Dried fruit consumption: effects on cardiometabolic health and contributions to nutrient intakes and diet quality in U.S. adults
Open Access
- Author:
- Sullivan, Valerie
- Graduate Program:
- Nutritional Sciences
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- February 13, 2020
- Committee Members:
- Penny Margaret Kris-Etherton, Dissertation Advisor/Co-Advisor
Penny Margaret Kris-Etherton, Committee Chair/Co-Chair
Connie Jo Rogers, Committee Member
Muzi Na, Committee Member
David Nathan Proctor, Outside Member
Kristina Susan Petersen, Special Member
Laura E Murray-Kolb, Program Head/Chair - Keywords:
- dried fruit
cardiometabolic
crossover trial
NHANES - Abstract:
- Suboptimal fruit intakes contribute to the burden of cardiometabolic diseases in the US. One potential strategy to increase fruit intakes and, thereby, health is to encourage consumption of dried fruits, which avert several barriers to consuming fresh fruit. Therefore the purpose of this dissertation was to investigate the effects of dried fruit consumption on cardiometabolic health and to characterize dried fruit consumption in US adults. These objectives were achieved by combining experimental and observational research methods. First, a randomized, crossover trial was conducted to determine the effect of consuming mixed dried fruits (plums, figs, dates, and raisins; 3/4 cup/day) for four weeks, compared to calorie- and carbohydrate-matched snacks, on risk factors for cardiometabolic disease in adults at elevated risk of cardiometabolic diseases (n=55). Participants were instructed to consume one serving of fresh fruit daily and to incorporate the study foods into their usual self-selected diets, substituting them for foods of comparable caloric value (~300 kcal) to support weight maintenance. The primary outcome was LDL-C; other outcomes included blood pressure, arterial stiffness, measures of glycemic control, and other lipids/lipoproteins. LDL-C did not differ between conditions but increased from baseline (3.9 mg/dL, 95% CI: 0.3, 7.6) after the dried fruit condition, whereas the increase was non-significant (2.1 mg/dL, 95% CI: -1.5, 5.7) after the control. Non-HDL-C (4.6 mg/dL, 95% CI: 0.3, 9.0) and LDL particle number (51 nmol/L, 95% CI: 1, 101) also increased (all P<0.05) after dried fruit consumption, while small LDL particles increased after the control condition (63 nmol/L, 95% CI: 11, 115; P<0.05). Dried fruits increased fasting glucose compared to the control (mean difference 1.5 mg/dL, 95% CI: 0.1, 2.9; P=0.038). Blood pressure, arterial stiffness, and CRP did not differ between-conditions. Weight increased in both conditions (control: 0.4 kg, 95% CI: 0.01, 0.75, P=0.043; dried fruit: 0.3 kg, 95% CI: -0.09, 0.65, P=0.14) with no between-condition difference in weight gain (P=0.55). The second study was a cross-sectional analysis of data from the National Health and Nutrition Examination Survey (NHANES), 2007-16. Dried fruit intakes and dietary sources were assessed in non-pregnant, non-lactating adults (age ≥20 years) with at least one complete dietary recall (n=25,590). Consumers of dried fruits were defined as individuals who consumed ≥1/4 cup-equivalent of dried fruit on at least one of two dietary recalls (n=3,785). A pseudo crossover analysis assessed the nutritional contribution of dried fruits to individuals’ diets by calculating within-person differences in nutrient and food group intakes on days when dried fruits were consumed versus not consumed (n=1,222). Mean dried fruit intakes were low (0.04 ± 0.001 cup-equivalents/day) and represented 3.6% of total fruit intakes. Plain dried fruits were the primary dietary source (49%), followed by cereals (19%) and sweets (12%). Consumers of dried fruits had lower mean BMI (-0.8 kg/m2, 99%: -1.5, -0.2), waist circumference (-2.6 cm, 99% CI: -4.3, -0.9,), and SBP (-1.8 mmHg, 99% CI: -3.3, -0.4), after adjusting for demographic and lifestyle factors (all P≤0.001). Consumers also had higher quality diets, with mean total HEI-2015 scores of 60.6 versus 52.6 (P<0.001) after adjustment for potential confounders. Intakes of total fruit, potassium, fiber, and total carbohydrates were greater on days when dried fruits were consumed versus not consumed (P<0.001). Polyunsaturated fat intake was also higher, which might be explained by greater intakes of nuts and seeds (both P<0.001). Total energy intakes were 205-209 kcal greater on days when dried fruits were consumed versus not (P≤0.002), suggesting that dried fruits did not displace other calorie sources. Together, the results of these studies suggest that consumption of dried fruits may increase total energy intake. In the clinical trial, participants gained weight after four weeks of daily dried fruit consumption. The observed weight gain indicated that the calories consumed from dried fruits did not completely displace other calories in participants’ usual diets, and so changes in cardiometabolic risk factors following dried fruit consumption in this trial might be partly attributable to the daily excess energy consumption. In adult NHANES respondents, calorie intakes were greater on days when dried fruits were consumed versus not consumed. Yet, US adult dried fruit consumers were, on average, healthier than non-consumers as evidenced by lower metrics of adiposity and SBP after controlling for several possible confounders. This suggests that dried fruits, in the amounts consumed by free-living adults in the US, do not adversely affect long-term energy balance and cardiometabolic health. Thus, dried fruits might help attain greater intakes of total fruit and shortfall nutrients but may contribute excess calories when consumed. Research is needed to inform what, if any, dietary guidance is needed to support maintenance of energy balance when dried fruits are incorporated into the diet.