Dietary sugars intake and micronutrient adequacy: a systematic review of the evidence

Guidelines for sugars intake range from a population mean of less than 10 % energy from free sugars, to a maximum for individuals of 25 % energy from added sugars. The aim of the present review was to examine the evidence for micronutrient dilution by sugars and evaluate its nutritional significance. From a web-based search of MEDLINE and hand search of linked papers, forty-eight relevant publications were identified on sugars (total sugars, non-milk extrinsic sugars, or added sugars) or sugar-containing drinks. These included five reports from expert committees, six reviews, thirty-three observational studies and four small-scale interventions. There was inconsistency between studies as to the relationship between sugars intake (however expressed) and micronutrients. The statistical patterns varied between nutrients and population groups. Curvilinear associations were found in some analyses, with lower nutrient intakes at both extremes of sugar intake; however, factors such as dieting and under-reporting may confound the associations observed. Some studies found statistically significant inverse associations but these were weak, with sugars explaining less than 5 % of the variance. Mean intakes of most micronutrients were above the RDA or reference nutrient intake except among very high consumers of sugars. The available evidence does not allow for firm conclusions on an optimal level of added sugars intake for micronutrient adequacy and the trends that exist may have little biological significance except for a few nutrients (for example, Fe). It is established that energy intake is the prime predictor of micronutrient adequacy. A better understanding of valid approaches to energy adjustment, misreporting and the assessment of micronutrient adequacy is crucial to further progress in this area.