|dc.description.abstract||Both epidemiological and intervention studies consistently show that regular consumption of nuts protects against cardiovascular disease (CVD). This is likely due in part to improvements in diet quality with the addition of nuts. While a limited number of studies have investigated the effects of the addition of nuts to the habitual diet on diet quality, no studies have examined changes to both dietary patterns and nutrient displacement.
Therefore the study which is the basis of this project aimed to compare the long-term effects of nut consumption in comparison to two other high energy-dense snacks on nutrient profiles, energy compensation, nutrient displacement, and food group intake patterns in 102 healthy individuals.
The study used data from a randomised, controlled, parallel study which examined the effects of nut consumption on CVD risk factors and body weight. Participants were randomly allocated to receive daily portions of ~1100kJ/d of hazelnuts (42g), chocolate (50g), potato crisps (50g), or no snack food (control group) for 12 weeks. Food diaries, body composition, physical activity levels and diet quality were collected and analysed at baseline and week 12. Food items consumed were coded as either a meal or snack and categorized as one of 30 food groups. Total gram intake and energy derived from food groups were also determined. Energy and nutrient intakes from baseline and week 12 were analysed using Kai-culator and displacement values were calculated using a published equation.
There were no statistically significant changes in body composition, or physical activity levels from baseline to week 12 between groups, after adjusting for baseline value, sex, baseline age and baseline body mass index (BMI) (all P≥0.258). However, a significant improvement in diet quality was observed in the hazelnut group. Compared to all other groups, the percentage of total energy derived from monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) (all P≤0.010) was significantly higher at week 12 for the hazelnut group. In addition, vitamin E intake (all P≤0.001), and absolute amounts of MUFA (all P≤0.001) and PUFA (all P≤0.013) were significantly higher in the hazelnut group compared to the other intervention groups at week 12. On the other hand, saturated fatty acids (SFA) (all P≤0.001) and carbohydrate (CHO) (all P≤0.004) intakes were significantly lower in the hazelnut group compared to the other groups at week 12. When the diets were analysed for snacks and meals separately, the significant differences in nutrient profiles remained related to snacks, but not to meals. There were no statistically significant differences between the three snack groups for energy compensation and displacement for nutrients (all P≥0.132), with the exception of fibre which was over-compensated for in the chocolate group and hazelnut groups (655%, 105% respectively) and partially compensated for in the potato crisp (35%) (overall P=0.030). As expected, the intervention groups had significantly greater mean gram intake and percent contribution of energy derived from the food group the test product was allocated to (all P<0.001). The only other significant differences observed were a reduction in mean grams and energy contribution from meat alternatives in the hazelnut group (P=0.041), and bread-based dishes in the potato crisps group (P=0.008.
Our study supports the findings of previous nut interventions, reporting no adverse effects on body composition with the inclusion of a moderate amount (42 g/d) of nuts in the diet for twelve weeks. In addition, nut consumption significantly improved diet quality in a way that would be expected to improve CVD risk. Our study indicates that changes occur in the snacks rather than in meals. An important difference between the current study and previous research is that our study analysed changes in food groups with nut consumption. We identified limited significant changes in food group consumption for any of the interventions with the exception of the food group the test products were allocated to. Findings from this study suggest the addition of nuts to the habitual diet can induce favorable nutrient modifications, which could potentially reduce the risk of chronic diseases.||