A workshop on 'Dietary Sweetness-Is It an Issue?'

This report summarises a workshop convened by ILSI Europe on 3 and 4 April 2017 to discuss the issue of dietary sweetness. The objectives were to understand the roles of sweetness in the diet, establish whether exposure to sweetness affects diet quality and energy intake, and consider whether sweetness per se affects health. Although there may be evidence for tracking of intake of some sweet components of the diet through childhood, evidence for tracking of whole diet sweetness, or through other stages of maturity are lacking. The evidence to date does not support adverse effects of sweetness on diet quality or energy intake, except where sweet food choices increase intake of free sugars. There is some evidence for improvements in diet quality and reduced energy intake where sweetness without calories replaces sweetness with calories. There is a need to understand the physiological and metabolic relevance of sweet taste receptors on the tongue, in the gut and elsewhere in the body, as well as possible differentiation in the effects of sustained consumption of individual sweeteners. Despite a plethora of studies, there is no consistent evidence for an association of sweetness sensitivity/preference with obesity or type 2 diabetes. A multifaceted integrated approach, characterising nutritive and sensory aspects of the whole diet or dietary patterns, may be more valuable in providing contextual insight. The outcomes of the workshop could be used as a scientific basis to inform the expert community and create more useful dialogue among health care professionals.

Worldwide trends in dietary sugars intake.

Estimating trends in dietary intake data is integral to informing national nutrition policy and monitoring progress towards dietary guidelines. Dietary intake of sugars is a controversial public health issue and guidance in relation to recommended intakes is particularly inconsistent. Published data relating to trends in sugars intake are relatively sparse. The purpose of the present review was to collate and review data from national nutrition surveys to examine changes and trends in dietary sugars intake. Only thirteen countries (all in the developed world) appear to report estimates of sugars intake from national nutrition surveys at more than one point in time. Definitions of dietary sugars that were used include 'total sugars', 'non-milk extrinsic sugars', 'added sugars', sucrose' and 'mono- and disaccharides'. This variability in terminology across countries meant that comparisons were limited to within countries. Hence trends in dietary sugars intake were examined by country for the whole population (where data permitted), and for specific or combined age and sex subpopulations. Findings indicate that in the majority of population comparisons, estimated dietary sugars intake is either stable or decreasing in both absolute (g/d) and relative (% energy) terms. An increase in sugars intake was observed in few countries and only in specific subpopulations. In conclusion, the findings from the present review suggest that, in the main, dietary sugars intake are decreasing or stable. A consistent approach to estimation of dietary sugars intake from national nutrition surveys is required if more valid estimates of changes in dietary sugars intakes are required in the future.

The effects of sucrose on metabolic health: a systematic review of human intervention studies in healthy adults.

We systematically reviewed interventions substituting sucrose for other macronutrients in apparently healthy adults to assess impact on cardiometabolic risk indicators. Multiple databases were searched to January 2012 and abstracts assessed by 2 reviewers. Twenty-five studies (29 papers) met inclusion criteria but varied in quality and duration. Weaknesses included small subject numbers, unclear reporting of allocation, unusual dietary regimes, differences in energy intake, fat composition or fibre between conditions, unhealthy subjects, heterogeneity of results, and selective reporting. Insufficient data were available to draw reliable conclusions except with regard to the substitution of sucrose for starch, where effects on plasma lipids were inconsistent, mostly explicable by other factors, or nonsignificant. Based on fewer studies, there was little evidence for significant effects on plasma glucose or insulin. Sucrose substitution for starch up to 25% energy does not appear to have adverse effects on cardiometabolic risk indicators in apparently healthy adults. Furthermore, there is no consistent evidence that restricting sucrose in an isoenergetic diet would affect risk indicators, except perhaps in people with certain preexisting metabolic abnormalities. Larger, high-quality studies, lasting several months and studying a wider range of outcomes, are needed in order to provide evidence on which to base public health initiatives.

Is there a specific role for sucrose in sports and exercise performance?

The consumption of carbohydrate before, during, and after exercise is a central feature of the athlete's diet, particularly those competing in endurance sports. Sucrose is a carbohydrate present within the diets of athletes. Whether sucrose, by virtue of its component monosaccharides glucose and fructose, exerts a meaningful advantage for athletes over other carbohydrate types or blends is unclear. This narrative reviews the literature on the influence of sucrose, relative to other carbohydrate types, on exercise performance or the metabolic factors that may underpin exercise performance. Inference from the research to date suggests that sucrose appears to be as effective as other highly metabolizable carbohydrates (e.g., glucose, glucose polymers) in providing an exogenous fuel source during endurance exercise, stimulating the synthesis of liver and muscle glycogen during exercise recovery and improving endurance exercise performance. Nonetheless, gaps exist in our understanding of the metabolic and performance consequences of sucrose ingestion before, during, and after exercise relative to other carbohydrate types or blends, particularly when more aggressive carbohydrate intake strategies are adopted. While further research is recommended and discussed in this review, based on the currently available scientific literature it would seem that sucrose should continue to be regarded as one of a variety of options available to help athletes achieve their specific carbohydrate-intake goals.

Soft Drink Intake in Europe-A Review of Data from Nationally Representative Food Consumption Surveys.

Public health interest in reducing the intake of sugar-sweetened soft drinks has resulted in various guidelines and initiatives related to their consumption, together with an increase in availability and sales of low and no-sugars versions. The aim of this review was to gain insight regarding individual-level amounts and types of soft drinks consumed across the lifecycle as reported in nationally representative surveys in Europe. The review highlighted significant gaps and challenges regarding the availability of recent country-specific soft drink consumption data including heterogeneity in categorisations used in reporting soft drinks. Nonetheless, crude estimates of mean intake (across countries) indicated that total soft drinks and soft drinks with sugars was highest in adolescents and lowest in infants/toddlers and older adults. For infants/toddlers, crude mean intakes of soft drinks with reduced/no sugars were higher than soft drinks with sugars. The review also found that consumption of total soft drinks is decreasing with a shift to consumption of soft drinks with reduced/no sugars in replacement of sugars-containing soft drinks. This review provides valuable insight into what data are currently available on soft drink consumption in Europe with heterogeneity in categorisations, terminology, and definitions of soft drinks observed.

Warm-up effects on muscle oxygenation, metabolism and sprint cycling performance.

To investigate the effects of warm-up intensity on all-out sprint cycling performance, muscle oxygenation and metabolism, 8 trained male cyclists/triathletes undertook a 30-s sprint cycling test preceded by moderate, heavy or severe warm up and 10-min recovery. Muscle oxygenation was measured by near-infrared spectroscopy, with deoxyhaemoglobin ([HHb]) during the sprint analysed with monoexponential models with time delay. Aerobic, anaerobic-glycolytic and phosphocreatine energy provision to the sprint were estimated from oxygen uptake and lactate production. Immediately prior to the sprint, blood [lactate] was different for each warm up and higher than resting for the heavy and severe warm ups (mod. 0.94 ± 0.36, heavy 1.92 ± 0.64, severe 4.37 ± 0.93 mmol l(-1) P < 0.05), although muscle oxygenation was equally raised above rest. Mean power during the sprint was lower following severe compared to moderate warm up (mod. 672 ± 54, heavy 666 ± 56, severe 655 ± 59 W, P < 0.05). The [HHb] kinetics during the sprint were not different among conditions, although the time delay before [HHb] increased was shorter for severe versus moderate warm up (mod. 5.8 ± 0.6, heavy 5.6 ± 0.9, severe 5.2 ± 0.7 s, P < 0.05). The severe warm up was without effect on estimated aerobic metabolism, but increased estimated phosphocreatine hydrolysis, the latter unable to compensate for the reduction in estimated anaerobic-glycolytic metabolism. It appears that despite all warm ups equally increasing muscle oxygenation, and indicators of marginally faster oxygen utilisation at the start of exercise following a severe-intensity warm up, other energy sources may not be able to fully compensate for a reduced glycolytic rate in sprint exercise with potential detrimental effects on performance.

Comment on Moz-Christofoletti, M.A.; Wollgast, J. Sugars, Salt, Saturated Fat and Fibre Purchased through Packaged Food and Soft Drinks in Europe 2015-2018: Are We Making Progress? Nutrients 2021, 13, 2416.

The European soft drinks industry fully supports efforts to monitor nutrition composition of food products [...].

Lactate response to short term exercise with elevated starting levels.

A model that describes the blood lactate concentration (BLC) dynamics [BLC(t)] of a Wingate Anaerobic Test (WAnT) as a function of (a) BLC at the start of exercise (BLC(0)), (b) extra-vascular increase in lactate (A), (c) two corresponding velocity constants of appearance (k (1)) and disappearance (k (2)) of lactate into and out of the blood requires that BLC(0) is equal to resting BLC (BLC(rest)). We developed a model that considers an elevated BLC(0). 19 males performed WAnTs with warm-ups increasing (p < 0.001) BLC(0). The goodness of each individual fit improved (p < 0.05) if the difference between BLC(rest) and BLC(0) (DeltaBLC) was higher than 1.0 mmol l(-1). All differences between old and new model (p < 0.05) in A, k (1) and k (2) were interrelated with and increased with DeltaBLC (p < 0.05). The new model well describes BLC(t) and prevents substantial errors concerning lactate generation and dynamics if BLC(0) is elevated by more than 1.0 mmol l(-1).

Muscle oxygen saturation measured using "cyclic NIR signals" during exercise.

A new approach to measure muscle oxygen saturation (SmO(2)) using near infrared spectroscopy (NIRS) has been proposed in this paper. This approach exploits the cyclic NIRS signals seen during exercise which are often regarded as "movement artefacts". This new measure, which we term the "cyclic SmO(2)", has the potential to be less affected by the myoglobin which is traditionally believed to be indistinguishable from haemoglobin using NIRS techniques. The cyclic SmO(2) also has fewer assumptions than the conventional SmO(2) measured using time, phase and spatially resolved spectroscopy methods. In a cycling exercise study, NIRS measurements were made over the Vastus lateralis muscle of 11 subjects. In a light exercise protocol, the group mean of the conventional SmO(2) was 51.7 +/- 4.3% and that of the cyclic SmO(2) was 56.0 +/- 3.9%. It was immediately followed by a hard exercise protocol and the group mean of the conventional SmO(2) was reduced to 42.6 +/- 6.1% and that of the cyclic SmO(2) to 48.5 +/- 5.6%. The reduction agrees with the general expectation. The cyclic SmO(2) is a promising new measure of muscle oxygenation.

Amateur boxing: activity profile of winners and losers.

An activity profile of competitive 3 × 2-min novice-level amateur boxing was created based on video footage and postbout blood [La] in 32 male boxers (mean ± SD) age 19.3 ± 1.4 y, body mass 62.6 ± 4.1 kg. Winners landed 18 ± 11 more punches than losers by applying more lead-hand punches in round 1 (34.2 ± 10.9 vs 26.5 ± 9.4), total punches to the head (121.3 ± 10.2 vs 96.0 ± 9.8), and block and counterpunch combinations (2.8 ± 1.1 vs. 0.1 ± 0.2) over all 3 rounds and punching combinations (44.3 ± 6.4 vs 28.8 ± 6.7) in rounds 1 and 3 (all P < .05). In 16 boxers, peak postbout blood [La] was 11.8 ± 1.6 mmol/L irrespective of winning or losing. The results suggest that landing punches requires the ability to maintain a high frequency of attacking movements, in particular the lead-hand straight punch to the head together with punching combinations. Defensive movements must initiate a counterattack. Postbout blood [La] suggests that boxers must be able to tolerate a lactate production rate of 1.8 mmol · L-1 · min-1 and maintain skillful techniques at a sufficient activity rate.

A new method to measure local oxygen consumption in human skeletal muscle during dynamic exercise using near-infrared spectroscopy.

Near infrared spectroscopy (NIRS) can readily report on changes in blood volume and oxygenation. However, it has proved more problematic to measure real-time changes in blood flow and oxygen consumption. Here we report the development of a novel method using NIRS to measure local oxygen consumption in human muscle. The method utilizes the blood volume changes induced by the muscle pump during rhythmically contracting exercising skeletal muscle. We found that the saturation of the blood during the contraction phase was lower than that during the relaxation phase. The calculated oxygen drop was then divided by the contraction time to generate a value for the muscle oxygen consumption in the optical region of interest. As a test we measured the muscle oxygen consumption in the human vastus lateralis during exercise on a cycle ergometer by 11 trained male athletes (32 +/- 11 years old) at 40% and 110% peak aerobic power. We saw an increase from 13.78 micromol 100 g(-1) min(-1) to 19.72 micromol 100 g(-1) min(-1) with the increase in power. The measurements are theoretically exempt from usual NIRS confounders such as myoglobin and adipose tissue and could provide a useful tool for studying human physiology.

Effect of warm-up on run time to exhaustion.

It is not known whether warm-up protocols typically employed by athletes are beneficial to performance. The aim of this study was to investigate the effect of warm-up on a perimaximal run to exhaustion, VO2 kinetics, energy metabolism and running economy. Nine male distance runners ran to exhaustion at a speed corresponding to 105% maximal oxygen uptake (VO2max) after each of three different warm-up protocols: no warm-up (NW), jog warm-up (WM), or jog with strides (WH). Warm-up did not affect pre-run blood lactate concentration (BLC), BLC-increase (DeltaBLC), net oxygen consumption, or running economy. WH increased the amplitude of the primary VO2 response (mean (confidence intervals of difference); 4083 ml min(-1) vs. 3763 ml min(-1) (-638, -2)), with no change in the time constant; reduced the rate of BLC-increase (DeltaBLC-rate) (0.02 mmol l(-1) s(-1) vs. 0.03 mmol l(-1) s(-1) (0.003, 0.01)); reduced anaerobic lactic power (109 W vs. 141 W (13, 51)); reduced the relative anaerobic lactic energy contribution (7.0% vs. 9.1% (0.8, 3.4)) compared to NW. The reduction in anaerobic power associated with DeltaBLC-rate between NW and WH was significantly correlated with the increase in aerobic power associated with the primary amplitude (r=0.674, p<0.05). Despite these theoretically beneficial metabolic effects, WH did not significantly increase time to exhaustion vs. NW (290 s vs.316 s (-77, 43)) but might be considered in events where the winning margin is often small.