The Health Benefit of The Second Cup of Coffee
Whether you’re a Starbuck’s fan or a Dunkin’ donuts coffee addict, a new study published in the medical journal Circulation authored by Dr. Ming Ding, of the Harvard School of Public Health in Boston, Massachusetts will interest you. The long term study has shown that drinking moderate amounts of coffee may not be a bad idea. Researchers followed more than 200,000 doctors and nurses for up to 30 years has found that people who drank three to five cups of coffee daily had a 15 percent lower risk of dying prematurely from heart disease, stroke, diabetes, neurological diseases such as Parkinson’s, and suicide. Cancer was not a disease process found to have an improved life expectancy. 
Why might coffee help?
Coffee contains certain molecules such as chlorogenic acid, lignans, quinides, trigonelline, and magnesium that may explain the findings. These components have been found to reduce insulin resistance and systematic inflammation, both of which are factors in type 1 and type 2 diabetes. Chlorogenic acid helps reduce glucose absorption in the intestine and reduces liver glucose. In addition, chloragenic acid reduces oxidative stress which has been linked to inflammation and many disease processes including cardiovascular disease.  
Lignans are polyphenols found in plants. When consumed, lignan precursors are converted to the enterolignans, enterodiol and enterolactone, by bacteria that normally colonize the human intestine they can mimic some of the effects of estrogens, their plant-derived precursors are classified as phytoestrogens. While cancer life expectancy was not increased, scientists are interested in the tissue-selective activities of phytoestrogens because anti-estrogenic effects in reproductive tissue could help reduce the risk of hormone-associated cancers (breast, uterine, ovarian, and prostate), while estrogenic effects in bone could help maintain bone density. The enterolignans, enterodiol and enterolactone, are known to have weak estrogenic activity. Diets rich in foods containing lignans have been consistently associated with reductions in risk of cardiovascular disease. 
Independent studies show quinides in roasted coffee enhance the action of insulin in rats. 
Trigonelline contributes to the bitterness of coffee and studies have shown this substance has the ability to inhibit cancer cells and improve memory. A byproduct of the demethylation of trigonelline is niacin, which is needed for proper circulation, function of the nervous system and helps in regulation of carbohydrates, fats, and proteins.  
Magnesium is a vital catalyst for enzyme activity and energy production and also protects the arterial linings from the destructive effects of stress as well as assisting in the uptake of calcium and potassium. With Vitamin B-6 Magnesium helps prevent and dissolve calcium phosphate kidney stones. A deficiency can be manifested in symptoms of confusion, insomnia, irritability, poor digestion, rapid heart rate, seizures and symptoms of diabetes. Magnesium is helpful in the prevention of cardiovascular disease, osteoporosis, and certain forms of cancer and may reduce cholesterol levels.
Studies have also shown coffee consumption to be associated with a lower risk of Parkinson’s diseases (PD).
Three published cohort studies have shown an inverse association between coffee consumption and risk of suicide however, one study showed a J-shaped association where heavy coffee consumption was associated with a higher risk of suicide. Our study had shown an association of both caffeinated and decaffeinated coffee consumption with risk of suicide in both the whole population and never smokers, indicating that coffee consumption might have antidepressant effects.
Dr. Ding reported, “Researchers analyzed health data gathered from participants in three large ongoing studies: 74,890 women in the Nurses’ Health Study; 93,054 women in the Nurses’ Health Study 2; and 40,557 men in the Health Professionals Follow-up Study. Coffee drinking was assessed using validated food questionnaires every four years over about 30 years. During the study period, 19,524 women and 12,432 men died from a range of causes.”