Supplements for your brain, an ambiguous topic. Sports supplements are fairly common now although still confusing. This post will give you a greater understanding of which are scientifically proven to help cognitive function when put under stress.

The latest research from the International Journal of Sport Nutrition and Exercise Metabolism titled “Nutritional Supplements and the Brain” by Romain Meeusen and Lieselot Decroix from the Human Physiology Research Group – Vrije Universiteit Brussels, Belgium, has some excellent findings. In this paper, they have looked at several supplements that are said to be good for your brain and found the facts.

Supplements for your brain

Cognitive function plays an important role in athletic performance and it seems that brain functioning can be influenced by nutrition and dietary components. Thus, the central nervous system might be manipulated through changes in diet or supplementation with specific nutrients including branched-chain amino acids, tyrosine, carbohydrates and caffeine.

Food and your brain

Thinking about food can modulate neural activity (a brainwave) in specific brain areas known to be involved in the cognitive controls of appetitive behaviours. This leads to saliva production, gastric acid and insulin secretion.

When food is eaten, smell and taste act as additional stimuli to recall memorial representations of experiences with particular food items. These memorial representations can be pleasant or unpleasant (e.g. conditioned food/taste aversion). It is clear that nutrition and supplements will influence brain functioning. Nutrition provides the proper building blocks for the brain to create and maintain connections, which is critical for improved cognition and academic or even athletic performance.

Food and its functionality

Dietary factors have a broad and positive action on neuronal function and plasticity. For example, the omega-3 fatty acids, that are typically found in high concentrations in algae and fish, provide building material to the brain. Diets rich in sugar, saturated fats or high in calories are considered harmful for neural function, as they act to elevate levels of oxidative stress and reduce synaptic plasticity and cognitive functions.

Brain function is dependent on adequate nutrition. There is increasing interest in examining the possible influence of supplements on exercise performance, especially endurance performance. However, it is clear that performance in many sports also involves high-intensity exercise which includes immediate decision making and skill accuracy. Sports performance depends on the interaction of the brain with the periphery. Motor control, decision making, coordination, reaction time and other cognitive tasks can be essential during several sports. Fatigue does not only occur at the peripheral level, ‘central’ fatigue or ‘mental’ fatigue exist involving brain mechanisms. Cognitive function plays an important role in athletic performance and research suggests that brain functioning can be influenced by nutrition.

Cognitive performance in sports

In most sports players need to react dynamically. This requires strong visual attention, executive function and athletes often rely on working memory for decision making.

Cognitive flexibility and inhibitory control are necessary for passing and decisions on how to dribble, etc. The literature on the influence of fatigue on cognitive performance shows that both mental fatigue and physical fatigue can impair performance on a cognitive task or a sport-specific performance.

Dehydration

The effect of hydration status on the performance of various exercise tasks has been studied extensively. These studies have found that hydration status can affect the brain.

Dehydration and hyperthermia result in the transient opening of the blood-brain barrier. This may have implications for the stability of the cerebral environment during exercise. Studies have found that when dehydrated, subjects exerted a higher level of neuronal activity in order to achieve the same performance level as when hydrated. Evidence suggests that dehydration can impair cognitive performance and mood even without hyperthermia. This induces a negative influence on vigilance and working memory and can increase tension, anxiety and fatigue.

Sports where ‘quick decision making’ is required are thought to be the most affected as it can affect thinking time. Take football (soccer) players for example, when they have little time to think about what pass to play or if they should shoot at the elite level there is very little thinking time. Or perhaps as a Quarterback in the NFL. New England Patriots Quarterback Tom Brady apparently drinks up to 2 gallons of water a day. Yes, this is probably too much but maybe this helps him make his quick decisions?

Creatine

It is well known that supplementation of creatine monohydrate will increase muscle creatine, resulting in improved performance in short duration, intensive exercise, such as weightlifting. This muscle building supplement will also buffer energy supplies to the brain since it is an organ with high energy demands. Emerging evidence suggests that creatine has a positive effect on brain functions (including cognition) in circumstances where brain energy supply is suboptimal. However, the evidence for a positive effect of creatine on brain function in healthy individuals is only moderate.

Nutritional Supplements and Fatigue

Events arising entirely from within the brain can influence an individual’s sensation of fatigue and thus potentially affect performance. This opens an opportunity to manipulate the central nervous system through changes in diet or supplementation with specific nutrients, including amino acids such as branched-chain amino acids (BCAAs), tyrosine, carbohydrates (CHO) and caffeine. The original central fatigue hypothesis (Newsholme et al., 1987) suggested that changes in the mobilisation of substrates (CHO, fat) that occurs during exercise produces a direct effect on the production of the neurotransmitter, serotonin (5-HT) within the brain. During exercise, the entry of tryptophan – precursor of 5-HT – into the central nervous system through the blood-brain-barrier is favoured by increased muscle BCAA’s and elevated plasma fatty acids as this elevates the ratio of unbound tryptophan to BCAA. This increases the amount of tryptophan crossing the blood-brain-barrier, consequently leading to higher 5-HT concentrations in the brain (Meeusen, 2014; Roelands & Meeusen, 2010). Serotonin has been linked to fatigue because of its well-known effects on sleep, lethargy and loss of motivation. An exercise-induced increase in extracellular serotonin concentrations in several brain regions was suggested to contribute to the development of fatigue during prolonged exercise.

Branched Chain Amino Acids and Central Fatigue

Central fatigue is associated with changes in the synaptic concentration of neurotransmitters within the central nervous system (CNS; including the brain and spinal cord) which affects exercise performance and muscle function.

The ingestion of BCAAs causes a rapid elevation of their plasma concentrations and increases their uptake into the brain. Supplementation of BCAAs has been proposed as a possible strategy to limit the development of central fatigue. Although this is a very attractive theory, there is limited or only circumstantial evidence to suggest that exercise performance in humans can be altered by nutritional manipulation with BCAA supplements.

While there is some evidence of BCAA ingestion influencing ratings of perceived exertion (RPE) and mental performance, the results of several well-controlled laboratory studies by Van Hall et al failed to demonstrate a clear positive effect on exercise capacity or performance during prolonged fixed intensity exercise to exhaustion.

Tyrosine and Central Fatigue

Tyrosine is a supplement that many of you may be less familiar with. It’s an amino acid which is used to synthesize protein. It is commonly found in high protein foods such as chicken, turkey, fish, milk, cottage cheese, nuts and seeds.

This amino acid has been linked to improving memory and increasing plasma neurotransmitter levels (particularly dopamine and norepinephrine). It is also linked to stress reduction in hot and cold conditions.

During a military setting, tyrosine was shown to prevent declines in various aspects of cognitive performance and mood associated with stress encountered.

Tyrosine and heat stress

Interestingly, research by Lieberman (2003) found that there is some evidence that vigilance, choice reaction time, pattern recognition, coding and complex behaviours (such as map-compass reading), are improved by tyrosine administration when volunteers are exposed to the combination of cold and high altitude (Lieberman, 2003).

Exercise in the heat represents a specific demand on brain dopamine (DA) which is not apparent in more pleasant conditions. Therefore, the brain tyrosine requirement may be greater with the cumulative demands of exercise and heat stress and may become a limiting factor for DA synthesis and release. Tumilty et al. (2011) assessed the effects of acute tyrosine supplementation on exercise capacity in the heat and showed that supplementing a nutritional DA precursor one hour before exercise was associated with increased exercise capacity. This demonstrated that tyrosine availability, at least in part, may influence prolonged exercise tolerance with heat stress.

Carbohydrates and Central Fatigue

Another nutritional strategy that may influence the development of central fatigue is carbohydrate feeding. The beneficial effect of carbohydrate supplementation during prolonged exercise could also relate to increased (or maintained) substrate delivery for the brain, with a number of studies indicating that hypoglycemia affects brain function and cognitive performance.

Glucose and the brain

The brain consumes ca. 130g of glucose daily. Therefore thus in a resting state, a large portion of the available glucose will be used by the brain. Glucose is stored in the brain as glycogen and can be degraded in response to sudden increases in energy demand such as periods of increased neuronal activity during cognitive processes and prolonged endurance exercise. Along with glycogen, glucose is the primary fuel source of the brain, but lactate (lactic acid) can also contribute to fueling the brain.

Glucose appears to have a greater effect on cognition when task difficulty is increased or when attention is divided between two tasks. There is also evidence that impaired glucose regulation is associated with impaired cognition, particularly episodic memory. This impairment is minimal in young people but increases in older people where it may compound other ageing processes leading to reduced brain function.

Supplement studies

Several mouth-rinse studies (by Chambers et al., 2009, Sanders et al., 2012, Carter et al. 2004, Pottier et al., 2010 and Rollo et al., 2008, 2010, 2011) have found that the presence of a glucose solution in the mouth can result in improved physical and cognitive performance.

Recently, a glucose nasal spray clearly showed the direct connection between the nasal mucosa and several brain areas. Glucose nasal spray substantially increased the average power output during a time trial. In line with mouth rinsing, glucose showed to substantially enhance endurance performance. This is probably due to the activation of the olfactory pathway and/or extraoral sweet taste receptors. Greater cognitive efficiency was observed with glucose nasal spray.

Other brain fuels

Ketone bodies such as acetoacetate and β-hydroxybutyrate (βHB) are synthesized in the liver from fatty acids when carbohydrate levels are low. Ketones act as a backup fuel for the brain when energy levels are low, such as during periods of starvation. The theory is that dietary supplementation with medium-chain triacylglycerides (TAG) can improve cognitive function by providing the brain with energy in the form of ketones. However, only a few human studies have examined the influence of nutritional ketosis, therefore there is no conclusive evidence yet. It has been reported that some “ultra-endurance athletes frequently find mental clarity is maintained better during prolonged exercise in the keto-adapted state”. However, this cannot be sufficient to provide evidence for the use of ketones or a keto-adapted diet as possible nutritional interventions to influence the mental performance of athletes.

Caffeine and Central Fatigue

Caffeine has long been recognised as an ergogenic aid. For a while, caffeine use was restricted for athletes and it was only removed from the list of controlled substances in January 2004, when it was put on the monitoring list.

We have recently posted a few stories about the benefits of caffeine, such as Does caffeine improve your workout? Your genes may decide.

The stimulatory effect of caffeine is believed to stem from its ability to antagonise the actions of adenosine. Caffeine easily crosses the blood-brain barrier due to its lipophilic properties and has been shown to counteract most of the inhibitory effects of adenosine on neuro-excitability neurotransmitter release and arousal. Since caffeine is known to antagonise adenosine receptors in the brain, and adenosine inhibits the release of DA, logically, caffeine will induce higher brain DA concentrations. Low to moderate (0.5 mg.kg-1 – 4 mg.kg-1) caffeine doses improve alertness, vigilance, attention and reaction time, but less consistent effects are observed on memory and higher-order executive function, such as judgment and decision making. Caffeine is well known to enhance performance and reduce the perception of effort during prolonged exercise and will also influence specific reward centres of the brain.

Supplements, plant products and herbal extracts

There are many new supplements coming onto the market with various claims. Some claim to make you stronger, others claim to make you fitter and some claim to improve cognitive function. Let’s take a look at some of the latest scientific research.

Omega-3 fatty acids

Omega-3 fatty acids are essential for supporting intercellular signalling events and therefore positively influence synaptic function. Many clinical and animal studies demonstrate the importance of long-chain polyunsaturated fatty acids (LCPUFA) in neural development and neurodegeneration. Omega-3 fatty acids such as docosahexaenoic acid (DHA) are involved in multiple brain functions including cell membrane fluidity, receptor affinity, modulation of signal transduction molecules and cognitive function. Recently these fatty acid are suggested to act as recovery aids, or possibly a prophylactic nutritional measure for concussion or mild traumatic brain injury. More studies need to be done but one day they could be used against sports-related concussion.

Plant products

Naturally occurring plant products and herbal extracts such as polyphenols, ginseng, ginkgo biloba, etc. have grown in popularity as possible agents to improve performance or recovery from exercise. These dietary constituents are marketed as supplements to enhance (sports) performance. Biological supplements typically contain chemical compounds extracted from fruits, vegetables, roots, etc. Some of these supplements seem to have an influence on the central nervous system, including the brain. Others will
not influence the brain. Many are thought to enhance cognitive function and postpone (central) fatigue, but there is little evidence that they influence sports performance.

Polyphenols

There has recently been growing interest, supported by a number of epidemiological and experimental studies, on the possible beneficial effects of polyphenols on brain health. Polyphenols are abundant micronutrients in plant-derived foods and are powerful antioxidants. Fruits and beverages such as tea, red wine, cocoa and coffee are major dietary sources of polyphenols. The largest group of polyphenols is the flavonoids. A recent first meta-analysis of polyphenols and their effect on human athletic performance suggested that polyphenol supplementation (and especially quercetin) is associated with a clear moderate improvement of performance with no reported adverse effects. Polyphenols have consistently been associated with a reduced risk of developing dementia, improved cognitive performance in normal ageing and improved cognitive evolution. The neuroprotective actions of dietary polyphenols involve a number of effects within the brain. Including a potential to protect neurons against injury induced by neurotoxins, an ability to suppress neuroinflammation and the potential to promote memory, learning and cognitive function.

 

Cocoa flavanols

Our old friend chocolate. We have done several posts on this in the past, such as The surprising benefits of chocolate and Dark chocolate could help boost athletic performance.

Cocoa flavanols as found in dark chocolate have been reported to have beneficial effects on cognition but it is not known if this effect is also present in combination with exercise. Acute cocoa flavanols intake increased cerebral oxygenation during a cognitive task assessing executive function, but without any impact on cognitive performance. Studies from Decroix et al., (2016) found when combining cocoa flavanols and exercise, cocoa flavanols had no additive effect on the exercise-induced cognitive enhancement and the associated increased cerebral oxygenation and perfusion.

Beetroot juice

You may have seen our recent webinar Rocket (and Beetroot) Science: Dietary Nitrate and Exercise Performance by the excellent Professor Andrew Jones. This webinar discusses the benefits of nitrate, in particular, beetroot juice has on cardio performance.

Dietary nitrate has been shown to improve endothelial function, reduce blood pressure and the oxygen cost of submaximal exercise and increase regional perfusion in the brain. The results of 2 recent studies show that single doses of dietary nitrate enhances repeated sprint performance and may attenuate the decline in cognitive function (and specifically reaction time) that may occur during prolonged intermittent exercise. It modulates the cerebral blood flow response to task performance and potentially improves cognitive performance.

Other plant products

The consumption of tea, polyphenol-rich foods, fruit and vegetable, and total amounts of flavonoids have been shown to be associated with protection against or slowed progression of, cerebrovascular diseases, such as strokes and neurologic disorders, including dementia, and cognitive impairment/decline in elderly populations. There is very little research on young adults and hardly anything on athletes.

Ginseng

Ginseng is commonly used by individuals who are fatigued and under stress, but most studies on cognitive aspects (alertness, fatigue, mood, motivation) show mixed results. Dalinger (1966) found that ginseng improved ratings of fatigue and motor skills in athletes taking part in a Biathlon.

Ginkgo biloba

This herbal extract is used widely in traditional Chinese medicine. Ginkgo biloba is believed to improve memory and other aspects of cognitive function. The results on the acute effects of Ginkgo biloba intake are conflicting.

Guarana

Guarana seed comes from plants found in the Amazon. It contains theophylline, theobromine and caffeine. Theobromine is a methylxantine that is an adenosine receptor antagonist (as caffeine) and might improve cognitive function. Two studies have investigated the effects of guarana on cognitive performance and found that memory, mood and speed during an attention task improved. The administration of a vitamin and mineral complex with guarana has been shown to attenuate mental fatigue and improve performance during cognitively demanding tasks. Veasey et al. (2015) showed that consuming a vitamin and mineral complex containing guarana, prior to exercise, can positively impact subsequent memory performance and reduce perceived exertion during a moderate-intensity run in active males. Probably the caffeine content and/or the combination with theobromine could be responsible for these effects. Pomportes et al. (2017) recently investigated the influence of serial mouth rinsing with guarana complex on cognitive performance (i.e., cognitive control and time perception) during a 40-min submaximal exercise, and found a ‘likely’ improvement on a cognitive task. However, when examined more carefully this commercial product also contains caffeine which could be the reason for the positive results.

Rhodiola Rosea

There have been some positive results regarding supplementation of the plant Rhodiola Rosea. It might improve cognitive performance and reaction time. Rhodiola Rosea is reported to influence endurance performance too. The plant decreases heart rate response to submaximal exercise and appears to improve endurance exercise performance by decreasing the perception of effort. It may also improve mood and cognitive function.

Sage

Sage improves alertness (Kennedy et al., 2006) and memory (Tildesley et al., 2003, 2005). No studies with sage have yet been performed in athletes.

Conclusion

This conclusion comes from the authors of the study. The brain uses a large amount of energy and it seems that it is not that easy to disturb brain homeostasis. Several nutrients and supplements will influence brain functioning, but not many of these nutritional constituents have been the subject of well-controlled studies in exercise science. Carbohydrate and caffeine have an influence on several aspects of cognitive function and they can also influence exercise performance. For most of the herbal products, there is only “anecdotal” evidence that they can influence brain functions. However, more studies are necessary to determine the exact dosage of supplementation and also which cognitive domains are influenced the most when these supplements are taken. Most of the other supplements that have evidence to influence brain function in specific populations such as individuals with cognitive decline, dementia or Alzheimer’s disease lack evidence in sports science. There is a need for well-controlled randomised studies with well-defined outcome measures before the ‘claims’ on beneficial effects of supplements on brain functioning can be established.

Want more? Read the full journal article here published in the  International Journal of Sport Nutrition and Exercise Metabolism.

For more on cognitive function and attention for sports performance check out Attention and performance – The impact on motor control and learning.