Nutrition and mental performance

Attitude towards healthy nutrition and mental toughness: a study of taekwondo athletes

Healthy nutrition is widely considered the cornerstone of optimal athletic performance, both physically and mentally. This study investigates the critical role of healthy nutrition in shaping the physical and mental performance of athletes, with a specific focus on taekwondo. This research aims to explore the potential relationship between taekwondo athletes' attitudes towards healthy nutrition and their mental toughness. The research group comprised 276 active and licensed taekwondo athletes who voluntarily participated in the study (Age M = 17.18 ± SD = 7.13, N = 125 women, N = 151 men). Ethical approval for the research was obtained prior to the commencement of the study. Data collection instruments included the Healthy Nutrition Attitude Scale, Mental Toughness Scale, and a personal information form. Confirmatory factor analysis was conducted to confirm the validity and reliability of the scales. Descriptive statistics, correlation analysis, and regression analysis were performed to explore the relationship between the variables within the research model. The correlation analysis identified two significant, positive, and moderate correlations: (1) between knowledge about nutrition and mental toughness (r = 0.626) and (2) between positive nutrition and mental toughness (r = 0.672). The regression analysis revealed that both knowledge about nutrition (β = 0.360) and positive nutrition (β = 0.461) significantly contribute to mental toughness. The findings suggest that as athletes' knowledge of nutrition expands and their attitudes towards healthy eating become more positive, their mental toughness also appears to improve. These results are both important and original, adding significant new insights to the existing research landscape.

The effect of probiotics on cognitive function across the human lifespan: A systematic review

Recently the scientific community has seen a growing interest in the role of the gut-brain axis and, in particular, how probiotic supplementation may influence neural function and behaviour via manipulation of the gut microbiota. The purpose of this review was to systematically review the current literature exploring the effect of probiotic intervention on cognitive function. PsychINFO, Web of Science, PubMed and Google Scholar were searched for human trials. Studies selected for inclusion administered a probiotic intervention and included at least one behavioural measure of cognitive performance. A total of 30 experimental papers were included, exploring the effect of probiotics across a variety of ages, populations and cognitive domains. The evidence suggests there may be potential for probiotics to enhance cognitive function or attenuate cognitive decline, particularly in clinically relevant adult populations for whom cognitive dysfunction may be present. However, the limited number of studies and the quality of the existing research makes it challenging to interpret the data. Further research is clearly warranted. PROSPERO: CRD42020164820.

Fusing Mobile Phone Sensing and Brain Imaging to Assess Depression in College Students

As smartphone usage has become increasingly prevalent in our society, so have rates of depression, particularly among young adults. Individual differences in smartphone usage patterns have been shown to reflect individual differences in underlying affective processes such as depression (Wang et al., 2018). In the current study, a positive relationship was identified between smartphone screen time (e.g., phone unlock duration) and resting-state functional connectivity (RSFC) between the subgenual cingulate cortex (sgCC), a brain region implicated in depression and antidepressant treatment response, and regions of the ventromedial/orbitofrontal cortex (OFC), such that increased phone usage was related to stronger connectivity between these regions. This cluster was subsequently used to constrain subsequent analyses looking at individual differences in depressive symptoms in the same cohort and observed partial replication in a separate cohort. Similar analyses were subsequently performed on metrics of circadian rhythm consistency showing a negative relationship between connectivity of the sgCC and OFC. The data and analyses presented here provide relatively simplistic preliminary analyses which replicate and provide an initial step in combining functional brain activity and smartphone usage patterns to better understand issues related to mental health. Smartphones are a prevalent part of modern life and the usage of mobile sensing data from smartphones promises to be an important tool for mental health diagnostics and neuroscience research.

The prevalence of iron deficiency anemia in a Saudi University female students

The study aims to determine the prevalence of anemia in apparently healthy university female students. This study was conducted in 2007–2008 at Taibah University and a total of 268 female students participated in this research. In order to assess iron deficiency and iron deficiency anemia, the venous blood samples were collected from consecutive female students at the medical center of Taibah University excluding those already on iron supplementation for iron-deficiency anemia. One hundred and seventy-one (64%) students were found to be anemic. The overall prevalence of mild (10–11 g/dL), moderate (7–10 g/dL), and severe (Hb <7 g/dL) anemia was 45%, 49%, and 6%, respectively. Out of the anemic students, 81% showed microcytic (MCV <80 fL) and 1.6% had macrocytic (MCV >96 fL) variety. The results of this study warrant further evidence-based surveys on a larger scale to validate these findings and eventually set a stage to develop well-organized educational and nutritional programs to safeguard and improve the nation’s health. The high prevalence of iron deficiency anemia in the present study might be related to life style of female students as well as to their dietary habits. It is recommended that female students never skip breakfast as it is essential for their cognitive functions and physical activities.

Mood, food, and obesity

Food is a potent natural reward and food intake is a complex process. Reward and gratification associated with food consumption leads to dopamine (DA) production, which in turn activates reward and pleasure centers in the brain. An individual will repeatedly eat a particular food to experience this positive feeling of gratification. This type of repetitive behavior of food intake leads to the activation of brain reward pathways that eventually overrides other signals of satiety and hunger. Thus, a gratification habit through a favorable food leads to overeating and morbid obesity. Overeating and obesity stems from many biological factors engaging both central and peripheral systems in a bi-directional manner involving mood and emotions. Emotional eating and altered mood can also lead to altered food choice and intake leading to overeating and obesity. Research findings from human and animal studies support a two-way link between three concepts, mood, food, and obesity. The focus of this article is to provide an overview of complex nature of food intake where various biological factors link mood, food intake, and brain signaling that engages both peripheral and central nervous system signaling pathways in a bi-directional manner in obesity.

Development and evaluation of an intervention aiming to reduce fatigue in airline pilots: design of a randomised controlled trial

Background

A considerable percentage of flight crew reports to be fatigued regularly. This is partly caused by irregular and long working hours and the crossing of time zones. It has been shown that persistent fatigue can lead to health problems, impaired performance during work, and a decreased work-private life balance. It is hypothesized that an intervention consisting of tailored advice regarding exposure to daylight, optimising sleep, physical activity, and nutrition will lead to a reduction of fatigue in airline pilots compared to a control group, which receives a minimal intervention with standard available information.

Methods/design

The study population will consist of pilots of a large airline company. All pilots who posses a smartphone or tablet, and who are not on sick leave for more than four weeks at the moment of recruitment, will be eligible for participation.

In a two-armed randomised controlled trial, participants will be allocated to an intervention group that will receive the tailored advice to optimise exposure to daylight, sleep, physical activity and nutrition, and a control group that will receive standard available information. The intervention will be applied using a smartphone application and a website, and will be tailored on flight- and participant-specific characteristics. The primary outcome of the study is perceived fatigue. Secondary outcomes are need for recovery, duration and quality of sleep, dietary and physical activity behaviours, work-private life balance, general health, and sickness absence. A process evaluation will be conducted as well. Outcomes will be measured at baseline and at three and six months after baseline.

Discussion

This paper describes the development of an intervention for airline pilots, consisting of tailored advice (on exposure to daylight and sleep-, physical activity, and nutrition) applied into a smartphone application. Further, the paper describes the design of the randomised controlled trial evaluating the effect of the intervention on fatigue, health and sickness absence. If proven effective, the intervention can be applied as a new and practical tool in fatigue management. Results are expected at the end of 2013.

Trial registration

Netherlands Trial Register: NTR2722

Does the Brain Consume Additional Glucose during Self-Control Tasks?

A currently popular model of self-control posits that the exertion of self-control relies on a resource, which is expended by acts of self-control, resulting in less of this resource being available for subsequent acts of self-control. Recently, glucose has been proposed as the resource in question. For this model to be correct, it must be the case that A) performing a self-control task reduces glucose levels relative to a control task and B) performing a self-control task reduces glucose relative to pre-task levels. Evidence from neurophysiology suggests that (A) is unlikely to be true, and the evidence surrounding (B) is mixed, and is unlikely to be true for subjects who have not recently fasted. From the standpoint of evolved function, glucose might better be thought of as an input to decision making systems rather than as a constraint on performance.

Role of familiarity on effects of caffeine- and glucose-containing soft drinks

Familiarity, through conditioned responses and expectations, may play a significant role in the expression of liking for, and mood and performance effects of, food and drink constituents. The role of familiarity and the effects of caffeine and glucose in Lucozade Energy were investigated by testing this familiar soft drink, and its non-caffeine/non-CHO placebo match, against novel coloured/flavoured full and placebo drinks. Both the familiar drink and its placebo improved alertness, mental energy and mental performance compared to baseline and compared to the novel placebo drink. After repeated exposure, that is, after having gained familiarity with the novel drinks in addition to the already existing familiarity with Lucozade Energy, only the full (caffeine and CHO containing) drinks showed sustained beneficial effects compared to placebo drinks and baseline measures, as well as an increase in liking compared to placebo drinks. Therefore, participants appeared to have learned that beneficial effects were mainly linked to the full products. The results illustrate the restorative combination of caffeine and CHO in the drink, and emphasises the need to implement the appropriate placebo(s) in any study design employing familiar foods or drinks.

Mood and cognitive performance effects of "energy" drink constituents: caffeine, glucose and carbonation

Three studies using healthy volunteers (n = 271) investigated the effects of caffeine, carbohydrates and carbonation in functional "energy" drinks (EDs) with the aim of determining their benefit in every-day life. The results showed caffeine to be the main ED constituent responsible for the effects found, with possible minor, relatively weak effects of carbohydrates. EDs were found to improve and/or maintain mood and performance during fatiguing and cognitively demanding tasks relative to placebo. In terms of absolute values, EDs maintained levels of arousal compared to a deterioration in arousal where placebo was consumed. These effects were found in caffeine-deprived participants, and so may be largely due to "withdrawal reversal". There were only minor differences in the effects of water vs. "sensory-matched" placebo, supporting previous findings indicating that the type of placebo does not alter the conclusions drawn about the effects of the full ED. Finally, carbonation had various effects on mood, some of which were present immediately following consumption, others were consistent with slower absorption of caffeine (and possibly carbohydrates) from carbonated drinks.

Placebo expectancy effects in the relationship between glucose and cognition

The present study investigated the extent of expectancy in the ability of glucose to affect cognitive performance. Using a within-subjects design, subjects (n 26) completed four experimental sessions (in counterbalanced order and after an initial practice session) during which they were given a 500 ml drink 30 min prior to completing a cognitive assessment battery. In addition, all subjects completed a baseline practice session during which they were given no drink. During two of the sessions, subjects were given a drink containing 50 g glucose and on the other two they were given a drink containing aspartame. A balanced placebo design was used, such that for half the sessions subjects were accurately informed as to the content of the drink (glucose or aspartame), whereas in the other two sessions they were misinformed as to the content of the drink. The task battery comprised a 6 min visual analogue of the Bakan vigilance task, an immediate verbal free-recall task, an immediate verbal recognition memory task and a measure of motor speed (two-finger tapping). Blood glucose and self-reported mood were also recorded at several time points during each session. Glucose administration was found to improve recognition memory times, in direct contrast to previous findings in the literature. Glucose administration also improved performance on the Bakan task (relative to the control drink), but only in sessions where subjects were informed that they would receive glucose and not when they were told that they would receive aspartame. There were no effects either of the nature of the drink or expectancy on the other measures. These results are interpreted in terms of there being some contribution of expectancy concerning the positive effects of glucose on cognition in studies which have not used an equi-sweet dose of aspartame as a control drink.

Increased salivary cortisol reliably induced by a protein-rich midday meal

OBJECTIVE

This study was conducted to determine whether an increase in salivary free cortisol would be reliably elicited by a midday meal, thus providing a convenient physiological challenge to the hypothalamic-pituitary-adrenal (HPA) axis, and whether this cortisol release depended on the protein content of the meal.

METHOD

In healthy men, free cortisol was measured in saliva samples taken before and after two identical protein-rich midday meals (39% energy as protein) and compared with a day on which no meal was eaten. Next, in healthy women in a nonclinical setting, salivary cortisol was measured before and after a protein-rich meal (32% energy as protein) on one day and a low-protein meal (5% energy as protein) on another day. Measures of mood, appetite, and psychological well-being were also taken.

RESULTS

An acute meal-dependent increase in salivary cortisol occurred, which was reliable over 2 test days. This increase in cortisol depended on the proportion of protein in the meal, increasing after the high-protein but not the low-protein meal. The extent of this increase in cortisol correlated significantly with poor psychological well-being in women. Some postmeal improvement of mood (positive affect) was associated with the high- but not the low-protein meal.

CONCLUSIONS

The cortisol response to meals may have implications for the effects of meal composition on mood, cognitive function, and food choice. The measurement of free cortisol in saliva provides a psychologically stress-free and reliable technique to assess the cortisol response to a standard protein-rich meal, ie, a physiological challenge to the HPA axis in men and women that could be investigated in naturalistic settings outside the laboratory.

Food, mood and health: a neurobiologic outlook

Hippocrates was the first to suggest the healing power of food; however, it was not until the medieval ages that food was considered a tool to modify temperament and mood, although scientific methods as we know them today were not in use at the time. Modern scientific methods in neuroscience began to emerge much later, leading investigators to examine the role of diet in health, including mental wellbeing, with greater precision. This review shows how short- and long-term forced dietary interventions bring about changes in brain structure, chemistry, and physiology, leading to altered animal behavior. Examples will be presented to show how diets alter brain chemistry, behavior, and the action of neuroactive drugs. Most humans and most animal species examined in a controlled setting exhibit a fairly reproducible pattern of what and how they eat. Recent data suggest that these patterns may be under the neurochemical and hormonal control of the organisms themselves. Other data show that in many instances food may be used unconsciously to regulate mood by seemingly normal subjects as well as those undergoing drug withdrawal or experiencing seasonal affective disorders and obesity-related social withdrawal. We will discuss specific examples that illustrate that manipulation of dietary preference is actually an attempt to correct neurochemical make-up.

The influence of food on pain perception in healthy human volunteers

The aim of this study was to investigate if food could reduce pain perception in a group of 16 healthy human volunteers (8 male and 8 female), and to explore the differential effects of macronutrient composition on the response to cold-induced pain. All subjects underwent the cold pressor test (CPT) on 3 occasions in a counterbalanced order, before and after administration of isoenergetic high-fat low-carbohydrate (CHO) and high-CHO low-fat meals, and when no meal was given. The CPT was carried out 4 times on each test day, once before the meal, and 0.5, 1.5, and 2.5 h after the meal, and at the equivalent times on the day when no food was given. Radial pulse and blood pressure measurements and visual analogue scales of mood/emotional state were carried out before and after each CPT. Mean pain scores were significantly reduced following both meals compared with the no-food condition. The maximum reduction in pain occurred 1.5 h after ingestion, and a significantly greater effect was exerted by the high-fat low-CHO meal compared with the high-CHO low-fat meal. These results demonstrate that food, particularly when rich in fat, significantly reduces the pain induced by the cold pressor stimulus in healthy human subjects.

Overnight caffeine abstinence and negative reinforcement of preference for caffeine-containing drinks

It has been suggested that liking for the taste, flavour and aroma of, for example, coffee and tea is acquired through the process of classical conditioning, involving association of these orosensory cues with the psychopharmacological consequences of caffeine ingestion. Accordingly, this study investigated caffeine reinforcement by assessing changes in preference for a novel drink consumed with or without caffeine. Particular care was taken to use "ecologically valid" procedures; that is, overnight caffeine abstinence followed by a cup-of-coffee equivalent dose of caffeine (70 mg) at breakfast. Caffeine had no significant effects on drink preference or mood in subjects with habitually low intakes of caffeine. In contrast, moderate users of caffeine developed a relative dislike for the drink lacking caffeine and showed somewhat lowered mood following overnight caffeine abstinence (e.g., less lively, clearheaded and cheerful), which was significantly improved by caffeine. These together with other recent results strongly suggest that, in everyday life, caffeine reinforcement can occur as the result of the alleviation by caffeine of the adverse effects of overnight caffeine abstinence (negative reinforcement). They also demonstrate the utility of this flavour-conditioning procedure, which could be applied in the wider investigation of the reinforcing properties of drugs.