants were categorized as normoglycemic (FPG <5.6 mmol/L), prediabetic (FPG 5.6-6.9 mmol/L), or diabetic (FPG ≥7.0 mmol/L). Modifications of the dietary effects of FPG and FI before treatment were examined with linear mixed models. In the DiOGenes trial, prediabetic individuals regained a mean of 5.83 kg (95% CI: 3.34, 8.32 kg; < 0.001) more on the high- than on the low-glycemic load diet, whereas normoglycemic individuals regained a mean of 1.44 kg (95% CI: 0.48, 2.41 kg; = 0.003) more [mean group difference: 4.39 kg (95% CI: 1.76, 7.02 kg); = 0.001]. In SHOPUS, prediabetic individuals lost a mean of 6.04 kg (95% CI: 4.05, 8.02 kg; < 0.001) more on the New Nordic Diet than on the control diet, whereas normoglycemic individuals lost a mean of 2.20 kg (95% CI: 1.21, 3.18 kg; < 0.001) more [mean group difference: 3.84 kg (95% CI: 1.62, 6.06 kg); = 0.001]. In NUGENOB, diabetic individuals lost a mean of 2.04 kg (95% CI: -0.20, 4.28 kg; = 0.07) more on the high-fat and low-carbohydrate diet than on the low-fat and high-carbohydrate diet, whereas normoglycemic individuals lost a mean of 0.43 kg (95% CI: 0.03, 0.83 kg; = 0.03) more on the low-fat and high-carbohydrate diet [mean group difference: 2.47 kg (95% CI: 0.20, 4.75 kg); = 0.03]. The addition of FI strengthened these associations. Elevated FPG before treatment indicates success with dietary weight loss and maintenance among overweight patients consuming diets with a low glycemic load or with large amounts of fiber and whole grains. These trials were registered at clinicaltrials.gov as NCT00390637 (DiOGenes) and NCT01195610 (SHOPUS), and at ISRNCT.com as ISRCTN25867281 (NUGENOB).