There have been rumors that caffeine in coffee can prevent diabetes. This is a pretty tall order (or should I say venti?) for roasted seeds. With diabetes rates climbing alongside America’s coffee addiction, it seems impossible. After pouring through hundreds of studies on disease risk and prevention, I found one common theme around caffeine: it’s a complex brew.
Diabetes prevention – yes and no
New research that started the buzz showed that high consumption of caffeinated coffee in postmenopausal women associated with higher SHBG, indicating lowered risk for diabetes. Before you pour an extra cup, realize that this study did not show if caffeine alone can change SHBG or come close to preventing diabetes.
French scientists cleverly identified that the benefits between caffeine and diabetes prevention were higher when caffeinated or decaffeinated black coffee was consumed at lunch rather than other times of day. This interesting pattern may be explained by the compounds in coffee that affect food metabolism. When milk was added to coffee, the beneficial effects were eliminated. There are many contradictory findings on the interaction between milk and the polyphenols in coffee and tea, though added milk has potential to react or interfere with health benefits.
A second less publicized review in April cautioned that caffeine actually increased the risk of diabetes through glucose intolerance, confusing all of the doctors in line at Starbucks. Caffeinated coffee isn’t the only offending beverage here. Another study showed that decaffeinated coffee also impaired glucose metabolism, though less than caffeine. Most of us already know that fructose sweetened beverages have adverse effects on lipids and insulin sensitivity.
Protection from inflammatory disease – with reservations
Coffee is a common source of antioxidants like caffeine, polyphenols, volatile aroma compounds and heterocyclic compounds that contribute to its health benefits. Coffeemakers vary in their production of antioxidants. One study confirmed that espresso produced the most, with additional antioxidant content in browned and caffeinated brews.
These antioxidants may help reduce inflammation, as revealed in the study comparing beverages with mortality risk disease in postmenopausal women. The benefits on cardiovascular disease were more significant with 1-3 daily cups of caffeinated and <1 daily cup decaffeinated coffees. Mortality risk soared with several daily cups of diet beverages and sugar-sweetened drinks.
Yet the stimulating effects of caffeine might reduce the health benefits in other cases. Heavy coffee consumption was associated with short-term heart attack risk. One team discovered inflammatory responses to mental stress associated with habitual coffee consumption. While caffeine lowered certain inflammatory markers in mice in one study, it increased lung inflammation in newborn mice in another. We need more research to determine when and how caffeine or coffee can reduce inflammation and disease with respect to specific conditions.
Caffeine and cortisol – a dark roast
While scientists were trying to unlock health secrets in caffeine consumption, they discovered a more insidious problem with the stimulant. Caffeine disrupts levels of cortisol in the body which control aspects like thyroid function, blood sugar, bone density, blood pressure, immune responses, and abdominal fat, to name a few. New research showed that caffeine prevented cortisol levels from falling normally. Tolerance does not prevent this effect, as the elevation of cortisol occurred even with regular caffeine consumption.
While we do not yet understand the mechanism behind this effect, caffeine’s interference with cortisol is an important factor when weighing each individual’s health risk.
Coffee-cancer links – liver, not lung
In fighting cancers, coffee appeared to benefit the liver the most. Research in Singapore found that drinking 3 or more daily cups of coffee was associated with 44% reduction of liver cancer. Coffee drinking also associated with a reduced risk of endometrial cancer in Sweden. These studies did not determine if caffeine played a role in the outcome.
Risk of brain or spinal tumors (glioma) was decreased in heavy consumption of caffeinated coffee and tea (5 or more cups). A reduced risk of pancreatic cancer was also seen among men who consumed high levels.
New investigations are revealing how coffee brewing methods might be affecting these results. Boiled coffee (not filtered) was associated with higher risk of respiratory cancer in men. In contrast, boiled coffee was linked to reduced risk of breast cancer. Another study showed that cholesterol levels were increased with boiled coffee and not filtered.
In a large Indian study, coffee and tea drinking was associated with a significant risk of lung cancer. (Interestingly, reduced fat milk was associated with reduced risk of lung cancer while whole milk consumption increased the risk in this study and one in the US.) Another study found that caffeine may contribute to growth of lung cancer cells. It is not clear how caffeine may interact with other factors like smoking, alcohol, and pesticide exposure to increase or decrease total risk of lung cancer.
Blood pressure increases – take a seat
Much research shows that caffeine increases blood pressure, though the extent of increase depends on many factors. A new study revealed that blood pressure increases were larger after low caffeine consumption when people were upright rather than lying down. Interestingly, this effect disappeared when caffeine consumption was higher at 200 mg/day (about 2 cups of coffee), indicating some tolerance.
Caffeine tolerance adds a dose of confusion to the mystery. While many people assume that tolerance to caffeine might protect them from negative health effects, studies are proving this false. For example, daily caffeine consumption did not change the spike in blood pressure on half of adults tested, even at regularly high levels.
Effects on the brain – mind-boggling results
Caffeine appeared to lower risk of Parkinson’s disease in people carrying certain genes who metabolize caffeine slowly. Caffeine intake may also associate with a reduced risk for Alzheimer’s disease. New research hints at a mystery ingredient in coffee that interacts with caffeine to provide protection from Alzheimer’s – unlike other caffeinated beverages or decaffeinated coffee.
Brains appear to benefit from caffeine in other ways as well. One study found that caffeine intake was linked to fewer white matter lesions in the brain. These clumps of dead cells reduce our processing power and memory. This protection was limited to women consuming more than 300 mg of caffeine per day (about 3 shots of espresso), though the reasons are unclear.
Yet other research found that socioeconomic status had a bigger impact on cognitive performance than caffeine consumption. Professional or administrative work with more education had a greater, positive impact than long-term coffee drinking.
Most interestingly, a military pilot study showed that caffeine created overconfidence and the incorrect perception of improved cognitive performance. One study calls this pre-existing expectancy, confirming that caffeine only enhanced performance when participants were told they were receiving it!
Sleep – cut the caffeine to cut the z’s
Large studies show that caffeine disturbs the sleep cycle, creates daytime sleepiness, and prevents proper rejuvenation. When we think caffeine is enhancing our performance in the morning, it’s actually restoring energy that is lost due to poor sleep. Sleep is critical for our immune health in ways we do not completely understand.
Sleep deprivation is also associated with the elevation of IL-6, an inflammation marker. Caffeine was linked to increased levels of IL-6 in sleep-deprived subjects, and both sleep deprivation and increased IL-6 were associated with chronic back pain in a recent study.
Physical performance – a strong brew
Exercise science has been studying how caffeine affects performance in athletes for some time, though again the results are mixed. High doses of caffeine enhanced strength but not endurance in resistance-trained women. One review concluded that there is some supporting evidence for using caffeine in resistance training. Other benefits are limited to team or power-based performance among elite athletes who do not use caffeine regularly. Most studies on exercise reveal very little consistency, particularly across different sports, exercises, and groups of athletes. Save your money on caffeine-laced energy drinks or snacks and buy new exercise shoes instead!
Tea time – go green
Some of the benefits of coffee are shared by tea which contains less caffeine. For example, green tea inhibits inflammation in test studies, even in decaffeinated form. One study showed reduced risk of cardiovascular death from caffeinated green and oolong teas, particularly for men. Green tea also protects skin from the damaging effects of UV radiation. Studies are showing possible benefits for green tea in reducing or preventing many different cancers including upper gastrointestinal tract, lung, liver, prostate, and breast. These benefits are not shared by black tea.
No clear association has been made between coffee and breast cancer despite many studies.
The drug we don’t talk about
Despite its popularity and potential for treating certain conditions, caffeine is an addictive drug that creates dependence, tolerance, and withdrawal. Anyone who tries to eliminate their caffeine habit may experience typical drug withdrawal symptoms like irritability, headaches, muscle tremors, and arrhythmias. Symptoms occur 12-24 hours after stopping consumption and can last between 2 days and a week.
The consumption, addiction, and effects of caffeine may vary greatly between individuals, and this difference may be largely due to genetics according to new studies. A lifetime of caffeine addiction may also represent a genetic risk for other drug dependencies. Even in adolescents, caffeine consumption was associated with other substance abuse and daytime sleepiness.
Caffeine is one of three classes of methylxanthines that help dilate airways, stimulate urination, and stimulate the cardiac and nervous system. Caffeine is found in coffee, tea, cola nuts, and minimally in cacao. Caffeine is about 3 times higher in dark chocolate than milk chocolate. Caffeine is contained in 70% of soft drinks, and widely used in pharmaceuticals for headaches, fatigue, dieting, pain relief, allergies, and cold medicine.
Interestingly, coffee growers are working feverishly on breeding coffee plants with reduced levels of caffeine. This challenge is more difficult than imagined, as caffeine is a natural insecticide and non-caffeinated varieties rely on more bitter compounds to deter pests. Even small amounts of caffeine can kill animals, including dogs.
Concluding recommendataions
In light of this research, I believe that healthy individuals can still benefit from the antioxidants in naturally decaffeinated coffee and avoid problems associated with addiction, sleep quality, and dangerous cortisol imbalances associated with its caffeinated counterpart.
In fact, a study showed that decaffeinated coffee associated with a reduction in inflammatory markers in healthy women, whereas only caffeinated coffee showed similar benefits in women with diabetes. Considering the French study, I would also recommend consuming decaffeinated coffee without milk at lunchtime unless one is concerned about absorbing more iron. Coffee and tea contain tannins that inhibit absorption of iron.
While decaffeination has typically involved harmful chemicals to remove caffeine, greener methods are gaining popularity for both coffee and tea products. Water or carbon dioxide can be used to create a safer product like Cafe Altura’s Dark Roast Decaf or Bigelow’s decaffeinated green tea.
Caffeine requires a certain enzyme to metabolize in the body, and that enzyme interacts with a wide range of drugs, including the popular synthetic thyroid drug levothyroxine. It is important to check with your doctor before consuming caffeine while taking any drugs or supplements to ensure safety.
Studies suggest that pregnant women should limit caffeine to less than 300 mg/day (3 cups of coffee). Generally, children should limit caffeine to less than 2.5 mg per kg of body weight per day. Sensitivities will vary between individuals and genetic susceptibility, and I recommend an overly cautious approach when it comes to fetal and child nutrition.
To improve the risk of developing certain diseases where caffeine has shown improvement, I recommend changing nutrition and lifestyle first. We do not yet understand the full effects of using addictive drugs to treat disease.
As with any nutritional advice, it is important to consider all physical and mental symptoms, medical history, current diet and lifestyle, family support, and spiritual resources before making major changes. In Ayurvedic medicine, caffeine is a stimulant that can aggravate the three doshas in different ways. In Chinese medicine, high consumption of caffeine can lead to imbalances in the spleen and kidney organ systems. The adrenal glands become exhausted and lead us into a vicious cycle of fatigue and overstimulation. In Western medicine, adrenal function can be measured by both urinary and salivary cortisol levels before diagnosis. Most health practitioners with herbal or naturopathic approaches can help order tests to determine the extent of the problem.
Remember that we lose ourselves and our true health when food or beverages control us. Doctors may avoid taking a stand on caffeine in the face of contradictory research and overwhelming pressure of its popularity. Be honest about your diet and symptoms with your health practitioner, and demand details and thoroughness when discussing disease prevention. Enjoy nutrition and be your healthy self!
Webs produced from caffeinated spiders. Photo courtesy NASA.
-Shari Cheves
Update: March 20, 2013
New research indicates that the preparation of coffee may dramatically impact the health benefits. A study compared diets of Greek Ikarians – who appear to live longer than other Europeans – and found that over 87% in the study drank boiled Greek coffee. Furthermore, this type of coffee drinking was associated with improved blood vessel function. Greek coffee, also known as Turkish coffee, is a method of preparing coffee where ultra-fine ground coffee is boiled and served where grounds are allowed to settle. Greek coffee has only a moderate amount of caffeine and leaves the boiled grounds at the bottom of the drinking cup.
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