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Eating in the lockdown during the Covid 19 pandemic; self-reported changes in eating behaviour, and associations with BMI, eating style, coping and health anxiety.
Coulthard, H, Sharps, M, Cunliffe, L, van den Tol, A
Appetite. 2021;161:105082
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The Covid-19 pandemic resulted in national lockdowns, which resulted in isolation within people’s homes. This cross-sectional survey examined changes in eating patterns and behaviour during lockdown. Of the 620 participants included in the study, eating higher energy density foods was more common in females with a higher BMI and higher health anxiety. Although there was a change in emotional eating behaviours across the sample as a whole, it was not in the expected direction, with many participants reporting a decrease in emotional eating after the implementation of lockdown. There were also increases in fruit and vegetable consumption and home prepared foods. Many of these behavioural responses were influenced by pre-lockdown tendencies. Therefore, it is important to consider these when understanding coping strategies during lockdown, and how to support clients as we come out of lockdown.
Expert Review
Conflicts of interest:
None
Take Home Message:
- National lockdowns, as seen during the 2020/21 Covid-19 pandemic, impacted eating behaviour and associations with BMI, eating style and health anxiety.
- Given the new nature of this research, it is not clear what impact confounding factors such as food insecurity had on changing eating behaviours.
- Disproportionate risks were seen in certain demographics and in those shielding due to their heightened risk from Covid-19.
- Retrospective and longitudinal studies to monitor the impact of lockdowns on eating behaviour and health anxiety are needed.
Evidence Category:
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A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
The role of eating behaviours and psychological responses during lockdown has become an area of interest, particularly with the uncertainty of going into future lockdowns. With Covid-19, and individual’s responses to it, being a relatively new research topic, there is not yet enough evidence for longitudinal outcomes of the findings in these studies. It is also difficult to ascertain the influence of confounding variables prior to the national lockdown, such as food insecurity, not accounted for due to the unpredictable start to the pandemic. There has also been disproportionate risks between certain demographics and their Covid-19 risk, therefore further research on the impact of this on health anxiety and subsequent eating behaviours is required. This highlights a wider need for continued research on the topic.
Clinical practice applications:
Those who had problematic eating behaviours and higher BMI pre lockdown will need to be supported with healthier coping practices if subsequent lockdowns occur, to prevent health related anxiety and consumption of high energy density foods. Furthermore, those who were shielding in their homes were also more likely to show an increase in emotional eating post lockdown. Therefore, clients who spent a large amount of lockdown shielding will need additional support, to develop coping strategies to prevent risk of emotional eating and health anxiety.
Considerations for future research:
Both retrospective and longitudinal studies monitoring the impact of eating behaviours and health anxiety pre and post lockdown are needed. This will help further the evidence base of the potential role of Covid-19 related health anxiety on eating patterns, coping strategies and dietary choices.
Abstract
The global coronavirus pandemic (Covid 19) resulted in national lockdowns where individuals were asked to isolate in their homes to stop the spread of the disease. Using a cross-sectional survey, the current paper aimed to examine self-reported changes in eating patterns and behaviour during the lockdown in the UK, and associations with BMI, demographic variables, eating styles, health anxiety, food insecurity and coping strategies. Participants (N = 620) were recruited online through social media advertising. The results showed that there were self-reported changes to food consumption during the lockdown across the sample. Increases in consumption of HED (high energy density) snack foods during the lockdown was associated with sex, pre-lockdown eating behaviour (emotional eating and uncontrolled eating), and Covid-specific health anxiety. Increases in positive eating practices such as eating more home prepared foods, and fruits and vegetables, were associated with adaptive coping strategies. Higher emotional eating (EE) during the lockdown was associated with a higher BMI, higher pre-lockdown EE and maladaptive coping strategies. Maladaptive coping strategies moderated the relationship between BMI and EE during the lockdown. In particular a higher BMI was associated with higher EE during the lockdown if an individual also had higher maladaptive coping strategies. These findings suggest that changes to eating behaviour may be part of a wider style of maladaptive or adaptive coping, particularly in those with a history of EE or uncontrolled eating. Preparing individuals to adopt more adaptive coping strategies during lockdown situations may be crucial to improving health during subsequent the lockdown events.
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Moderate Consumption of Beer (with and without Ethanol) and Menopausal Symptoms: Results from a Parallel Clinical Trial in Postmenopausal Women.
Trius-Soler, M, Marhuenda-Muñoz, M, Laveriano-Santos, EP, Martínez-Huélamo, M, Sasot, G, Storniolo, CE, Estruch, R, Lamuela-Raventós, RM, Tresserra-Rimbau, A
Nutrients. 2021;13(7)
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During the menopause, hormonal changes can trigger uncomfortable symptoms such as hot flashes, night sweats, sleep disturbances, and vaginal dryness. Hormone replacement therapy does reduce some of the symptoms, however there has been an increased interest in alternative therapies such as phytoestrogens to relieve these symptoms. Phytoestrogens are compounds with oestrogen-like properties naturally found in plants. Beer is the main food source of the strongest phytoestrogen identified to date. The aim of this six-month parallel, controlled clinical intervention trial was to evaluate if a moderate daily intake of beer, with or without alcohol, could reduce menopausal symptoms in women. Female sex hormone profile and cardiovascular risk factors (CVRF) were also monitored. 34 postmenopausal women took part. One group included alcoholic beer (AB), and a second group added non-alcoholic beer (NAB) for 6 months. The control group took no alcohol in this time. After a 6-month follow-up both groups (AB and NAB) significantly reduced the severity of the menopause-related symptoms. These results must be considered as preliminary and will require confirmation with larger sample sizes.
Abstract
The menopausal transition can be a challenging period for women's health and a trigger of uncomfortable symptoms. Beer is the main food source of isoxanthohumol, a precursor of 8-prenylnaringenin, the strongest phytoestrogen identified to date. As phytoestrogens are reported to reduce perimenopausal symptoms, we evaluated if a daily moderate consumption of beer with (AB) and without alcohol (NAB) could improve menopausal symptoms and modify cardiovascular risk factors. A total of 37 postmenopausal women were enrolled in a parallel controlled intervention trial and assigned to three study groups: 16 were administered AB (330 mL/day), 7 NAB (660 mL/day), and 14 were in the control group. After a 6-month follow-up of the 34 participants who finished the trial, both interventions (AB and NAB) significantly reduced the severity of the menopause-related symptoms (p-value AB vs. Control: 0.009; p-value NAB vs. Control: 0.033). Moreover, AB had a beneficial net effect on psychological menopausal discomforts compared to the control group. As the sex hormone profile did not differ significantly between the study groups, the effects of both types of beers (AB and NAB) are attributed to the non-alcoholic fraction of beer. Furthermore, moderate NAB consumption improved the lipid profile and decreased blood pressure in postmenopausal women.
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Consumption of a Beverage Containing Aspartame and Acesulfame K for Two Weeks Does Not Adversely Influence Glucose Metabolism in Adult Males and Females: A Randomized Crossover Study.
Kim, Y, Keogh, JB, Clifton, PM
International journal of environmental research and public health. 2020;17(23)
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Artificial sweeteners gained popularity in the past decade, especially in the food industry. Up until recently, people generally considered it a better option to decrease sugar consumption and reduce obesity and Type 2 Diabetes. This randomised crossover study looked at the adverse effects of two commonly used artificial sweeteners on normal-weight subjects, overweight and obese subjects. A total of 39 healthy subjects without Type 2 Diabetes participated in this study. For two weeks, participants consumed 0.6 litres of a commercially branded soft drink containing acesulfame K and aspartame to assess the effects of the ingredients on glucose homeostasis. During the two-week treatment period, the healthy subjects did not show any significant detrimental impact of artificially sweetened beverages on glucose, insulin and insulin sensitivity. However, the study population was small, and the study was conducted only for a relatively short period. Therefore, further, longer-term robust studies are required to estimate the significance of the detrimental effect of artificially sweetened beverages on glucose homeostasis. Nevertheless, this study can help healthcare practitioners understand the short-term impact of artificial sweeteners, keeping in mind that further research is needed to investigate the effects.
Abstract
There is an association between the consumption of artificial sweeteners and Type 2 diabetes in cohort studies, but intervention studies do not show a clear elevation of blood glucose after the use of artificial sweeteners. The objective of this study was to examine whether two commonly used artificial sweeteners had an adverse effect on glucose control in normal-weight subjects, and in overweight and obese subjects when consumed for 2 weeks. In the study, 39 healthy subjects (body-mass index, kg/m2) (18-45) without Type 2 diabetes with an age of 18-75 years were randomly assigned to 0.6 L/day of an artificially sweetened soft drink containing acesulfame K (950) and aspartame (951) or 0.6 L/day of mineral water for 2 weeks each in a crossover study. There was a 4 week washout period with no drinks consumed. Glucose levels were read by a continuous glucose monitor (CGM) during each 2 week period. A 75 g oral glucose-tolerance test (OGTT) was performed at the beginning and end of each intervention period. Blood samples were collected at baseline, and 1 and 2 h for glucose and insulin. A 2 week intake of artificially sweetened beverage (ASB) did not alter concentrations of fasting glucose and fasting insulin, the area under the curve (AUC) for OGTT glucose and insulin, the incremental area under the curve (iAUC) for OGTT glucose and insulin, the homeostatic model assessment for insulin resistance (HOMA-IR), and the Matsuda index compared with the baseline and with the changes after a 2 week intake of mineral water. Continuous 2 week glucose concentrations were not significantly different after a 2 week intake of ASB compared with a 2 week intake of mineral water. This study found no harmful effect of the artificially sweetened soft drink containing acesulfame K (950) and aspartame (951) on glucose control when consumed for 2 weeks by people without Type 2 diabetes.
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Coffee Consumption and Risk of Colorectal Cancer: A Systematic Review and Meta-Analysis of Prospective Studies.
Sartini, M, Bragazzi, NL, Spagnolo, AM, Schinca, E, Ottria, G, Dupont, C, Cristina, ML
Nutrients. 2019;11(3)
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Coffee is the second most widely consumed drink worldwide, after water. It contains many active compounds that affect the health and functioning of the digestive tract. Previous population studies on the relationship between coffee consumption and cancer prevention have had mixed results. The aim of this systematic review and meta-analysis was to provide an up to date summary of the relationship between coffee consumption and the risk of colorectal cancer. The authors looked at 26 prospective studies. When results from the 26 studies were pooled, no significant relationship between coffee consumption and colorectal cancer was found. The researchers then looked at the results by ethnicity and found a protective effect for coffee on colorectal cancer in people from the US. For colon cancer, coffee was protective in men and women combined and in men alone, regardless of ethnicity. When the results were separated according to ethnicity, a significant protective effect was noted in European men and in Asian women. There was no association between coffee consumption and rectal cancer. Decaffeinated coffee demonstrated a protective effect against colorectal cancer in both men and women. The authors concluded that ethnicity could explain the mixed results of previous studies. Further research is needed into the relationship between a person’s genetic make-up and the risk of colorectal cancer associated with coffee.
Abstract
Coffee is a blend of compounds related to gastrointestinal physiology. Given its popularity and the epidemiology of colorectal cancer, the impact of this beverage on public health could be considerable. Our aim was to provide an updated synthesis of the relationship between coffee consumption and the risk of colorectal cancer. We conducted a systematic review and meta-analysis of 26 prospective studies. Regarding colorectal cancer, no significant relationship was detected. Stratifying for ethnicity, a protective effect emerged in US subjects. Concerning colon cancer, coffee proved to exert a protective effect in men and women combined and in men alone. Stratifying for ethnicity, a significant protective effect was noted in European men only and in Asian women only. Concerning rectal cancer, no association was found. Decaffeinated coffee exhibited a protective effect against colorectal cancer in men and women combined. Studies were appraised for their quality by means of the Newcastle-Ottawa Quality Assessment Scale for Cohort studies. Only one study proved to be of low quality. Ethnicity could explain the heterogeneity of the studies. However, little is known about the relationship between the genetic make-up and the risk of colorectal cancer associated with coffee. Further research is warranted.
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Effects of Drugs and Excipients on Hydration Status.
Puga, AM, Lopez-Oliva, S, Trives, C, Partearroyo, T, Varela-Moreiras, G
Nutrients. 2019;11(3)
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A person’s hydration status is determined by water balance, which is inferred as ‘the difference between water input and water output’. Water balance should ideally remain within a tight range allowing for optimal functioning of bodily processes. Many substances as well as those in foods and fluids can affect a person’s hydration status, including several medications and their excipients (an excipient is a substance added to an active ingredient to stabilise the chemicals within the medication, often known as bulking agents or fillers). Fluctuations in hydration status can result from taking certain medications which induce possible side effects, such as diarrhoea/constipation, altered appetite, temperature dysregulation etc. The aim of this review was to analyse previous research carried out investigating the effects of widely prescribed medications and their excipients known to alter hydration status. The authors concluded that several medications and their excipients play a significant role in hydration status and this should be considered by health professionals, especially when prescribing medications to vulnerable patients.
Abstract
Despite being the most essential nutrient, water is commonly forgotten in the fields of pharmacy and nutrition. Hydration status is determined by water balance (the difference between water input and output). Hypohydration or negative water balance is affected by numerous factors, either internal (i.e., a lack of thirst sensation) or external (e.g., polypharmacy or chronic consumption of certain drugs). However, to date, research on the interaction between hydration status and drugs/excipients has been scarce. Drugs may trigger the appearance of hypohydration by means of the increase of water elimination through either diarrhea, urine or sweat; a decrease in thirst sensation or appetite; or the alteration of central thermoregulation. On the other hand, pharmaceutical excipients induce alterations in hydration status by decreasing the gastrointestinal transit time or increasing the gastrointestinal tract rate or intestinal permeability. In the present review, we evaluate studies that focus on the effects of drugs/excipients on hydration status. These studies support the aim of monitoring the hydration status in patients, mainly in those population segments with a higher risk, to avoid complications and associated pathologies, which are key axes in both pharmaceutical care and the field of nutrition.
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Metabolic Syndrome Features: Is There a Modulation Role by Mineral Water Consumption? A Review.
Costa-Vieira, D, Monteiro, R, Martins, MJ
Nutrients. 2019;11(5)
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Metabolic syndrome, defined as having high blood pressure, triglycerides, blood glucose and being obese, is becoming an increasing worldwide health problem. It’s considered to be a result of modern-day life styles and there is no effective cure other than diet and life style interventions. This review paper looks at the mineral content and the alkalising effects of mineral water when consumed by participants with metabolic syndrome. The minerals within mineral water are thought to be more readily absorbed in the body than when consumed in foods and since Westernised diets are low in mineral content and high in acidity, consuming mineral water could help counteract mineral deficiencies and help to balance pH in those with metabolic syndrome. 20 studies, both animal and human, were selected for evaluation of the effect of mineral water on blood pressure, lipid profile, blood glucose and waist circumference. The authors conclude that mineral water is indeed beneficial to those with metabolic syndrome and can help counteract mineral deficiencies and balance pH. However, it is unclear whether mineral water in high quantities would be detrimental to a person with adequate mineral status and a pH within optimal range. Further studies are needed.
Abstract
Metabolic syndrome (MetSyn) promotes, among others, the development of atherosclerotic cardiovascular disease and diabetes. Its prevalence increases with age, highlighting the relevance of promoting precocious MetSyn primary prevention and treatment with easy-to-implement lifestyle interventions. MetSyn features modulation through mineral water consumption was reviewed on Pubmed, Scopus and Google Scholar databases, using the following keywords: metabolic syndrome, hypertension, blood pressure (BP), cholesterol, triglycerides, apolipoprotein, chylomicron, very low-density lipoprotein, low-density lipoprotein, high-density lipoprotein (HDL), glucose, insulin, body weight, body mass index, waist circumference (WC), obesity and mineral(-rich) water. Twenty studies were selected: 12 evaluated BP, 13 assessed total-triglycerides and/or HDL-cholesterol, 10 analysed glucose and/or 3 measured WC. Mineral waters were tested in diverse protocols regarding type and composition of water, amount consumed, diet and type and duration of the study. Human and animal studies were performed in populations with different sizes and characteristics. Distinct sets of five studies showed beneficial effects upon BP, total-triglycerides, HDL-cholesterol and glucose. WC modulation was not reported. Minerals/elements and active ions/molecules present in mineral waters (and their pH) are crucial to counterbalance their inadequate intake and body status as well as metabolic dysfunction and increased diet-induced acid-load observed in MetSyn. Study characteristics and molecular/physiologic mechanisms that could explain the different effects observed are discussed. Further studies are warranted for determining the mechanisms involved in the putative protective action of mineral water consumption against MetSyn features.
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A spatial gradient of bacterial diversity in the human oral cavity shaped by salivary flow.
Proctor, DM, Fukuyama, JA, Loomer, PM, Armitage, GC, Lee, SA, Davis, NM, Ryder, MI, Holmes, SP, Relman, DA
Nature communications. 2018;9(1):681
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Identifying spatial patterns in the human microbiota is necessary to provide insight into mechanisms that either maintain or disrupt its healthy state. The aim of this study was to identify the type and extent of oral spatial patterns formed by bacterial communities, as well as observe the impact of low salivary flow on the spatial patterns. Dental exams were performed on 31 participants to evaluate the oral health status and follow-up was dependent on group allocation. This study found bacterial communities were distinguishable depending on types of teeth and tissue. Further, bacteria on soft and hard tissues varied across the front and back of the oral cavity in a gradient-manner, implying that salivary flow plays a role in establishing the bacterial community gradient in the oral cavity. Based on these results, the authors recommend spatial patterns and processes be explored in other body parts to better understand health and disease.
Abstract
Spatial and temporal patterns in microbial communities provide insights into the forces that shape them, their functions and roles in health and disease. Here, we used spatial and ecological statistics to analyze the role that saliva plays in structuring bacterial communities of the human mouth using >9000 dental and mucosal samples. We show that regardless of tissue type (teeth, alveolar mucosa, keratinized gingiva, or buccal mucosa), surface-associated bacterial communities vary along an ecological gradient from the front to the back of the mouth, and that on exposed tooth surfaces, the gradient is pronounced on lingual compared to buccal surfaces. Furthermore, our data suggest that this gradient is attenuated in individuals with low salivary flow due to Sjögren's syndrome. Taken together, our findings imply that salivary flow influences the spatial organization of microbial communities and that biogeographical patterns may be useful for understanding host physiological processes and for predicting disease.
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Emollient use alters skin barrier and microbes in infants at risk for developing atopic dermatitis.
Glatz, M, Jo, JH, Kennedy, EA, Polley, EC, Segre, JA, Simpson, EL, Kong, HH
PloS one. 2018;13(2):e0192443
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Atopic dermatitis (AD) is a type of eczema common in babies and young children. Poor function of the skin barrier is thought to lead to changes in the composition of bacteria found on the skin. This small study investigated the effects of daily use of an emollient, Cetaphil Moisturising Cream, on the barrier function and bacterial communities on the skin of infants at risk of developing AD. After 6 months, the emollient group had a lower skin pH than the control group. The group using the emollient had more diverse skin bacterial communities than the control group. The proportion of Streptococcus salivarius was higher in the emollient versus control groups. The authors concluded that lower skin pH and increased skin bacterial diversity after long-term emollient use may reduce inflammation and lower the risk of infants developing AD.
Abstract
BACKGROUND Emollients are a mainstay of treatment in atopic dermatitis (AD), a disease distinguished by skin bacterial dysbiosis. However, changes in skin microbiota when emollients are used as a potential AD preventative measure in infants remain incompletely characterized. RESULTS We compared skin barrier parameters, AD development, and bacterial 16S ribosomal RNA gene sequences of cheek, dorsal and volar forearm samples from 6-month-old infants with a family history of atopy randomized to receive emollients (n = 11) or no emollients (controls, n = 12). The emollient group had a lower skin pH than the control group. The number of bacterial taxa in the emollient group was higher than in the control group at all sites. The Streptococcus salivarius proportion was higher in the emollient versus control groups at all sites. S. salivarius proportion appeared higher in infants without AD compared to infants with AD. A decrease in S. salivarius abundance was further identified in a separate larger population of older children demonstrating an inverse correlation between AD severity at sampling sites and S. salivarius proportions. CONCLUSIONS The decreased skin pH and the increased proportion of S. salivarius after long-term emollient use in infants at risk for developing AD may contribute to the preventative effects of emollients in high-risk infants.
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Influence of acute consumption of caffeine vs. placebo over Bia-derived measurements of body composition: a randomized, double-blind, crossover design.
Williamson, CM, Nickerson, BS, Bechke, EE, McLester, CN, Kliszczewicz, BM
Journal of the International Society of Sports Nutrition. 2018;15:7
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Bioelectrical analysis (BIA) is a commonly used method to assess body fat percentage and water values, by running a small electrical current through the body. Prior to testing using BIA, it is necessary to avoid exercise, fasting and caffeine consumption for accurate results. Caffeine’s role as a diuretic is well understood, however, its impact on measures of body water values when consumed prior to BIA testing has not been examined. The main aim of this study was to determine if the consumption of caffeine prior to BIA testing influences the cellular fluid balance and body fat percentage. Participants in the trial were measured on three separate occasions. The first visit worked as a control whilst the second and third visit were conducted using a double blind randomised crossover method. The total number of participants included in the trial were 20 physically active males who were habitual coffee drinkers. Participants were given either 200mg of caffeine or 200mg dextrose (control). The BIA measurements were taken at seven different time points after the preliminary measurements, separated by 15-min. The authors concluded that caffeine consumption in habitual users just prior to testing produced no significant changes in the BIA measurements. Therefore, the pre-testing guidelines for caffeine consumption may not be necessary in habitual caffeine consumers.
Abstract
BACKGROUND Bioelectrical impedance analysis (BIA) is often used to estimate total body water (TBW), intracellular body water (ICW), extracellular body water (ECW), and body fat percentage (BF%). A common restriction for BIA analysis is abstinence from caffeine 12-h prior to testing. However, research has yet to determine whether the consumption of caffeine influences BIA testing results. The purpose of this study was to determine if the consumption of caffeine influences BIA-derived BF% and body water values in habitual caffeine users. METHODS Twenty apparently healthy males (26.6 ± 4.1 years) identified as habitual caffeine consumers (≥ one 95 mg serving per day ≥ four days per week) participated in this study. Participants came to the lab on three occasions, the first visit serving as the control (CON) with no supplementation. The remaining two visits were performed in a randomized double-blind, cross-over fashion. Participants consumed 200 mg of dextrose (PLA) or caffeine (CAF) in capsule form. During each visit, seven multi-frequency BIA measurements were conducted before (PRE) and after (15-min, 30-min, 45-min, 60-min, 75-min, 90-min) consumption. RESULTS Repeated measures ANOVA revealed BF% for CAF was lower than the CON and PLA conditions at PRE and 15-min (p < 0.001, p = 0.004), but not statistically significant for the remaining time points (i.e., 30-, 45-, 60-, 75-, and 90-min). However, the effect size (ES) of the BF% differences were trivial. The CON, PLA, and CAF conditions had higher PRE ICW values than their associated post time points (i.e., 15-, 30-, 45-, 60-, 75-, and 90-min). Similar to BF%, ES of the mean differences for ICW were trivial. No other differences were observed. CONCLUSION Caffeine consumption in habitual users produced trivial changes in TBW, ECW, ICW, or BF%. Therefore, the pre-testing guidelines for caffeine consumption may not be necessary in habitual caffeine consumers.
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Effects of Three Commercially Available Sports Drinks on Substrate Metabolism and Subsequent Endurance Performance in a Postprandial State.
Qin, L, Wang, QR, Fang, ZL, Wang, T, Yu, AQ, Zhou, YJ, Zheng, Y, Yi, MQ
Nutrients. 2017;9(4)
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The depletion of stored glucose and the reduction of the availability of carbohydrates can contribute to fatigue during moderate-to-high intensity exercise. Studies have shown that carbohydrate consumption can reduce the depletion of stored energy and that the combination of protein and carbohydrate supplementation resulted in greater replenishment during intense exercise. Nowadays, most commercial sports beverages contain both carbohydrates and proteins. The present study looked at the postprandial effects of commercially available beverages on carbohydrate and fat metabolism and exercise performance. Ten healthy male participants with a history of running or cycling exercise participated in two studies in a double-blinded, counterbalanced manner. Commercially available beverages with low carbohydrate, high carbohydrate, and a combination of proteins and carbohydrates were tested, and it was found that a beverage containing both proteins and carbohydrates maintained insulin levels and provided greater energy during endurance exercise. It is important to conduct future studies on athletes with higher fitness levels to evaluate the benefits of commercially available beverages. Based on the findings of this study, healthcare professionals can learn more about the benefits of commercially available beverages that combine carbohydrates and proteins and have a low carbohydrate content.
Abstract
Purpose: To examine the effects of commercially available sports beverages with various components on substrate metabolism and subsequent performance. Methods: Two studies were conducted in a double-blinded, counterbalanced manner. Study I was designed to determine the glycemic index, while study II determined the utilization of substrates and subsequent exercise performance. Ten healthy male participants (age 21.70 ± 2.41 years, height 176.60 ± 5.23 cm, weight 66.58 ± 5.38 kg, V̇O2max 48.1 ± 8.4 mL/kg/min) participated in both study I and study II. Three types of commercially available sports beverage powders were used. The powders consisted primarily of oligosaccharides (low molecular weight carbohydrates, L-CHO), hydrolyzed starch (high molecular weight CHO, H-CHO), and whey protein powder with carbohydrate (CHO-PRO). They were dissolved in purified water with identical CHO concentration of 8% (w/v). In study I, each participant underwent two oral glucose tolerance tests (OGTT) and one glycemic response test for each sports drink. In study II, participants cycled for 60 min at 70% V̇O2max, one hour after consuming a standardized breakfast. One of four prescribed beverages (L-CHO, H-CHO, CHO-PRO, and Placebo control, PLA) was served at 0, 15, 30, 45 min during the exercise. Six hours after the first exercise session, participants came back for a "time to exhaustion test" (TTE). Blood samples were drawn at 0, 30, and 60 min in the first exercise session, while arterial blood gas analysis was conducted at 0, 30, and 60 min in both sessions. Subjective feelings (rating of perceived exertion and abdominal discomfort) were also evaluated every 30 min during exercise. Results: Compared to the reference standardized glucose solution, the glycemic index of the L-CHO beverage was 117.70 ± 14.25, while H-CHO was 105.50 ± 12.82, and CHO-PRO was 67.23 ± 5.88. During the exercise test, the insulin level at 30 and 60 min was significantly lower than baseline following the treatment of L-CHO, H-CHO, and PLA (p < 0.05). The CHO oxidation rate at 60 min in the first exercise session was significantly higher than that at 60 min in the second exercise session following the L-CHO treatment (p < 0.05). Time to exhaustion was not significantly different (p > 0.05). Conclusion: The CHO sports beverage with additional PRO maintains insulin production during endurance cycling at 70% V̇O2max in the postprandial state. L-CHO sports beverage suppresses fat utilization during the subsequent exercise performance test. The subsequent exercise performance (as evaluated by TTE) was not influenced by the type of CHO or the addition of PRO in the commercially available sports beverages used in the present study.