A Randomized Study of the Effects of Additional Fruit and Nuts Consumption on Hepatic Fat Content, Cardiovascular Risk Factors and Basal Metabolic Rate

Abstract

BackgroundFruit has since long been advocated as a healthy source of many nutrients, however, the high content of sugars in fruit might be a concern.ObjectivesTo study effects of an increased fruit intake compared with similar amount of extra calories from nuts in humans.MethodsThirty healthy non-obese participants were randomized to either supplement the diet with fruits or nuts, each at +7 kcal/kg bodyweight/day for two months. Major endpoints were change of hepatic fat content (HFC, by magnetic resonance imaging, MRI), basal metabolic rate (BMR, with indirect calorimetry) and cardiovascular risk markers.ResultsWeight gain was numerically similar in both groups although only statistically significant in the group randomized to nuts (fruit: from 22.15±1.61 kg/m2 to 22.30±1.7 kg/m2, p = 0.24 nuts: from 22.54±2.26 kg/m2 to 22.73±2.28 kg/m2, p = 0.045). On the other hand BMR increased in the nut group only (p = 0.028). Only the nut group reported a net increase of calories (from 2519±721 kcal/day to 2763±595 kcal/day, p = 0.035) according to 3-day food registrations. Despite an almost three-fold reported increased fructose-intake in the fruit group (from 9.1±6.0 gram/day to 25.6±9.6 gram/day, p<0.0001, nuts: from 12.4±5.7 gram/day to 6.5±5.3 gram/day, p = 0.007) there was no change of HFC. The numerical increase in fasting insulin was statistical significant only in the fruit group (from 7.73±3.1 pmol/l to 8.81±2.9 pmol/l, p = 0.018, nuts: from 7.29±2.9 pmol/l to 8.62±3.0 pmol/l, p = 0.14). Levels of vitamin C increased in both groups while α-tocopherol/cholesterol-ratio increased only in the fruit group.ConclusionsAlthough BMR increased in the nut-group only this was not linked with differences in weight gain between groups which potentially could be explained by the lack of reported net caloric increase in the fruit group. In healthy non-obese individuals an increased fruit intake seems safe from cardiovascular risk perspective, including measurement of HFC by MRI.Trial RegistrationClinicalTrials.gov NCT02227511

Prevention of metabolic diseases

“…There was no significant difference in the change in liver fat content between groups, as the liver fat content in both intervention groups remained virtually unchanged. Fasting insulin increased slightly in both groups, again with no difference between groups (15). …”

“…Agebratt et al (15) randomized 30 healthy, young, and largely normal weight Swedish university students to add either ~500 kcal/d of fruit or nuts to their habitual diet. The primary objective of the study was to investigate whether the substantial increase in sugar consumption in the fruit group would increase hepatic fat content and other markers of cardiovascular risk.…”

A Critical Review on the Role of Food and Nutrition in the Energy Balance

“…Nut-rich diets have been proved to provide positive effects, both on cardiovascular health (owing to their content of mono-and polyunsaturated fats, flavonoids and vitamins) and on body weight, BMI or waist circumference [24,192]. At present, the role of nuts in the regulation of energy balance has not been extensively studied; however, favorable effects have been reported by a couple of RCTs [51,193]. In particular, a 28% increase in DIT 5 h after a meal rich in walnuts and a~100 kcal higher BEE after 2 months of a nut-rich diet (independent of weight change) have been observed [193].…”

“…At present, the role of nuts in the regulation of energy balance has not been extensively studied; however, favorable effects have been reported by a couple of RCTs [51,193]. In particular, a 28% increase in DIT 5 h after a meal rich in walnuts and a~100 kcal higher BEE after 2 months of a nut-rich diet (independent of weight change) have been observed [193]. The role of peanuts is even more uncertain as, in a small RCT, the consumption of high-oleic peanuts increased DIT more than conventional peanuts, but similarly to controls consuming biscuits [194].…”

Fat-Referenced MRI: Quanitaive MRI for Tissue Characterizaion and Volume Measurement

“…This evaluation has however become outdated as both reference methods have been upgraded, and the water-fat swaps seen in paper I have become less common. The PSR algorithm has also been successfully used in a range of studies [32,[68][69][70][71][72][73][74][75][76][77][78]. These studies did not directly evaluate the performance of PSR.…”