The (latest) buzz on caffeine

Caffeine is one of the most commonly consumed substances in the world, found naturally in coffee, tea, cocoa, energy drinks, and various other beverages and added to many processed foods and medications. Its stimulant properties make it a popular choice for boosting energy levels, enhancing alertness, and improving cognitive function. However, alongside its perceived benefits, caffeine has also been the subject of considerable debate regarding its potential positive and negative effects on health. In this article, we investigate the diverse spectrum of health effects associated with caffeine; aiming to present a current overview of both the positive and negative sides of its consumption.

Cognitive function

Caffeine's impact on the central nervous system is widely recognised for its stimulatory effects, often leading to the perception of improved cognitive function. Numerous studies have illustrated caffeine's ability to improve various cognitive parameters, including reaction time, speed, accuracy, learning capabilities, alertness, vigilance, and potentially memory recall (McLellan et al., 2016). Caffeine's cognitive benefits may be particularly pronounced in situations where external factors compromise performance (McLellan et al., 2016). For instance, Antwerpes et al. (2020) observed a positive correlation between regular coffee consumption and cognitive performance among patients experiencing cognitive impairment associated with conditions such as HIV and hepatitis C virus.

Neurological diseases and disorders

Caffeine consumption has consistently been associated with a lower risk of cognitive disorders (Poole et al., 2017). In particular, some research suggests that caffeine consumption may be associated with a reduced risk of Multiple sclerosis (MS), Parkinson's disease (PD), and Alzheimer's disease. Herden et al., (2020) found that coffee intake did not cause severe side effects in MS patients and identified a specific set of patients who might benefit from coffee consumption (Herden et al., 2020). One meta-analysis found that individuals consuming caffeine regularly had a lower risk of developing PD, and those who already had the disease showed a decelerated PD progression (Hong et al., 2020; Jee et al., 20202). Jee et al (2020) also found that caffeine consumption reduces the risk of stroke, dementia, and depression specifically in women.

Physical performance

Caffeine is consumed in many forms when used for the benefit of physical performance such as energy drinks and pre-workout supplements in addition to coffee. It is suggested that caffeine can affect the use of energy in the body during exercise which leads to its positive effects. Caffeine consumption has been shown to enhance physical performance in both athletes and non-athletes (Guest et al., 2021). While aerobic endurance appears to be the form of exercise that benefits both from caffeine, it has also been shown to increase muscular strength and power output; leading to improved athletic performance during both endurance and high-intensity activities (Guest et al., 2021; Wilk et al., 2020; Mielgo-Ayuso et al., 2019). Interestingly, a review conducted by Mielgo-Ayuso et al (2019) found that caffeine’s effects on the male participants (power produced, weight lifted, and sprint performance) were more marked than in the female participants. This indicates that the ability to improve anaerobic performance in men might be higher than in women.

Cancer

Coffee consumption has been found to be protective against several types of cancer including prostate, melanoma, and liver cancers, and to have no association with an increased risk of cancers such as gastric, ovarian, and breast cancer (Poole et al., 2017).

Metabolic effects

Caffeine has been found to have metabolic effects that may aid in weight management and fat loss (See this article for other tips and supplements that can support weight loss: https://www.healthfullymyself.com/post/unlocking-the-power-of-supplements-your-guide-to-weight-loss-support). Studies suggest that caffeine can increase metabolic rate and thermogenesis, leading to greater calorie expenditure and fat oxidation. Coffee consumption is also consistently indicated to lower the risk of type 2 diabetes and metabolic syndrome (Poole et al., 2017)

Mood and depression

Caffeine consumption has been associated with enhanced mood and alertness. Studies have demonstrated that moderate caffeine intake can improve mood, alertness, and vigor, and increase feelings of energy and motivation (Institute of Medicine US Committee on Military Nutrition Research, 1994; McLellan et al., 2016; Lieberman, 2001; Ruxton, 2008). These effects are particularly noticeable when individuals are experiencing factors that typically impair performance, such as sleep deprivation (McLellan et al., 2016). Moreover, a comprehensive review indicated that caffeine, when consumed at normal levels, may have a protective effect on mood and behavior, consistently showing a lower risk of depression (Poole et al., 2017; Lucas et al., 2014; Pham et al., 2014).

Cautions

Caffeine is recognised for its ability to stimulate the central nervous system, potentially resulting in sensations of anxiety, nervousness, and jitteriness among susceptible individuals. Strong evidence suggests that doses within the recommended limit of 400mg/day may cause slight increases in perceptions of anxiety (Wikoff et al., 2017; Rodak et al., 2021). However, it's important to acknowledge that individuals' evaluations of anxiety are subjective and variable; what one person perceives as anxiety may be considered normal by another individual. Moreover, negative responses to lower doses were observed in participants who did not regularly consume caffeine.

Cardiovascular health

Moderate caffeine consumption has been consistently associated with a lower risk of mortality from cardiovascular disease, coronary heart disease, and stroke. Studies indicate that the largest benefits come from drinking three cups of coffee a day (Grosso et al., 2016; Ding et al., 2014). The studies also support caffeine from other sources than coffee. Mineharu et al. (2011) found that green tea consumption up to ≥180 mg (6 or more cups per day) was associated with a decreased risk of total CVD, coronary heart disease, or stroke mortality.

Cautions

While acute ingestion of caffeine can lead to a temporary elevation in blood pressure, habitual consumption tends to result in tolerance. However, the long-term adverse effects of this transient blood pressure elevation on cardiovascular health and risk factors in most individuals remain limited (Wikoff et al., 2017). Moreover, there is variability in the sensitivity of certain individuals to the effects of caffeine on blood pressure. Therefore, for those with primary concerns about blood pressure, it may be advisable to limit caffeine intake to less than the recommended threshold of 400mg/day. Additionally, caffeine consumption has been associated with unfavorable changes in individuals' lipid profiles, particularly LDL cholesterol. However, these changes have predominantly been reported in individuals consuming more than the recommended daily limit of 400mg of caffeine (Poole et al., 2017).

Bone health

It is suggested that excessive caffeine intake may negatively impact bone health by interfering with calcium absorption and increasing the risk of osteoporosis. Overall, the majority of evidence supports that consuming 400mg/day in healthy adults is not harmful concerning bone health and osteoporosis, (Wikoff et al., 2017). However, this cannot be stated confidently. Studies finding reasons for concern regarding bone health and caffeine are not substantial nor consistent and more research into this area is needed. It should also be noted that the studies finding a negative effect of caffeine on bone health were for caffeine consumption within the 200-400mg/day range. If bone health is your primary concern it may be advisable to limit your intake to below this level and ensure that you are consuming adequate calcium to meet your needs (Wikoff et al., 2017).

Reproductive health 

It is suggested that there may be a potential link between high caffeine intake and adverse effects on reproductive health. Caffeine can freely cross the blood–placenta barrier thus exposing the fetus to effects associated with caffeine. In the males and nonpregnant females studied, there were no negative effects on fertility found when consuming 400mg/day (Wikoff et al., 2017). In pregnant women, there appears to be no additional risk of spontaneous abortion, recurrent miscarriage, stillbirth, or birth defects when consuming 300mg or less of caffeine per day (Wikoff et al., 2017).

The overall confidence surrounding these conclusions is not high due to the many confounding factors of pregnancy, poor study designs, and highly varied study results.

Headache and migraine

The exact mechanisms of how caffeine affects headaches and migraines (both negatively and positively) are not fully understood. However, overall, research supports that consumption of ≤400 mg of caffeine is not associated with an increase in headaches. However, headaches induced by caffeine withdrawal are well documented and one analysis reported that 50% of people experience a throbbing, widespread headache during caffeine withdrawal.

When related to migraines, it has been suggested that chronic caffeine overuse may lead to chronic migraines and sudden caffeine cessation may trigger migraine attacks (Nowaczewska et al., 2020). Therefore, it is recommended that those who suffer from migraines should avoid caffeine withdrawal headaches by keeping their daily intake consistent, and it should not exceed 200 mg (Nowaczewska et al., 2020).

Safe and recommended dosages

After examining the evidence, it appears that the following can be used as a guideline:

Healthy adults:          

400mg per day or less which equates to around 4-5 cups of coffee.

One review found that people who consumed three cups of coffee per day had the largest reduced risk of all-cause mortality (a term that refers to death from any cause) compared to non-coffee drinkers (Poole et al., 2017).

Pregnant women:       

300mg per day or less which equates to around 3 cups of coffee.

Migraine sufferers:                

200mg per day or less which equates to 2 cups of coffee.

Exercise performance:

3–6 mg caffeine per kilogram body mass which equates to around 1-2 cups of coffee for most people.

Those concerned about their bone health:

            It is recommended to consult your doctor for personalised recommendations

Those concerned about cardiovascular health:

            It is recommended to consult your doctor for personalised recommendations

Conclusion

Overall, while moderate caffeine consumption is generally considered safe for most healthy adults, it's essential to be mindful of individual tolerance levels and potential negative effects, especially in sensitive populations or those with pre-existing health conditions. Consulting with a healthcare professional can provide personalised guidance on caffeine intake based on individual health status and concerns.

*Disclaimer*

The information presented in this article is for educational purposes only and is based on our interpretation of the current research. Individuals are recommended to consult with a qualified healthcare professionals or registered dietitians for personalised guidance and recommendations tailored to their individual needs and circumstances.

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