Coffee: More health benefits?

5 min read – fact checked ✔

A recently published cross-sectional study (1) investigating the bacterial abundance and compositions of healthy adult gut microbiomes revealed that increased levels of a bacterial species called Erysipelatoclostridium were associated with lower caffeine intakes. The outcomes suggested a potential inverse association between habitual caffeine consumption and Erysipelatoclostridium; a species which previous studies had suggested that increased levels were associated with increased risks of adverse outcomes such as increased obesity, inflammation, and blood glucose dysregulation. The study also observed that both habitual caffeine and coffee intake were associated with an increased bacterial diversity, as well as an increased abundance of Faecalibacterium and Alistipes species, although the associations did not remain statistically significant following adjustment for Vitamin B2 levels. The study sheds light on the potential beneficial associations between increased caffeine intake, coffee consumption and the gut microbiota of individuals with endoscopically normal colons. The association between caffeine, gut microbiota, and health outcomes and the role of Erysipelatoclostridium in metabolic diseases requires further investigation.

Caffeine consumption and the gut microbiome
After water, coffee appears to be the most popular drink worldwide with over 400 billion cups consumed each year (2), often consumed for it’s intense satisfying taste, it’s sociable acceptance, and increased alertness and energy due to caffeine’s competitive inhibition of adenosine A1 and A2 receptors. However, increasing evidence suggests caffeine may offer other long-term health benefits, with studies observing reductions in the risks of developing cardiovascular disease, Alzheimer’s disease, Parkinson’s disease, or even type 2 diabetes (3). Researchers appear to attribute such benefits to the consumption of coffee and it’s ability to modulate the microbiome, and associated with an increased abundance of potentially beneficial bacteria such as the Bifidobacterium species, which evidence suggests may possess anti-inflammatory properties (5). Coffee also contains an array of bioactive compounds, including phenolic (antioxidant) compounds, alkaloids, and diterpenes. There are few studies available investigating the specific phytochemicals within the coffee responsible for the observed effects highlights the need for further research. However, the amount of processing and degree of roasting may considerably affect the coffee bean’s caffeine and antioxidant content which, together with the use (or not) of different milks and the addition of sugar, could differentially influence our gut and explain the conflicting evidence in the literature. Additionally, increasing the roasting process could also influence outcomes. Longer roasting times tends to darken the coffee bean and intensify their flavour, albeit with a reduction of their caffeine and antioxidant content, as well as increased perceived acidity and (potentially) toxic acrylamide levels. Increased roasting may cause coffee’s beneficial Chlorogenic acids to be broken down into the more bitter quinic acid and caffeic acids. Selecting a medium-dark roast may suggest a good balance between coffee’s intense flavour and their beneficlal properties (figure 1).

Figure 1: The effects of roasting coffee beans and their properties (4)

What the study revealed
The researchers conducted a cross-sectional study comparing the mucosal-associated microbiotas of 34 healthy USA-based adults aged between 50 and 75 using 16S rRNA gene sequencing, to establish the effects of both caffeine and coffee intakes. As a result of genetic sequencing of the 97 donated colonic biopsies from the samples obtained, the corresponding frequency consumption was determined from a food frequency questionnaire. The relative abundance of bacterial composition was stratified by comparing low (<82.9 mg) vs. high (≥82.9 mg) caffeine intakes, as well as by ‘never consumed’ or <2 cups vs. 2 cups vs. ≥3 cups of daily coffee intake (figure 2).

Figure 2: Relative abundance of bacterial genera by intake of caffeine and coffee (1)

Whilst the study appeared to establish that both higher caffeine and coffee intakes were associated with a significantly increased bacterial diversity and an increased abundance of Faecalibacterium and Alistipes, their findings did not remain significant [1.49 (0.87–2.56); 2.20 (1.00–4.89)] after adjusting for vitamin B2 using multivariate analysis and their incidence rate ratios. However, a significantly lower abundance of Erysipelatoclostridium did remain significant [0.02 (0.003–0.17)] following such analysis, suggesting an inverse relationship between the species and caffeine intakes which appeared to increase casual inferences and that these associations may not have happened due to chance. Interestingly, daily levels of Vitamins B2, B6 and B12 were higher in cohorts with higher habitual caffeine intakes although it remains uncertain if these associations were due to coffee consumption or whether they were supplementing.

What is the significance of the outcomes?
The study by Dai and colleagues (1) provides insights with regards the relationship that appears to exist between caffeine and coffee, and the microbiota, and that habitual coffee daily could help reduce species associated with increased risks of adverse health outcomes. Higher Erysipelatoclostridium levels have been linked to diet-induced obesity in mouse models and obesity in humans, whilst previous studies showed that patients with type 2 diabetes had higher Erysipelotrichaceae levels than patients with normal glucose tolerance. There is increasing evidence suggesting that the adverse roles of Erysipelotrichaceae and Erysipelatoclostridium in a hosts lipid metabolism, immune responses, inflammation, depression, fatty liver disease, cancer, and their response to cancer immune therapy, The authors suggested that despite the increased diversity and abundance of Faecalibacterium and Alistipes species, the health effects associated to coffee consumption may be partially explained by vitamin B2; apart from a vitamin, also appears to be a prebiotic that is richly present in coffee, although it is possible that other compounds in coffee such as polyphenols, could partly explain their health benefits via alternative mechanisms.

What to do next?
Coffee can be a benign morning ritual for some, but an absolute ‘bomb’ for others, especially post-menopausal women who do not appear to do well with coffee. However, if you are still uncertain whether coffee is good for you, why not arrange a one-to-one consultation with me to learn more about coffee, how to mitigte their effects and consider evidence-based strategies to include it as part of an overall healthy personalised diet. Contact me by email, phone or WhatsApp, or simply use the chat icon on the bottom-left corner of your screen.