The Coffee Controversy

By Glen Hyland, M.D.

Humans have been ingesting caffeinated plants since the Stone Age. Steeping plants containing caffeine increased the stimulatory effects. Coffee use is recorded as early as the 9th Century in Ethiopia. Merchant trade of coffee from the Middle East is recorded from the 1450’s. Coffee houses began in England in the 1650’s, though it was referred to as Arabian wine during that period. As for today’s traditional “Cup of Joe,” estimates state that as high as 90% of American adults consume coffee (1-2 cups/day), while 40% will consume 4 or more cups/day.

Of the 200 plus chemicals found in coffee, caffeine(1,3,7trimethylxanthine) is the primary reason for its consumption. Caffeine is both a central nervous system (CNS) and metabolic stimulant, affecting neurotransmitter function (adenosine, dopamine, serotonin, adrenergic, muscarinic, and nicotinic receptors) and endocrine function (ACTH, cortisol, insulin, gastric acid, epinephrine, and free fatty acid levels).

Neurologic effects of coffee are related to caffeine and antioxidants:

• increases heart rate, blood pressure, and blood flow to muscles, but decreases blood flow to skin and cerebrum •increases blood sugar and FFA levels
for aerobic and anaerobic energy production
•increases blood sugar and FFA levels for aerobic and anaerobic energy production
• increases respiration, dilates pupils
• improves alertness, wakefulness, and flexibility in acceptance of other’s opinions
• increases likelihood of tremors, anxiety, nervousness, and irritability
• increases ACTH production from pituitary which increases cortisol levels and prepares for fight or flight response
• increases epinephrine release from adrenal gland
• increases intraocular pressure (1-2 points only); induces tinnitus (ringing in the ears)
• increases risk of sleep disturbance, adding to morning fatigue and drowsiness
• possibly improves short-term memory of simple tasks, but not of complicated tasks

The Crash: cognitive clouding, fatigue, sleepiness, +/- anxiety commonly occurs 4-6 hours after ingestion of coffee, lasting 1-2 hours.

Due to the dopamine receptor effect of caffeine, incidence of Parkinsonism is lower in patients with moderate coffee intake.

There is a lower recorded incidence of dementia in patients with moderate coffee ingestion; it is believed this is due to an antioxidant effect of coffee.

If caffeine ingestion continues chronically, specifically in high amounts (>6 cups/day), adrenal fatigue may result in 1 to 2 decades and/or Insulin Resistance may develop (Syndrome X, Metabolic Syndrome).

Cardiovascular effects of caffeine are controversial: Blood pressure measured either peripherally or centrally(within ascending aorta) temporarily rises with the consumption of caffeine. Peripheral BP measurements usually correct to normal without sustained BP elevation/hypertension (HTN). Highly sensitive patients may develop HTN with sustained caffeine ingestion. Total caffeine withdrawal for 6months is usually required to correct caffeine induced HTN. Arrhythmias (irregular rate or rhythm of heart beat) can be induced by caffeine in patients with unhealthy conduction systems but are unlikely in healthy heart patients. Toxic caffeine levels (150 mg/Kg) can produce fatal arrhythmias; this would take 50 to 200 cups of coffee.

ASVD (atherosclerosis/atherosclerotic vascular disease) suggests no increased risk of heart disease among coffee users according to most studies, including Harvard (1990). Newer information shows a link between caffeine and homocysteine production. If correct, there could be a link between caffeine and ASVD, although the antioxidants in coffee could counteract the homocysteine effect.

Urologic effects of coffee are primarily caffeine related: The diuretic effect of caffeine is well known. With a continued stable level of coffee ingestion, the diuretic effect becomes balanced, and excess water loss is markedly diminished. Frequency and nocturia are commonly caused by caffeine. In patients having had prostate operations (TURP or RRP), incontinence is more common in coffee users. Minerals, including calcium, magnesium, zinc, selenium, sodium, and iron are filtered and reabsorbed by the renal tubules. Caffeine can limit the reabsorption of these minerals. Possible side effects of limited reabsorption include bone loss (osteoporosis), kidney stones, infection risk, infertility risk, hyponatremia (low sodium), hypotension, and iron deficiency/anemia. Appropriate supplementation of calcium and magnesium minimizes bone loss. Zinc and selenium supplementation can help prevent increased infection and infertility risks respectively. Iron supplementation is rarely needed unless a GI tract or GU tract blood loss is apparent.

GI tract effects of coffee are related to caffeine, antioxidants, and bean oils: Increased gastric acid secretion by parietal cells may cause heartburn, especially if a hiatal hernia is present. Senior citizens typically have a decrease in gastric acid secretion, which may be corrected by modest use of coffee. Both caffeinated and decaffeinated coffee decrease lower esophageal sphincter tone, thereby allowing reflux of gastric acid into the esophagus, producing esophagitis (inflammation of the esophagus). Patients with heartburn (dyspepsia), esophagitis, gastritis, or peptic ulcer disease should avoid coffee and other caffeinated beverages.

Bile flow is stimulated by caffeine, helping to prevent gallstones, promoting fat absorption (including fat soluble vitamins), and maintaining normal liver function (including liver detoxification).

Gastric emptying, bowel peristalsis, and rectal stool evacuation are all stimulated by both the caffeine and bean oils in coffee. Thus, excess coffee use may lead to diarrhea. Normal bowel elimination is important to help prevent colon cancer(CA).  Antioxidants in coffee may help reduce colon CA risk.

Pancreatic function related to caffeine and antioxidant effects of coffee: Studies regarding coffee (caffeine) and pancreas function suggest that Insulin Resistance can be a side effect of chronic caffeine use. Very modest use or avoidance of coffee is traditionally recommended for diabetic and metabolic syndrome patients; this helps prevent hypoglycemic episodes. However, one
study suggests a high ingestion rate of coffee (6-10 cups/day) in senior citizens (65 or older) decreases incidence of diabetes and pancreatic cancer, an antioxidant effect.

Reproductive effects of coffee related to estrogenic influence of caffeine and lack of renal tubular reabsorption of selenium: Fibrocystic breast disease, PMS symptoms, decreased sperm motility, and premature deliveries in women with history of spontaneous abortion are due to estrogenic effects of caffeine or depletion of selenium.

Coffee as a possible carcinogen (cancer inducing agent): Older epidemiologic studies have suggested that coffee is carcinogenic. Correlation between coffee use and cancer includes Bladder, NHL (Non-Hodgkin’s Lymphoma), Ovarian, Pancreatic, and Kidney. The carcinogenic agent or possible promoter chemicals are related to caffeine and similar metabolites of coffee. Caffeine appears to prevent tumor protein 53, providing the time for DNA mutation repair, thereby allowing mutated DNA to be carried forward. Consistent mutations resulting from caffeine ingestion that predictably cause specific cancers have not been shown in research. It is possible the potential carcinogenic effect of caffeine is counteracted by the antioxidants in coffee and other nutrients of a balanced diet.

Interestingly, Allen Conney of Rutgers State University of N.J. has found that the presence of caffeine in skin lotions may have a protective effect against the development of BCC(Basal Cell CA) and SCC (Squamous Cell CA) of the skin. Caffeine appears to block ultraviolet light, thereby decreasing induction of skin cancers.

Individual responses to the chemicals found in coffee are highly varied, due in majority to differences in age, detoxification by liver, use of BCP, HRT, pregnancy status, and neurotransmitter sensitivity. The amount ingested and rate of ingestion may also account for response differences. Despite the controversies of coffee ingestion side effects, 2 cups/day is safe for the vast majority
of asymptomatic coffee users.