Coffee is more popular than ever, according to a March 2020 survey conducted by the National Coffee Association. Seven in 10 Americans drink coffee every week, 62% drink it every day, and the average American coffee drinker consumes a bit more than 3 cups a day.
Americans sure love their joe. And, java may love its drinkers back. Recent research indicates that regular coffee consumption could ease depression. Here’s a look at the evidence.
Evidence of benefit
In a review published by Alan Leviton, a professor of Neurology at Harvard Medical School, the following two studies quantify the mood benefits of coffee:
In meta-analyses including more than 300,000 participants—with 8,000 exhibiting depression—researchers discovered that people who drank more coffee were at a decreased risk for depression compared with those who drank less or no coffee. The peak benefit occurred in those who drank about 400 mL per day, or 13 ounces.
In a Korean study involving nearly 10,000 adults, also included in the review, researchers found that those drinking more than 2 cups a day exhibited a 32% lower prevalence of self-reported depression compared with those who did not drink coffee.
Results from a study published in Nutrients further support the antidepressant effects of coffee. In the study, Spanish researchers examined the relationship between coffee intake and the risk of depression in 14,413 university graduates, while controlling for adherence to the Mediterranean diet. Researchers used a food-frequency questionnaire to assess coffee intake.
The investigators found that those who drank at least 4 cups of joe a day were at significantly lower risk of depression compared with those who drank fewer than 1 cup a day. Of note, researchers observed no overall inverse linear dose-response association between coffee consumption and depression incidence.
The researchers noted that previous studies supported their findings involving extremes in coffee consumption. Furthermore, they found that decaffeinated coffee did not decrease the risk of depression.
In the aforementioned Spanish study, researchers suggested two possible reasons why coffee could curb rates of depression.
“First, coffee is the main dietary source of caffeine. Caffeine is an alkaloid exerting a stimulant effect on the central nervous system and modulating the dopaminergic activity by nonspecific antagonism against A1/A2 adenosine receptors. A moderate amount of caffeine has a beneficial effect, improving psychomotor activity, vigilance level, and increasing the perception of feeling more energetic,” the authors wrote.
“Second, coffee has a high concentration of polyphenols, such as chlorogenic acid and trigonelline, which have anti-inflammatory potential. Thus, coffee consumption could protect against low-grade inflammation, which seems to be involved in the pathogenesis of depression. In fact, coffee is the main dietary source of polyphenols in some populations such as the US or Northern Europe, where the other prospective studies on coffee and depression had been conducted,” they added.
In his review, the Harvard researcher Alan Leviton mentions other possible mechanisms. First, polyphenol flavonoids found in brewed coffee are a rich source of antioxidants, and antioxidant intake has been linked to lower levels of depression in women.
Leviton also explained that components of brewed coffee could influence the gut microbiome, fighting depression.
“Psychobiotics offer the promise of diminishing depressive symptoms, thereby justifying the claim that probiotics and prebiotics are capable of modulating depression and depressive mood. Support for this claim also comes from the observation that by metabolizing polyphenols (including those in brewed coffee), gut bacteria have the ability ‘to enhance the bioavailability of gut-derived, brain-penetrating, bioactive polyphenol metabolites that ultimately influence mechanisms associated with the promotion of resilience against psychological and cognitive impairment in response to stress,’” the author wrote.
These metabolites that cross the blood-brain barrier include the neurotransmitters serotonin, norepinephrine, GABA, and dopamine, which are deficient in those who have depression.
While there appears to be evidence supporting the notion that coffee consumption could combat depression, it should be noted that there can be too much of a good thing. Specifically, the FDA recommends that healthy adults consume no more than 4 to 5 cups per day.
For more information regarding other health effects of coffee, click here.