Coffee and health
COMPOUNDS IN COFFEE THAT CAN AFFECT HEALTH
COFFEE
Caffeine occurs naturally in coffee beans. Some physiological effects associated with caffeine administration include stimulation of the central nervous system, acute increase in blood pressure, increased metabolic rate and diuresis. Caffeine is rapidly and almost completely absorbed in the stomach and small intestine and distributed to all tissues, including the brain.
CAFESTOL AND KAHWEOL
Coffee consumption has been associated with higher cholesterol concentrations in some observational studies. Clearly, filter coffee, which contains the least cafestol and thus has the least effect on cholesterol, is the best of all coffee preparation methods.
On the other hand, coffee brewed in a pot was the worst. Thesecond worst preparation is the classic Czech turk. The long steeping process eliminates substances that have no place in coffee, one of which is cafestol. If you still love turk, we recommend the French press.
The cholesterol-raising factors that were first isolated in coffee oil were later identified as diterpenes, cafestol and kahweol. These diterpenes are extracted from ground coffee during brewing, but are usually removed from the coffee by paper filters.
MICROCROTE
A number ofmicronutrientsare found in coffee, including magnesium, potassium, niacin and vitamin E, among others. According to the USDA Nutrient Database, 240 ml of brewed coffee contains 7 mg of magnesium and 30 ml of espresso contains 24 mg of magnesium. Thus, one cup of coffee could contribute 1-5% of an adult male's recommended daily intake of magnesium (420 mg/d).
POSSIBLE HEALTH BENEFITS
PREVENTION OF DIABETES MELLITUS 2. TYPE
Epidemiological studies have found a significant association between the risk of type 2 diabetes mellitus (DM) and coffee intake. This study found that the risk of developing type 2 DM was 50% lower in those who consumed at least 7 cups of coffee daily compared to those who drank 2 or fewer cups of coffee.
The two largest prospective studies have examined the relationship between coffee consumption and type 2 DM. Men who drank at least 6 cups of coffee per day had a 54% lower risk of developing type 2 DM than men who did not drink coffee. Women who drank at least 6 cups of coffee a day had a 29% lower risk than women who did not drink coffee at all.
PREVENTION OF PARKINSON'S DISEASE
Overall, the results of the case studies suggest that coffee and caffeine intake are inversely associated with a lower risk of Parkinson's disease. A study of more than 8,000 men found that those who did not drink coffee were 3 to 5 times more likely to develop Parkinson's disease in the next 24 to 30 years.
SUICIDE RISK
Two prospective studies in the US found significant associations between coffee consumption and suicide risk. A study of more than 128,000 men and women found that the relative risk of suicide decreased by 13% for each cup of coffee consumed per day. Similarly, a study of more than 86,000 women found that those who drank at least 2 cups of coffee per day had a 50% lower risk of suicide than those who did not drink coffee.
PREVENTING COLORECTAL CANCER
In general, coffee consumption is inversely associated with colon cancer risk in case-control studies . The two largest prospective cohort studies that have examined the relationship between coffee and colorectal cancer found that men and women who regularly consumed 2 or more cups of decaffeinated coffee daily had a 48% lowerrisk of rectal cancer than those who never consumed coffee.
LIVER INJURY, CIRRHOSIS AND HEPATOCELLULAR CARCINOMA
Liver injury due to chronic inflammation can lead to cirrhosis. In cirrhosis, fibrotic scar formation leads to progressive deterioration of liver function and other complications, including hepatocellular carcinoma. Themost common causes of cirrhosis in developed countries are excessive alcohol consumption and viral hepatitis B and C.
A study of more than 51,000 men and women found that those who consumed at least 2 cups of coffee daily had a 40% lower risk of death from cirrhosis than those who never consumed coffee. A prospective cohort study that followed more than 90,000 men and women for 10 years found that the risk of hepatocellular carcinoma decreased as coffee consumption increased. Those who consumed at least 5 cups a day had a 76% lower risk of hepatocellular carcinoma than those who never drank coffee.
POSSIBLE HEALTH RISKS
CARDIOVASCULAR DISEASE
RISK OF HEART DISEASE
Several epidemiological studies have examined the relationship between coffee consumption and the risk of coronary heart disease (CHD). Case-control studies have found that high coffee intake is associated with anincreased risk of myocardial infarction (MI). Two separate meta-analyses that combined the results of eight case-control studies found that the risk of CHD was 40-60% higher in those who consumed 5 or more cups of coffee per day compared with those who did not drink coffee.
CORONARY HEART DISEASE
The effect of coffee or caffeine consumption on people with established CHD has not yet been studied. One case-control study found that high coffee consumption, defined as more than 10 cups per day, was associated with a significant increase in the risk of sudden cardiac arrest in patients with documented coronary artery disease.
CARDIAC ARRHYTHMIAS
Clinical studies have not found coffee or caffeine intake to increase the frequency or severity of cardiac arrhythmias in healthy people, patients with CHD, or people with pre-existing ventricular ectopy. A large prospective US study that followed more than 128,000 health plan members for 7 years found no association between coffee consumption and sudden cardiac death. More recently, two prospective studies in Scandinavia found no association between coffee consumption and the risk of developing atrial fibrillation, a common supraventricular arrhythmia.
RISK OF STROKE
Few prospective cohort studies have reported associations between coffee consumption and stroke. In general, these studies have not observed significant associations between coffee consumption and stroke risk. The only exception was a study of 499 nonsmoking hypertensive men enrolled in the Honolulu Heart Study. In this high-risk population, the risk of stroke in men who consumed at least 700 ml of coffee daily was twice that of men who did not drink coffee.
HYPERTENSION
Hypertension is a recognized risk factor for CHD and stroke. Acute dietary caffeine consumption has been shown to increase blood pressure in normal and hypertensive individuals. A dose of 200 - 250 mg of caffeine has been found to be equivalent to the amount in 2 - 3 cups of coffee. increase systolic blood pressure by 3 - 14 mm Hg and increase diastolic blood pressure by 4 - 13 mg Hg.
CANCER
Numerous epidemiological studies have examined the relationship between coffee and caffeine consumption and cancer risk. In general, there is little evidence that coffee consumption increases cancer risk. Although early case studies tended to show positive associations between caffeine intake and pancreatic, bladder, and ovarian cancers, more recent and better-designed studies do not support the hypothesis that coffee consumption contributes significantly to the risk of these cancers. Recent prospective cohort studies have not observed significant associations between caffeine or coffee intake and risk of pancreatic, bladder, ovarian, breast, stomach and prostate cancer.
OSTEOPOROSIS AND HIP FRACTURE
Results of studies with controlled calcium balance in humans show that caffeine consumption leads to a small negative calcium balancein individuals with inadequate calcium intake. The negative shift in calcium balance is estimated to be about 4 to 6 mg of calcium per cup of coffee and is due to a slight reduction in calcium absorption efficiency. Most cross-sectional studies have found no association between caffeine consumption and bone mineral density (BMD).
Five studies examined the relationships between coffee and caffeine consumption and hip fracture risk. None of them found that coffee or caffeine consumption was associated with an increased risk of hip fractures. Six prospective cohort studies examined the association between caffeine consumption and hip fracture risk in women. Two studies found no association. Another study found that women who consumed at least 9 cups of coffee per day had an increased risk of hip fractures. Three prospective cohort studies found that coffee or caffeine consumption was positively associated with hip fracture risk in women.
MINERAL DEFICIENCIES
IMPAIRED IRON ABSORPTION
Polyphenols in coffee can bind non-heme iron and inhibit its intestinal absorption. Drinking 150-250 ml of coffee in a test meal was found to inhibit ironabsorption by 24-73%. To maximize iron absorption from food or iron supplements, simultaneous coffee intake should be avoided.
IMPAIRED ZINC ABSORPTION
Dietary zinc absorption inhibitors increase the risk of zinc deficiency. Zinc chelating compounds have been identified in coffee and coffee has been found to inhibit zinc bioavailability by 21-32%.
RISK GROUPS
WOMEN OF CHILDBEARING AGE
CAFFEINE AND CONCEPTION
Numerous epidemiological studies have examined the relationship between caffeineconsumption and conception rates in women who do not use contraception. Some studies have found no significant delays in conception time associated with caffeine intake. Other studies found that only high intakes of coffee or caffeine in the range of 400-800 mg/d were associated with significant delays in conception. Several of these studies have been criticized for not adequately controlling for other lifestyle factors related to fertility, such as cigarette smoking and alcohol consumption in particular.
CAFFEINE AND PREGNANCY
The results of numerous epidemiological studies that have examined the relationship between maternal coffee or caffeine intake and the risk of spontaneous abortion have been inconsistent. While some studies have observed significant associations between high caffeine intakes and the risk of spontaneous abortion, other studies have found no significant associations.
LACTATION
Caffeine is detectable in breast milk within 15 minutes of consumption and peaks approximately one hour after consumption. After consumption of caffeine by the mother, caffeine is available to infants through breast milk at less than 2 mg per 24 hours.
CHILDREN
Research on the effects of caffeine consumption in children is limited and most studies have focused on behavioural effects. A meta-analysis of nine short-term clinical trials of caffeine in children, including four in normal children and five in children with attention deficit hyperactivity disorder (ADHD), found no significant adverse effects on behaviour. In general, doses of caffeine less than 3.0 mg/kg body weight did not lead to adverse effects in children in controlled clinical trials. However,higher doses have led to some behavioural effects such as increased nervousness or anxiety and sleep disturbances.
OLDER ADULTS
Coffee is the most common source of caffeine in the elderly. There is limited evidence that older adults are more susceptible to the acute effects of caffeine to increase blood pressure. Higher plasmacaffeine concentrations could make older adults more likely to be at risk of drug interactions if they are taking one or more medications that interact with caffeine.
The results of several prospective cohort studies suggest that high caffeine intake may contribute to the risk of hip fracture, particularly in the setting of calcium and vitamin D deficiency. Overall, there is some evidence to suggest that older adults are more susceptible to some of the adverse effects of caffeine than younger adults.
SIDE EFFECTS OF CAFFEINE
ADVERSE REACTIONS
Adverse reactions include tachycardia, palpitations, insomnia, restlessness, nervousness, tremor, headache, abdominal pain, nausea, vomiting, diarrhea, and diuresis.
ACUTE TOXICITY AND OVERDOSE
Fatal or life-threatening overdoses of caffeine involve ingestion of caffeine-containing drugs. Thelethal dose is estimated at 100 - 200 mg/kg body weight. Symptoms of caffeineoverdose include agitation, delirium, seizures, dyspnoea, cardiac arrhythmias, myoclonus, nausea, vomiting, hyperglycaemia and hypokalaemia.
CAFFEINE WITHDRAWAL
Symptoms from caffeine withdrawal have been documented in a number of experimental studies. Commonly reported symptoms of caffeine withdrawal include headache, fatigue, drowsiness, irritability, difficulty concentrating, and depressed mood. In addition, nausea and myalgia may be present. Significant withdrawal symptoms have been observed at long-term intakes as low as 100 mg/day, although they are more common at higher intakes. Gradual reduction of caffeine seems likely to lead to fewer withdrawal symptoms than abrupt withdrawal.