Key Findings and Implications of a Recent Systematic Review of the Potential Adverse Effects of Caffeine Consumption in Healthy Adults, Pregnant Women, Adolescents, and Children

Abstract

In 2016–2017, we conducted and published a systematic review on caffeine safety that set out to determine whether conclusions that were presented in the heavily cited Health Canada assessment, remain supported by more recent data. To that end, we reviewed data from 380 studies published between June 2001 and June 2015, which were identified from an initial batch of over 5000 articles through a stringent search and evaluation process. In the current paper, we use plain language to summarize our process and findings, with the intent of sharing additional context for broader reach to the general public. We addressed whether caffeine doses previously determined not to be associated with adverse effects by Health Canada (400 mg/day for healthy adults, 300 mg/day for pregnant women, 2.5 mg/kg body weight/day for adolescents and children, and 10 g/day for acute effects) remain appropriate for five outcome areas (acute toxicity, cardiovascular toxicity, bone & calcium effects, behavior, and development and reproduction) in healthy adults, pregnant women, adolescents, and children. We used a weight-of-evidence approach to draw conclusions for each of the five outcomes, as well as more specific endpoints within those outcomes, which considered study quality, consistency, level of adversity, and magnitude of response. In general, updated evidence confirms the levels of intake that were put forth by Health Canada in 2003 as not being associated with any adverse health effects, and our results support a shift in caffeine research from healthy to sensitive populations.

Maternal caffeine consumption and pregnancy outcomes: a narrative review with implications for advice to mothers and mothers-to-be

“…9 Through its Caffeine Working Group and affiliated industry organisations, including the American Beverage Association and the National Coffee Association, ILSI has supported the production of a body of published articles depicting caffeine as a benign substance posing little or no threat to fetal health and development. [114][115][116][117][118][119][120][121] Scientific evidence to the contrary has been portrayed in that literature as methodologically flawed due to confounding from uncontrolled variables.…”

“…Spurious conclusions have been a recurring feature of industry-affiliated commentary. [114][115][116][117][118][119][120][121] For example, one review concluded that the "evidence does not support a positive relationship between caffeine consumption and adverse reproductive or perinatal outcomes" (p. 2573, emphasis added), 117 while another concluded that daily consumption of caffeine is "not associated with adverse reproductive and developmental effects" (p. 637, emphasis added). 119 Yet, in reality, even industry-affiliated commentaries agree with independent opinion that maternal caffeine consumption is associated with (ie, has a 'positive relationship' with) negative pregnancy outcomes.…”

“…119 Yet, in reality, even industry-affiliated commentaries agree with independent opinion that maternal caffeine consumption is associated with (ie, has a 'positive relationship' with) negative pregnancy outcomes. Notwithstanding universal agreement that relevant associations have been established as undeniable fact, ILSI-affiliated literature [114][115][116][117][118][119][120][121] has promulgated an opportunistic deception by conflating association and causation, wherein legitimate questions about causation have been used to make false claims 117 119 about absence of evidence of association.…”

Caffeine and Pressure Flow Autoregulation

“…It has various benefits such as respiratory stimulation in premature infants with sleep apnea [1] [2]. World Journal of Cardiovascular Diseases However, it is most frequently consumed in beverages or as over-the-counter capsules, pills and tablets to boost one's energy [3]- [8]. Thus, abuse of caffeine has become a habit for many people even though there are unanswered questions about its effects on the body, especially the brain and cardiovascular system.…”

Caffeine and Reactive Hyperemia

“…some clinical benefits such as respiratory stimulation in premature infants suffering from sleep apnea [1] [2]. However, it is most commonly consumed in beverages and as over-the-counter capsules, pills and tablets because consumers believe it boosts their energy, enhances motivation, improves gym performance, and/or reduces disease [3]- [8]. Thus, abuse of bodies and minds by caffeine has become a pastime for many consumers even though there are unanswered questions about its aphysiological effects on the body, especially the brain and cardiovascular system.…”