Coffee is a brewed drink and one of the most common beverages consumed worldwide.
Coffee is prepared from roasted coffee beans, which are the seeds of certain Coffea plants that originate in Africa and Asia.
Containing a huge range of over 1000 bioactive compounds, coffee has been linked to possessing antioxidant, anti-inflammatory, and anticancer effects.
Active components of coffee are reported to be caffeine, chlorogenic acids, cafestol and kahweol.
However, this is largely dependent on the composition of the beans used and how the coffee is prepared.
Thankfully, as coffee is such a popular drink, vast amounts of research have been conducted to analyze its physiological effects and any potential safety concerns.
1. It Can Help Reduce The Risk of Diabetes
Several recent studies and meta-analyses have demonstrated an inverse association of coffee consumption with the incidence of diabetes .
Increasing coffee intake by ≥1 cup per day can decrease type 2 diabetes risk by ~10%, whilst decreasing coffee intake by >1 cup per day can increase type 2 diabetes risk by ~15%.
The components within coffee that improve insulin sensitivity – effectively using insulin to maintain normal blood sugar levels – and reduce diabetes risk are chlorogenic acid, quinides, lignans, and trigonelline.
These substances, especially chlorogenic acid, act by raising the levels of adiponectin in the body – a protein hormone involved in regulating glucose levels – which is associated with improved insulin sensitivity by binding to insulin receptors and mediating its activity.
Studies confirm chlorogenic acids critical role in glycemic control, insulin secretion, and insulin sensitivity, with an impressive ability to reverse the impairment of glucose tolerance .
It is speculated that chlorogenic acid may also improve glucose absorption by inhibiting enzymes involved in glucose metabolism, thus avoiding hyperglycaemic events (excess blood sugar), in order to protect insulin-producing cells.
2. It Can Lower Blood Pressure
The risk of hypertension has been found to reduce by ~2% with each one cup of coffee per day, however the benefit is limited beyond ~6 cups per day .
One of the mechanisms by which coffee lowers blood pressure is by caffeine having a diuretic effect, causing increases in urine excretion which allows for reduced pressure on blood flow .
Coffee’s ability to improve the actions of insulin may also have similar effects, as improved insulin action can reduce fluid retention and thus lower the pressure on capillaries .
Chlorogenic acids may also improve endothelial and vascular function through the increased availability of nitric oxide, which allows for blood vessels to relax and dilate.
The vitamin E, niacin, potassium and magnesium content also provide coffee with some degree of blood pressure lowering effects, along with caffeine metabolites such as flavonoids and melanoidins which may act as antihypertensives.
3. It May Help Protect Against Cancer
Studies have revealed that coffee drinkers have a ~15% lower relative risk of developing cancer .
In addition, there has been a recorded ~2% lower risk of mortality from cancer for each additional cup of coffee consumed per day .
Coffee seems to have most relevance to cancer prevention in prostate, endometrial, oral, and liver cancer. No positive links have been found for gastric, colorectal, colon, rectal, ovarian, thyroid, breast, and pancreatic cancer.
Despite the analyses’ of coffee’s protective effect on cancer, the exact physiological mechanisms are not fully understood.
The ability for the polyphenols in coffee to exhibit antioxidative properties such as reducing oxidative stress and DNA damage is the most likely method to cancer prevention.
Although it may not seem like coffee is a major contributor to antioxidant intake, in countries such as Finland and Norway it can provide >50% of total dietary antioxidants.
Diterpenes within coffee, such as cafestol and kahweol, have also shown to modulate multiple enzymes involved in carcinogenic detoxification. This could potentially suppress cancer gene expression and inhibit cell proliferation .
4. It Can Help with Depression
There is a significant association between coffee consumption and the risk of depression, with a decreased risk at intakes up to ~600ml per day .
As depression is heavily linked to low-grade inflammation, compounds such as chlorogenic acid and catechins reduce symptoms of depression by exhibiting antioxidant and anti-inflammatory actions.
Catechins in particular may potentially hold unique antidepressant-like effects such as regulating nervous system activity in the brain and aiding neural connectivity .
The high caffeine content is also suggested to play a role by facilitating dopamine and serotonin release – a neurotransmitter that regulates mood and social behavior.
Trigonelline and pyrogallol within coffee further stimulate this dopamine release – a neurotransmitter involved in the motivational component of reward-motivated behavior.
5. It Can Help Increase Longevity
Studies indicate a lower relative risk for all-cause mortality, compared to non-coffee drinkers, of ~5% for 1 cup of coffee, ~10% for 2-3 cups, ~12% for 4-5 cups, and ~13% for 6 or more cups .
Lower risks of mortality are unsurprising given the significantly reduced risk of diabetes, cardiovascular disease, cancer, and depression.
The lower risk of death primarily comes from reduced mortality from digestive and circulatory diseases.
The inverse relationship between coffee consumption and mortality is stronger in women compared to men, with the difference between sexes driven by much stronger associations for reduced cerebrovascular (brain condition) mortality risks in women.
Coffee has a lot of research that associates its consumption with a decreased risk of many diseases such as cardiovascular disease, diabetes, cancer, and depression.
These benefits are mainly reported to be due to the caffeine, chlorogenic acid, cafestol and kahweol content of coffee.
There seems to be a maximum threshold to where coffee does not contribute to any more positive effects compared to more moderate intakes.
It is advised to consume between 1-5 coffees per day to see these benefits.