Variations in certain macronutrients may be correlated to change in insulin sensitivity/resistance.
The incidence of childhood obesity in North America has increased substantially in recent years. Childhood obesity has been linked to increased incidence of prediabetes and/or type 2 diabetes later in life. This information highlights the urgent need for effective preventative strategies that can be implemented in youth to decrease the likelihood of developing prediabetes or type 2 diabetes later in life. There is some evidence to suggest that fat ingestion may variably affect insulin sensitivity later in life depending on the type of fat ingested. Still other evidence points to a preservative effect of high fiber intake on insulin sensitivity. However, most studies on the effect of dietary intake on insulin sensitivity or glycemic response are relatively short in duration and even fewer are prospective. This study aims to assess the effect of various food groups and macronutrients on insulin sensitivity and secretion in a prospective manner over the course of 2 years.
This study is a prospective cohort in design and draws its participants from an ongoing longitudinal cohort termed the Quebec Adipose and Lifestyle Investigation in Youth (QUALITY). Potential participants were considered for inclusion if they were within the geographical catchment area (attending elementary school at one of 3 centers in Quebec, Canada), between the ages of 8 and 10, had both parents who were willing to participate in the data collection process with at least 1 being clinically obese, and were Caucasian in race (the QUALITY study was observing the natural history of obesity and other cardiovascular risk factors in young Caucasians). No exclusion criteria were mentioned. The eligible participants were interviewed at an initial clinic visit, where education was provided about a food portion measurement kit. Average daily nutrient consumption was determined by averaging the results of three phone interviews, in which a licensed nutritionist asked the child about what and how much (as determined by the previously provided measurement kit) was eaten during the previous 24-hour period. The information was then confirmed with the child’s parents and then entered into the CANDAT software, which calculated individual nutrient and components. At baseline, participants were given an oral glucose tolerance test (OGTT) as well as blood work (measuring plasma glucose and insulin concentrations) at 30, 60, 90, and 120 minutes after the start of the OGTT. This was repeated again at the close of the 2-year trial period. Data collected during the OGTT and corresponding bloodwork was used to calculate the Matsuda Insulin Sensitivity Index (ISI) and the homeostat model assessment of insulin resistance (HOMO-IR), research validated measures of insulin sensitivity, and resistance respectively. Change in the Matsuda IRI and the HOMO-IR were compared against average macronutrient consumption at baseline to determine if a correlation exists. Statistical significance was determined via analysis with linear regression models.
Overall, 564 children from the QUALITY trial were deemed eligible and included in this study. When the change in Matsuda ISI and HOMO-IR were compared against the dietary components (calculated at baseline), a 1.95% reduction in insulin sensitivity was observed for each increase of saturated fatty acids as a percentage of caloric intake (p<0.05). Conversely, each additional average serving of fruits and vegetables as well as additional average gram of fiber resulted in an increase in insulin sensitivity 2 years later (2.35 and 1.33% increase respectively, p<0.05 for both). No other nutrients appear to have any correlation with change in insulin sensitivity or resistance.
The results of this study suggest that increased intake of fruits, vegetables, and fiber correlate to decreased reductions in insulin sensitivity in children with a family history of obesity. This study also suggests that increased amounts of saturated fatty acids correlate to decreases in insulin sensitivity. Overall, this study highlights the importance of well-balanced meals and portion control with regards to prevention of type 2 and prediabetes in at-risk youth, as well as the need for more high-quality and broadly applicable diabetes prevention research.
- Increased intake of fruits and vegetables are correlated with decreased reductions in insulin sensitivity in youth with a family history of obesity.
- Increased saturated fatty acid intake is associated with reductions in insulin sensitivity in the same patient population.
- Recommending a well-rounded diet with emphasis on fruits, vegetables, and fiber intake as well as reduction of saturated fatty acids is a reasonable recommendation.
Van Hulst, Andraea, et al., “Lowering Saturated Fat and Increasing Vegetable and Fruit Intake May Increase Insulin Sensitivity 2 Years Later in Children with a Family History of Obesity.” The Journal of Nutrition, vol. 148, 2018, pp. 1838-1844. Doi: 10.1093/jn/nxy189.
Michael Zaccaro, Pharm. D. Candidate 2019, LECOM School of Pharmacy