Focused Eating - Part 2

Part 2: A Hug from a Mug

By James Collier; Registered Nutritionist; Huel Co-Founder and Head of Sustainable Nutrition

Continues from Part 1.

When we’re tired, not only do we feel like we’re low on energy, but our ability to pay attention can be challenging, too. In Part 1, we looked at the effects of sugar on our cognitive ability, whether intermittent fasting is a useful strategy and how omega-3 fats can influence our ability to concentrate. But maybe all that’s required is the feel-good factor of a hot drink when we need perking up.

Cognitive Caffeine

Coffee is one of the most consumed beverages in the world with around two billion cups being imbibed every day – that’s about 83 million per hour [17]. This dark, rich liquid began its global expansion from the highlands of Ethiopia where the stimulating effects of caffeine were first observed. Today, espresso cups populate cities across the world and most people will admit to not function without downing first their double-shot mochaccino.

So why is coffee so popular and what’s driving this insatiable thirst? Its widespread popularity owes a lot to the recognition that coffee is more than a caffeine kick. The main biologically active ingredients are caffeine (also found in tea, chocolate and certain other plants) and a suite of antioxidants. Upon ingestion, caffeine is absorbed, metabolised and quickly shuttled to the brain, where it works as a stimulant, at least in part, by blocking adenosine – a chemical that promotes sleep – from binding to its receptor [18]. Caffeine is a psychoactive compound: it changes our mental state by acting on the central nervous system. At low doses (1-3 cups per day), coffee sharpens people’s minds making it possible for sleep-deprived, underprepared students to pull an all-nighter to meet their impending deadlines. A 2021 pan-European survey of over 5,000 individuals, found that consuming 75mg of caffeine – the equivalent of one cup of coffee – every four hours led to substantial mood improvement over the course of the day [19]. This finding fits well with at least one previous study, conducted at the Harvard School of Public Health, that indicated that caffeine might even work as a mild antidepressant, lowering the risk of depression by as much as 20% in women [20]. But there’s a catch. Overuse (over 500-600mg a day) can lead to “caffeine intoxication”: unpleasant side effects that include wrecked sleep, shakiness, irritability and gastric distress. Excessive reliance on caffeine can further turn dependency into a hard-to-shake habit, leading to a full-blown substance use condition that’s been named “caffeine-use disorder”, listed in the DSM-5, and can lead to pervasive mental health consequences [21]. Caffeine, it seems, doesn’t just keep you alert but has the power to turn you into a walking ray of sunshine, provided you don’t overdo it.

Warm and Happy

This leads us to another important aspect of coffee and, indeed, other beverages: temperature. For most people, temperature is the reason why tea and coffee become a morning ritual: the indulging heat of our morning cup helps fight off the foggy haziness that accompanies us out of bed. In fact, hot beverages can also work the other way: if you’re feeling tired or under the weather, it’s comforting to climb into bed with a hot mug in your hands. The temperature of our drink can have a direct effect on our mood and cognition. But the question is, does it? The neuroscience of thermal sensation is fraught with examples of how rises in temperature evoke positive emotional responses in humans. In a 2017 study, participants were asked to rate either coffee or green tea served at cold (5°C), ambient (25°C), and hot (65°C) temperatures. Not surprisingly, beverages consumed at 65°C were more likely to trigger “emotions of positive valence, such as ‘pleased’, ‘happy’, ‘warm’ than those consumed at either 25 or 5°C” [22]. Not only do hot drinks make people happy but they can also sway our decision making. Research shows that humans rate strangers as 11% “warmer” when holding a hot drink in their hands compared to holding a cold drink [23]. Although some psychologists feel the claim is contentious, the warmth of a drink might determine how friendly you are towards someone you’ve just met. While useful, this falls short of explaining other behaviours linked to hot drinks. Why do we offer a hot cuppa to an upset friend? In Britain, the gesture of offering tea is presumably rooted in tradition: sharing a cup of tea is an act of compassion and offers an effective social support strategy. In the face of its cultural pervasiveness, it might perhaps then come as a surprise that scientists are only just beginning to untangle the benefits of drinking tea on mood and cognition. In 2014, for example, researchers reported that in a healthy Japanese population, those who drank four or more cups of green tea per day were 51% less likely to develop depression over their lifetime than those who drank less or no tea [24]. But, as we have learned, epidemiological studies have limitations and other factors may be responsible for the positive results (i.e. diet, socioeconomic status or simply genetics).

The take-home message? If you drink coffee in moderation, savour those sips, harness the surge in energy and enjoy the benefits. Too much caffeine, however – especially too late in the day – inhibits sleep, and having too little sleep, of course, will more than cancel out any caffeine-derived cognitive benefits. We don’t yet know how coffee can alleviate symptoms of depression, but it may be to do with its special combination of antioxidants that are thought to dampen pathological changes in the brain of depressed individuals [25]. For instance, polyphenols with anti-inflammatory potential may protect against low-grade inflammation in depression. Another hypothesis is that caffeine facilitates the release of feel-happy chemicals in the brain such as serotonin and dopamine [26]. It’s suggested that caffeine stirs up the amount of dopamine that binds to dopamine receptors in the forebrain – a key area of the brain involved in motivation, decision making and reward. When it comes to the science of hot drinks, we may need to wait a few years before fully appreciating their effects on our wellbeing. Remarkably little is known about how tea can help us to escape the clutches of depression. Although there’s convincing evidence of improvements to mood in healthy populations, researchers are still trying to identify the active compounds that give tea its mental health benefits. Despite there being little evidence – at least for now – showing that tea can help improve our mood, in a world oppressed by ever-increasing rates of mental health struggles, may have far-reaching consequences. Besides, who doesn’t like a good old cuppa?

References:

17. https://britishcoffeeassociation.org/coffee-consumption/ [accessed 19/04/2022]

18. Ribeiro JA & Sebasti?o AM. “Caffeine and adenosine.” J Alzheimers Dis. 2010; 20(1):S3-15.

19. https://www.coffeeandhealth.org/2021/10/drinking-coffee-helps-to-improve-mood-as-days-get-shorter/ [accessed 19/04/2022]

20. Lucas M, et al. “Coffee, Caffeine, and Risk of Depression Among Women.” Arch Intern Med. 2011; 171(17):1571-8.

21. Addicott MA. “Caffeine Use Disorder: A Review of the Evidence and Future Implications.” Curr Addict Rep. 2014; 1(3):186-92.

22. Pramudya RC & Seo HS. “Influences of Product Temperature on Emotional Responses to, and Sensory Attributes of, Coffee and Green Tea Beverages.” Front Psychol. 2018; 8:2264.

23. Williams LE & Bargh JA. “Experiencing physical warmth promotes interpersonal warmth.” Science. 2008; 322(5901):606-7.

24. Pham NM, et al. “Green tea and coffee consumption is inversely associated with depressive symptoms in a Japanese working population.” Public Health Nutr. 2014; 17(3):625-33.

25. Wang L, et al. “Coffee and caffeine consumption and depression: A meta-analysis of observational studies.” Aus & NZ J of Psych. 2016; 50(3):228-42.??

26. Ferré S. “An update on the mechanisms of the psychostimulant effects of caffeine.” J Neurochem. 2007. 105(4):1067-79.