Nutrition Notes

Chlorogenic Acid—Green Coffee Polyphenol

There’s a lot of buzz about the health benefits of green tea, but what about green coffee beans? The health benefit versus risk ratio of coffee continues to be hotly debated. Although the opposing sides both have legitimate arguments for their position (and the ultimate conclusion is highly individual), we are going to focus on one of the chief health-promoting substances in coffee, chlorogenic acids. But don’t despair if you’re not a coffee drinker; you don’t have to drink coffee to receive the benefits of these compounds. In fact, they’re probably most useful when extracted from their source and taken directly.

Chlorogenic acids are powerful polyphenols found in coffee beans in varying amounts depending on the species, roasting time and technique. Since roasting decreases the activity of chlorogenic acids, green coffee beans offer the highest content of these compounds, 82 individual ones of which have been identified. The biological activity of chlorogenic acids (a.k.a. green coffee bean extract) has been well-studied and is associated with a variety of health benefits and decreased risk factors for chronic disease. A 2017 systematic review of clinical trials in the European Journal of Nutrition focused on the effects of chlorogenic acid on cardiovascular, metabolic, neurological and other functions and found this polyphenol not only exhibits the traditional antioxidant and anti-inflammatory activities of most dietary polyphenols, but uniquely plays roles in modulating glucose and lipid metabolism. A 2018 review in Biomedicine & Pharmacotherapy found chlorogenic acids to be antibacterial, hepatoprotective, cardioprotective, antipyretic, neuroprotective, anti-obesity, antiviral, anti-microbial, anti-hypertensive, and a central nervous system stimulator.

The bioavailability of chlorogenic acid appears to be highly dependent on its metabolism by gut microflora. After consumption, approximately one-third is absorbed in the small intestine and the remainder arrives in the colon, where it is hydrolyzed by esterases produced by Bifidobacterium and Lactobacillus species. The microflora metabolites diffuse across colonic cell membranes and enter the circulation.

Metabolic Syndrome

According to a 2017 review that explored the roles of chlorogenic acids in managing metabolic syndrome, the efficacy of these dietary polyphenols is rooted in their multifaceted roles. These acids were found to significantly reduce body weight, visceral fat mass, plasma leptin and insulin levels, triglycerides in liver and heart, cholesterol in adipose tissue and heart, blood pressure, and significantly improved the HDL/total cholesterol ratio. Additionally, a significant decrease in glucose-dependent insulinotropic polypeptide (GIP) and increase in glucagon-like peptide 1 (GLP-1) secretion following chlorogenic acid consumption helps to positively regulate glucose transport. Further, postprandial energy expenditure was higher, leading to greater fat utilization. Obesity, dyslipidemia, and impaired glucose metabolism are significant markers for metabolic syndrome; as chlorogenic acids target all these risk factors, it may be a candidate for helping to manage this chronic health condition.

Mental Health

Chlorogenic acids not only help improve metabolic and cardiovascular health, but they also offer substantial benefits for mental health due to their neuroprotective effects. Many neurodegenerative diseases, such as Alzheimer’s and Parkinson’s diseases, as well as mood disorders such as depression, are associated with neuroinflammation and oxidative stress. Chlorogenic acids cross the blood brain barrier where they scavenge free radicals and help to increase the expression of neuroprotective ribosomal proteins (PEP-1-rpS3). When human neuroblastoma cells were pretreated with chlorogenic acid, they were able to retain viability despite being treated with β-amyloid proteins, the buildup of which characterizes Alzheimer’s disease and may decrease cell viability. Likewise, chlorogenic acid was shown to protect against α-synuclein-induced toxicity characteristic of Parkinson’s disease. Further actions by which chlorogenic acids protect the brain against neurodegeneration and mood changes include lowering the activities of acetylcholinesterase and butyrylcholinesterase and maintaining acetylcholine levels in the synapses.

Oxidative and Inflammatory Stress

Among the most valuable attributes of chlorogenic acids are their antioxidant and anti-inflammatory properties. Considering the plethora of chronic health conditions rooted in oxidative and inflammatory stress, the potential positive health outcomes from these activities are far-reaching. In human cell-based assay studies, chlorogenic acids directly reduced lipid peroxidation, the formation of reactive oxygen species, and prevented glutathione depletion. They also reduced X-ray irradiation-induced DNA damage to human blood lymphocytes by approximately 5-48%.

In addition to their antioxidant activities, chlorogenic acids suppress inflammation by inhibiting proinflammatory cytokines such as IL-8, IL-6, and TNF-α, as well as downregulating the NF-κB pathway. A cell study showed chlorogenic acid suppressed lipopolysaccharide-induced COX expression in mouse macrophages, thereby reducing eicosanoid production.

It’s hard to argue against the health benefits of chlorogenic acids, which are most reliably sourced from green coffee, although they can also be found in pears, apples, endive, and various herbs. As we consider their role in helping to manage a variety of chronic health conditions through their ability to reduce oxidative and inflammatory stress, chlorogenic acids are an intriguing dietary polyphenol.