WARNING!
This is an older article that may not reflect Dr. Mercola’s current view on this topic. Use our search engine to find Dr. Mercola’s latest position on any health topic.
By Dr. Mercola
For the first time, a government advisory committee included a mention of caffeine in its recommendations for the 2015 edition of Dietary Guidelines for Americans.
Rather than suggesting it be eliminated, however, the report said Americans could safely consume up to five cups of coffee a day, or approximately 400 milligrams (mg) of caffeine, with no detrimental effects.1
It's a definite sign of the times. Coffee shop chains have been growing more than 10 percent annually, compared to 2 percent a year for fast food chains. There are about 20,000 coffee shops in the US, although 75 percent of the coffee brewed daily is actually consumed at home.2
Overall, more than 75 percent of US adults drink coffee, and 58 percent do so daily.3 Most coffee drinkers, however, did not start drinking coffee because they believed it was good for their health. In fact, many probably drink it assuming it is not.
If you're a coffee drinker, you're in for a pleasant surprise. There is one less dietary habit you have to worry about, as it turns out coffee may be good for you after all.
Even the 2015 Dietary Guidelines for Americans may soon reflect this, a recommendation that was based on an evaluation of multiple meta-analyses and other studies evaluating the link between coffee and chronic diseases, including cancer, type 2 diabetes, heart disease, Parkinson's, and Alzheimer's.
The more research that comes out, the more it seems clear that coffee – in its organic, black, and unadulterated form – is a beverage you can enjoy while benefitting your health.
Coffee May Be Good for Your Heart
The coffee plant and its seeds (coffee beans) contain a natural blend of polyphenol antioxidants (including chlorogenic acids), bioflavonoids, vitamins, and minerals that all work together to offer some impressive health-promoting benefits, and even help neutralize the harsher effects of the caffeine that coffee naturally contains.4
The first slew of studies has to do with coffee and heart health. One meta-analysis that included data from 11 studies and nearly 480,000 people found drinking two to six cups of coffee a day was associated with a lower risk of stroke.5 That study noted:
"The phenolic compounds in coffee possess antioxidant capacity and can inhibit the oxidative modification of low density lipoprotein cholesterol, thereby reducing the atherosclerotic process.
…moderate coffee consumption (1–3 cups/day in the United States or 3–4 cups/day in Europe) was associated with a significantly lower risk of coronary heart disease in women… Ample evidence also indicates that coffee consumption is inversely associated with risk of type 2 diabetes, which is a risk factor for cardiovascular disease."
Further, in a study of more than 25,000 people, those who drank a moderate amount of coffee – defined as three to five cups daily – were less likely to have calcium deposits in their coronary arteries than those who drank no coffee or more coffee daily.6
A large part of arterial plaque consists of calcium deposits (atherosclerosis), hence the term "hardening of the arteries." Coronary artery calcium can be a significant predictor of future heart disease risk.
In addition, one study showed moderate coffee drinking reduces your chances of being hospitalized for heart rhythm problems.7 Another study found it may trigger a 30 percent increase in blood flow in your small blood vessels, which might take some strain off your heart.8
Could Coffee Lower Your Risk of Cancer?
While a number of individual studies have suggested coffee consumption might increase your cancer risk, when multiple studies are analyzed, such as is the case with meta-analyses, the association disappears, and, in fact, becomes protective.
For instance, one 2007 meta-analysis found an increase in consumption of two cups of coffee per day was associated with a 43 percent reduced risk of liver cancer9 -- a finding that has been confirmed by more recent research.
Not to mention, coffee appears to have additional benefits for liver health, slowing down the progression of liver disease to cirrhosis, improving responses in people with hepatitis C, and lowering the risk of death in people with cirrhosis.10
The potential benefit of coffee for liver health appears so strong that researchers have stated daily coffee consumption should be encouraged in people with chronic liver disease.11
Another meta-analysis involving 59 studies revealed an increase in consumption of one cup of coffee per day was associated with a 3 percent reduced risk of cancers.12 According to the researchers, "coffee drinking was associated with a reduced risk of bladder, breast, buccal and pharyngeal, colorectal, endometrial, esophageal, hepatocellular, leukemic, pancreatic, and prostate cancers."13
There's even research showing coffee consumption could lower your risk of skin cancer. Drinking four cups of caffeinated coffee daily might reduce your risk of melanoma, the most dangerous form of skin cancer.14
According to researchers, "coffee constituents suppress UVB-induced skin carcinogenesis, induce cell apoptosis, protect against oxidative stress and DNA damage, reduce inflammation in epidermal cells, and inhibit changes in DNA methylation."15
Women who consumed more than three cups of coffee a day had a significantly lower risk of basal cell carcinoma (non-melanoma skin cancer) than those who consumed less than one cup per month.16
Coffee Has Multiple Potential Anti-Cancer Pathways
How might coffee lower cancer risk? Researchers noted in the journal BMC Cancer:17
"Roasted coffee is a complex mixture of more than a thousand chemicals. Many constituents in it could potentially alter cancer risk through several biological mechanisms. Coffee is the major source of caffeine which has been reported to both stimulate and suppress tumors, depending upon the species and the phase of administration.
There are two specific diterpenes in coffee, cafestol and kahweal, which produce biological effects compatible with anticarcinogenic properties, including the induction of phase II enzymes involved in carcinogen detoxification, specific inhibition of the activity of phase I enzyme responsible for carcinogen activation, and stimulation of intracellular antioxidant defense mechanisms.
Polyphenols are an important ingredient in coffee, such as lignan phytoestrogens and flavonoids and polyphenols are found to exhibit anticarcinogenic properties in several studies.
Caffeic acid has the ability to inhibit DNA methylation in cultured human cancer cells and is associated with inactivation of various pathways involved in the tumorigenic process, including cell cycle regulation, inflammatory and stress response and apoptosis.
Coffee is also a major source of the chlorogenic acid that contributes to its antioxidant effect. Intake of chlorogenic acid has been shown to reduce glucose concentrations in rats and intake of quinides, degradation products of chlorogenic acid, increases insulin sensitivity.
Chronic hyperinsulinemia and insulin resistance are confirmed markers of high risk for some cancer sites."
Coffee Might Benefit Your Brain Health and Lower Your Risk of Premature Death
In addition to the news that coffee might be good for your arteries, your liver, and your risk of cancer, several other studies have also yielded promising results regarding coffee and chronic disease. For instance:18
- Multiple Sclerosis: Drinking four to six cups of coffee a day is associated with a lower risk of multiple sclerosis, as is drinking a high amount of coffee over five to 10 years. According to researchers, "Caffeine has neuroprotective properties and seems to suppress the production of proinflammatory cytokines."19
- Dementia: Caffeine also promotes production of the neurotransmitters serotonin, dopamine, and noradrenaline, and triggers the release of brain-derived neurotrophic factor (BDNF), which activates brain stem cells to convert into new neurons, thereby improving your brain health.
Among people with mild cognitive impairment (MCI), those with higher blood levels of caffeine (due to coffee consumption) were less likely to progress to full-blown dementia.20 "Caffeine/coffee intake is associated with a reduced risk of dementia or delayed onset, particularly for those who already have MCI," the researchers said.
- Parkinson's Disease: Higher coffee and caffeine intake are associated with a lower risk of Parkinson's disease.21
Research published in the New England Journal of Medicine has even shown that coffee consumption is inversely associated with premature death. In other words, the more coffee drank, the lower the risk of death became, including deaths from heart disease, respiratory disease, stroke, injuries and accidents, diabetes, and infections.22
Tea Consumption Might Lengthen Your Life, Too
While there are more coffee drinkers than tea drinkers in the US (about 183 million compared to 173.5 million, respectively),23 many still enjoy sipping on tea …and this is another healthy habit. In fact, many centenarians around the world drink tea frequently, according to the Blue Zones project, which is documenting lifestyle habits of communities with high numbers of centenarians.24 As described in Dan Buettner's book, The Blue Zones Solution, in Okinawa, Japan, jasmine tea and green tea are popular.
On the island of Ikaria, another concentrated area for centenarians, tea is brewed daily using fresh-picked herbs, such as rosemary, wild sage, oregano, marjoram, mint or dandelion. When Buettner had the tea analyzed, he found anti-inflammatory and diuretic properties.25 Tea has been enjoyed for close to 5,000 years.
It was reportedly discovered in 2737 BC when tea leaves accidentally blew into Chinese Emperor Shen-Nung's pot of boiling water.26 Tea has been used traditionally as a beverage and healing tonic ever since. Like coffee, modern-day research has also confirmed tea's myriad of health benefits:
Reduced Mortality and Chronic Inflammation
Drinking green tea is associated with reduced mortality due to all causes, as well as mortality due to heart disease. Research also shows holistic benefits to green tea consumption, including lower blood pressure, oxidative stress, and chronic inflammation.27
Heart Health
Green tea improves both blood flow and the ability of arteries to relax, with research suggesting a few cups of green tea each day may help prevent heart disease.28 Study results also show EGCG can be helpful for the prevention of arteriosclerosis, cerebral thrombus, heart attack, and stroke—in part due to its ability to relax your arteries and improve blood flow.29
Type 2 Diabetes
One study found people who consume six or more cups of green tea daily had a 33 percent lower risk of developing type 2 diabetes than those who consumed less than one cup per week.30
Weight Loss
There is some evidence that long-term consumption of green tea catechins is beneficial for burning fat and may work with other chemicals to increase levels of fat oxidation and thermogenesis.
Bone Health
Green tea polyphenols combined with a form of vitamin D called alfacalcidol could boost bone structure and strength, according to a new study in mice. The mixture may reverse damage to bones caused by lipopolysaccharide (LPS) induced chronic inflammation, which could in turn reduce the risk of osteoporosis.31
Vision Health
Catechins in green tea could help protect you against glaucoma and other eye diseases, as research found that the compounds travel from your digestive system into the tissues of your eyes. During the study, the catechins found in green tea were absorbed into various parts of the eyes anywhere from 30 minutes to 12 hours after rats were given tea.32
Cancer
Green tea components have been shown to downregulate the expression of proteins involved in inflammation, cell signalization, cell motility and angiogenesis, while an association between green tea intake and decreased risk of cancers (including ovarian and breast33) have been reported.34
Previous research has shown that green tea polyphenols act on molecular pathways to shut down the production and spread of tumor cells.35 They also discourage the growth of the blood vessels that feed the tumors. EGCG even acts as an antiangiogenic and antitumor agent, and helps modulate tumor cell response to chemotherapy.36
If You Drink Tea, Be Careful of Contaminants
Green tea plants are known to be especially effective at absorbing lead from the soil, which is then taken up into the plants' leaves. Areas with excessive industrial pollution, such as China (where nearly 90% of the world's green tea is produced),37 may therefore contain substantial amounts of lead.38
While the lead in the tea leaves is not thought to leach very effectively into the tea you end up drinking, if you're consuming Matcha green tea (which contains the entire ground tealeaf), one of my favorites, it's especially important that it comes from Japan instead of China.
Both black and green teas are also naturally high in fluoride, even if organically grown without pesticides. This is because the plant readily absorbs fluoride thorough its root system, including naturally occurring fluoride in the soil.
According to fluoride expert Jeff Green, who sadly passed away unexpectedly last year,39 there are reports of people who have developed crippling skeletal fluorosis from drinking high amounts of iced tea alone.40 If you live in an area with fluoridated drinking water, as the majority of Americans do, then you could be getting a double dose of fluoride when you drink tea.
When selecting tea of any kind, it should preferably be organic (to avoid pesticides) and grown in a pristine environment because, as mentioned, tea is known to accumulate fluoride, heavy metals, and other toxins from soil and water. A clean growing environment is essential to producing a pure, high-quality tea. Another quick tip? Add a squirt of lemon juice to your cup. Previous research has demonstrated that vitamin C significantly increases the amount of beneficial catechins available for your body to absorb.
On the other hand, while adding lemon juice is beneficial, adding milk is not. The proteins in milk may bind to and neutralize the antioxidants in tea, such that its health benefits are significantly reduced."41
The Healthiest Coffee Is Black and Organic
For many people today, "coffee" has become synonymous with heavily sweetened, chocolate-, vanilla-, or caramel-flavored beverages. But if you are dousing your cup of Joe in creamer, non-dairy creamer, sugar, and other sweeteners and flavorings, you are missing out on the therapeutic benefits and potentially harming your health. The natural blend of polyphenol antioxidants are part of what makes coffee so healthy.
However, some research suggests that adding dairy to your coffee may interfere with your body's absorption of beneficial chlorogenic acids.42 Meanwhile, if you add sugar to your coffee you'll spike your insulin levels, which contributes to insulin resistance.
If you're interested in the health benefits, drink your coffee black, without sugar, non-dairy creamer or cream, or flavorings. If you really can't stand your coffee black, you could try adding non-dairy alternatives like coconut milk or a natural sweetener like stevia.
As for buying organic, do so whenever possible. Coffee beans are one of the most heavily pesticides-sprayed crops. So, you should select only coffee beans that are certified organic. Remember, you will obliterate any positive effects if you consume coffee that's been doused in pesticides or other chemicals.
Whenever possible, purchase sustainable "shade-grown" coffee to help prevent the continued destruction of our tropical rain forests and the birds that inhabit them. There are many who say shade-grown coffee tastes better as well. In addition, you'll want to purchase whole bean coffee that smells and tastes fresh, not stale; if your coffee does not have a pleasant aroma, it is likely rancid.
Grind it yourself to prevent rancidity, as pre-ground coffee may be rancid by the time you get it home. If you use a "drip" coffee maker, be sure to use non-bleached filters. The bright white ones are chlorine-bleached, and some of this chlorine will leach from the filter during the brewing process.
Bleached filters are also notoriously full of dangerous disinfection byproducts, such as dioxin. Finally, while it appears coffee in moderation is beneficial, be careful not to overdo it, as some studies have found adverse effects when about 10 cups a day or more are consumed. When referring to a "cup" of coffee, most research considers it to be five to eight ounces with about 100 mg of caffeine.
In contrast, a small cup at many coffee houses starts at 12 ounces while a large cup may hold 20-24 ounces. Finally, pregnant women should probably not drink caffeinated coffee. Public health agencies suggest pregnant women limit daily caffeine to 200 mg (or about two cups of coffee a day).
However, caffeine can significantly impact the growing fetus. It is able to freely pass through the placenta, and since caffeine does not provide any benefits to your baby, only potential hazards, I strongly recommend pregnant women avoid ALL forms of caffeine.