Coffee's antioxidant and protective benefits - research
What is coffee?
The benefits of drinking coffee
Coffee and your liver (especially if you drink alcohol)
Warnings about coffee
What is coffee?
Coffee, an infusion of ground and roasted coffee beans, is one of the most widely consumed beverages in the world. Although the negative effects of caffeine have received the most attention from health writers, coffee is a complex mixture of chemicals, many of which are beneficial to our health.
A ground and brewed cup of coffee is a rich source of antioxidants and other healthy compounds. This is good news for the 80% of Americans who drink coffee - downing an average of 3.2 cups per day. About 54% of adults in the USA drink coffee every day. In countries such as Germany, Austria, and Finland adults drink twice as much as those in the United States.
Populations consuming a modern diet of refined and processed foods suffer obesity, heart disease and a host of other degenerative diseases. Is a high level of coffee consumption contributing to the problem? The answer is that in excess it may. But I'm glad to say that regular and moderate coffee consumption is a good protection against many of these diseases. (32, 34, 35, 36)
One of the best ways to protect yourself from degenerative diseases such as cardiovascular disease, diabetes and cancer is to eat a diet rich in antioxidants. But many of us do not eat enough fresh vegetables and fruit - the best source of antioxidants. Guess where many people are getting their antioxidants instead? Coffee, several studies say (2, 3, 4, 15, 17, 25, 31). In fact, coffee is the top dietary source of antioxidants for most people in the USA and in many European countries..
This is in addition to studies discussed in Grow Youthful that show that regular drinkers of black tea, green tea and coffee have substantially lower 'all causes' death rates than non-drinkers (25, 32, 34, 35). Several of these studies (19, 32, 34, 35, 36) showed that the lower mortality of coffee drinkers included less heart disease.
Coffee is a rich source of amino acids, vitamins, minerals, alkaloids and phenolic compounds. It also contains a range of antioxidants, caffeine and other yet-to-be researched compounds. It seems that coffee has several health benefits, although most of the research is in the early stages.
Roasted coffee residues retain their antioxidant ability; it isn't lost in processing.
If you don't already drink coffee, the news about antioxidants is probably not a good enough reason to start the habit. And if you already drink it, it's no excuse to stop eating fruits and vegetables.
Your best bet is to eat your fruits and veggies, and consume between one and three cups of coffee per day. That way you will consume no more than 250 milligrams of caffeine per day, the limit recommended by most of these studies.
The benefits of drinking coffee
All the benefits of coffee apply to black coffee. As explained in Grow Youthful, adding milk and sweeteners turns it into a harmful beverage. If you absolutely have to have white coffee, then use full-fat cream.
Please avoid coffee with dairy milk, cappuccinos, coffee made with soy milk, "skinny" coffee made with low-fat milk, and other harmful processed food techniques.
- Habitual drinking of coffee is beneficial for the heart and arteries, compared to occasional drinking (8,17,29,32). Up to five cups of coffee per day protect against cardiovascular disease (29,32). High coffee consumption is a cause of cardiovascular disease (9).
- Habitual coffee consumption gives you a lower risk of type 2 diabetes (10,31).
- Men may experience up to a 40% reduction in risk of Parkinson's disease by drinking as little as one cup per day (11,13,14,16,32). However, the effects were not observed in postmenopausal women who take estrogen replacement. In this case, coffee drinking may actually increase Parkinson's risk.
- Adults who drank one or more cups of coffee a day were half as likely to develop cancer of the mouth, pharynx, and oesophagus compared with people who didn't drink coffee (1, 27). Caffeine protects against skin cancers such as basal cell carcinoma (26).
- Coffee reduces your rate of insulin secretion (6,31). This is most beneficial, as Grow Youthful emphasises that insulin overload is one of the root causes of rapid aging and many degenerative diseases, especially obesity.
- Coffee decreases your risk of liver cancer (12,18,30). Drinking coffee may be especially helpful reducing the risk of liver cancer caused by cirrhosis, a type of liver disease that causes scarring of the liver. Two cups of coffee per day lower your risk of liver cancer by more than 40%. (30)
- Women who drank 2-3 cups a day were 19% less likely to have a stroke compared with women who drank less than one cup a month. However, this benefit only applied to non-smoking women with no history of high blood pressure, high cholesterol, or diabetes. A meta-analysis in 2012 found a substantial reduction in the risk of stroke from drinking four cups of coffee per day, (33) confirmed by larger studies in 2017 and 2018. (34, 35, 36)
- Middle-aged adults who reported drinking at least 3 cups of coffee a day were 65% less likely to have developed dementia or Alzheimer's by the time most of the group had reached their mid-sixties to seventies. (28, 32)
Coffee and your liver (especially if you drink alcohol)
Those people who regularly drink coffee have healthier livers. (18, 34, 35)
Your liver is your major blood-cleansing organ in your body, removing all sorts of toxins including alcohol. It stores energy, fat-soluble vitamins, and other nutrients. It helps construct proteins, bile, and other essentials. You need a healthy liver for a long life.
Scientists measured the level of certain enzymes that show liver damage, and discovered that regular coffee drinkers have substantially lower levels of these enzymes. Ground and roasted coffee is a rich source of antioxidants, and seems to have other beneficial compounds.
Coffee's protective effect was most pronounced in those who are moderate to heavy drinkers of alcohol.
Note that alcohol can be particularly damaging to the liver, and coffee can NOT make up for the damage that long-term heavy alcohol consumption does to the liver.
Warnings about coffee
Coffee is high in Caffeine, an addictive, dehydrating, diuretic drug that upsets your blood glucose level, your insulin levels, your digestion, and several other body processes. Do not expect good health and a long life if you are drinking an excessive level of caffeine - also added to soft drinks (because it is addictive), and found in black tea and cacao (chocolate or cocoa).
Caffeine does however, have some anti-cancer benefits.
Several major meta studies of coffee drinkers found that coffee's protective benefits apply to both caffeinated and caffeine-free coffee. In addition, the benefits of drinking coffee do not vary by country. This suggests that the benefits of drinking coffee are independent of the methods of preparation and different drinking habits across countries. (32, 34, 35, 36)
As usual, how much coffee to drink comes back to this golden rule called MODERATION. I enjoy a cup of high quality, fresh-brewed (Bali coffee style) coffee every morning, and it feels good. If you are drinking more than one or two cups per day, you may be drinking too much. A good test is to stop drinking coffee for a few days. If you find this difficult to do, and get a headache or a drop in your energy level, then you are addicted and it is already negatively affecting your health.
Avoid soft drinks / soda / sports drinks / caffeinated drinks and other sources of caffeine if you suffer from the ailments below. However, the evidence for negative effects of unsweetened black coffee and black tea is less clear.
- Metabolic syndrome (fatigue, depression, anxiety, inflammation, tendency to overweight - discussed in Grow Youthful).
- Insomnia or a nervous and sensitive disposition.
- Hypertension (high blood pressure).
- Arrhythmia or rapid heartbeat. Although moderate coffee consumption lowers your risk of cardiovascular disease, research shows that chronic consumption may increase aortic stiffness.
A Greek study (5) shows that high coffee consumption leads to inflammation. However, another large and more recent study (31) shows just the opposite, that coffee is actually beneficial for inflammatory markers. Researchers (7) showed that regular caffeine consumption increases blood pressure, however if the caffeine comes from coffee, the effect is much smaller than otherwise. This again confirms that there are as yet unknown protective ingredients in coffee.
Tea, as discussed on other pages on the Grow Youthful website, is a brew with multiple health benefits. Tea's main protectors are antioxidant flavonoids. It contains less caffeine than coffee. Green tea can contain anywhere from 9 to 50 milligrams per cup while black tea typically contains between 42 to 72 milligrams.
The well-established benefits of tea include:
- decreased risk of LDL cholesterol oxidation and improved blood fats, leading to a decreased risk of heart attack and stroke.
- decreased risk of Parkinson's disease.
- decreased risk of Alzheimer's disease.
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Toru Naganuma; Shinichi Kuriyama; Masako Kakizaki; Toshimasa Sone; Naoki Nakaya; Kaori Ohmori-Matsuda; Yoshikazu Nishino;
Akira Fukao; Ichiro Tsuji.
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11. Coffee consumption, gender, and Parkinson's disease mortality in the cancer prevention study II cohort: the modifying effects of estrogen. Ascherio, A., Weisskopf, M.G., O'Reilly, E.J., McCullough, M.L., Calle, E.E., Rodriguez, C., Thun, M.J., American Journal of Epidemiology 2004 Nov 15;160(10):977-984
12. Coffee consumption reduces the risk of hepatocellular carcinoma independently of its aetiology: a case-control study. Gelatti, U., Covolo, L., Franceschini, M., Pirali, F., Tagger, A., Ribero, M. L., Trevisi, P., Martelli, C., Nardi, G., Donato, F.; Brescia, HCC Study Group, Journal of Hepatology 2005 Apr;42(4):528-534
13. Dose-dependent protective effect of coffee, tea, and smoking in Parkinson's disease: a study in ethnic Chinese. Tan, E. K., Tan, C., Fook-Chong, S. M., Lum, S. Y., Chai, A., Chung, H., Shen, H., Zhao, Y., Teoh, M. L., Yih, Y., Pavanni, R., Chandran, V. R., Wong, M. C., Journal of Neurological Sciences 2003 Dec 15;216(1):163-167
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17. Role of antioxidants in atherosclerosis: epidemiological and clinical update. Cherubini, A., Vigna, G. B., Zuliani, G., Ruggiero, C., Senin, U., Fellin, R., Current Pharmaceutical Design 2005;11(16):2017-2032
18. Coffee, cirrhosis, and transaminase enzymes. Klatsky, A. L., Morton, C., Udaltsova, N., Friedman, G. D., Archives of Internal Medicine 2006 Jun 12;166(11):1190-1195
19. The relationship of coffee consumption with mortality. Lopez-Garcia, E. et al., Annals of Internal Medicine 2008 Jun 17;148(12):904-914
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23. Green tea and the risk of colorectal cancer: pooled analysis of two prospective studies in Japan. Suzuki, Y., Tsubono, Y., Nakaya, N., Koizumi, Y., Suzuki, Y., Shibuya, D., Tsuji, I. Journal of Epidemiology 2005 Jul;15(4):118-124
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26. Increased caffeine intake is associated with reduced risk of basal cell carcinoma of the skin. Song F, Qureshi AA, Han J. Cancer Res. 2012 Jul 1;72(13):3282-9. doi: 10.1158/0008-5472.CAN-11-3511.
27. Coffee, Tea, and Fatal Oral/Pharyngeal Cancer in a Large Prospective US Cohort. Janet S. Hildebrand, Alpa V. Patel, Marjorie L. McCullough, Mia M. Gaudet, Amy Y. Chen, Richard B. Hayes, Susan M. Gapstur. Am. J. Epidemiol. (2012) doi: 10.1093/aje/kws222 First published online: December 9, 2012.
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29. Ming Ding, Shilpa N. Bhupathiraju, Ambika Satija, Rob M. van Dam, Frank B. Hu. Long-Term Coffee Consumption and Risk of Cardiovascular Disease. A Systematic Review and a Dose-Response Meta-Analysis of Prospective Cohort Studies Circulation 2014; 129: 643-659. Published online before print 7 November 2013. doi: 10.1161/CIRCULATIONAHA.113.005925.
30. Francesca Bravi, Cristina Bosetti, Alessandra Tavani, Silvano Gallus, Carlo La Vecchia. Coffee Reduces Risk for Hepatocellular Carcinoma: An Updated Meta-analysis. Clinical Gastroenterology and Hepatology, Volume 11, Issue 11, 1413 - 1421.e1. Published Online: May 08, 2013.
31. E Koloverou, D B Panagiotakos, C Pitsavos, C Chrysohoou, E N Georgousopoulou, A Laskaris, C Stefanadis. The evaluation of inflammatory and oxidative stress biomarkers on coffee-diabetes association: results from the 10-year follow-up of the ATTICA Study (2002-2012). European Journal of Clinical Nutrition, (1 July 2015) | doi:10.1038/ejcn.2015.98.
32. Ming Ding, Ambika Satija, Shilpa N. Bhupathiraju, Yang Hu, Qi Sun, Jiali Han, Esther Lopez-Garcia, Walter Willett, Rob M. van Dam, and Frank B. Hu. Association of Coffee Consumption with Total and Cause-Specific Mortality in Three Large Prospective Cohorts. Circulation. 2015; published online before print 16 November 2015. doi:10.1161 / CIRCULATIONAHA.115.017341.
33. Byungsung Kim, Yunjung Nam, Junga Kim, Hyunrim Choi, Changwon Won. Coffee Consumption and Stroke Risk: A Meta-analysis of Epidemiologic Studies. Korean J Fam Med. 2012 Nov; 33(6): 356-365. Published online 27 Nov 2012.
34. Gunter Mark J, Murphy N, Cross AJ et al., (2017). Coffee drinking and mortality in ten European countries - the EPIC Study. Annals of Internal Medicine. Accepted 18 May 2017.
35. Song-Yi Park, Neal D. Freedman, Christopher A. Haiman, Loic Le Marchand, Lynne R. Wilkens, Veronica Wendy Setiawan. Association of Coffee Consumption With Total and Cause-Specific Mortality Among Nonwhite Populations. Published 11 July 2017.
36. Erikka Loftfield, Marilyn C. Cornelis, Neil Caporaso, Kai Yu, Rashmi Sinha, Neal Freedman. Association of Coffee Drinking With Mortality by Genetic Variation in Caffeine Metabolism. Findings From the UK Biobank. JAMA Intern Med. Published online July 2, 2018. doi:10.1001/jamainternmed.2018.2425.