Green tea comes from the Camellia sinensis plant and is rich in polyphenols — micronutrients that are packed with antioxidants and potential health benefits. Since green tea contains caffeine, however, you may experience some uncomfortable side effects like irregular bowel movements.
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Benefits of Green Tea
Tea is one of the most popular beverages consumed worldwide, however, among all types, the most significant effects on human health have been observed with the consumption of green tea. The process in which green tea is made more effectively preserves natural polyphenols which confer health-promoting properties. Tea is rich in antioxidant, antimutagenic and anticarcinogenic effects, which could protect humans against the risk of cancer and environmental agents.
In a study published in the March 2015 issue of the Journal of Translational Medicine, researchers found that green tea catechins serve in a preventive role against obesity, hypercholesterolemia and hyperglycemia.
Based on diets, four studies were conducted on rats in which functional drinks were prepared by adding catechins and epigallocatechin gallate and compared with control. Rats that were provided functional drinks resulted in significant body-weight reduction, reduced cholesterol and LDL, and decreased serum glucose and insulin levels.
Effects of Caffeine
Caffeine is a bitter substance that occurs naturally in more than 60 plants, including tea leaves. Although tea doesn't have as much caffeine as coffee, it still contains a significant amount, ranging from 14 to 60 milligrams per eight ounce cup of tea. According to MedlinePlus, within one hour of eating or drinking caffeine, it reaches its peak level in your blood and you may continue to feel the effects of it for four to six hours.
Caffeine has many effects on your body's metabolism, including stimulating your central nervous system, increasing acid release in your stomach and increasing blood pressure. Since caffeine is a diuretic, it draws fluid from your body and excretes it as urine. This process dehydrates your body, which forces the colon to pull extra water from the stool, which may leave you with some uncomfortable bowel movements like diarrhea or unusual stool texture.
Read more: How Many Cups of Coffee a Day Can You Drink?
Caffeinated drinks such as green tea can help with constipation because they stimulate bile production, which aids in the breaking down and passing of stool through the colon.
Healthy Serving Tips
Unusual bowel movements aren't the only effect of caffeine — many users also experienced anxiety, insomnia and high blood pressure. If you enjoy tea on a daily basis, you may want to consider transitioning from caffeinated to decaffeinated.
However, decaffeinated tea is different from caffeine-free tea. The decaffeination process leaves a minimal amount of caffeine in the leaf. By law, tea labeled as "decaffeinated" must have less than 2.5 percent of its original caffeine level — usually measuring out to 2 milligrams per cup.
If you do want to stick to caffeinated tea, don't use the tea as your only source of hydration. According to the University of Michigan Health System, for every cup of caffeinated fluid, you should drink two cups of decaffeinated fluid. In addition, do not rely on the foods that you eat for your fluids — the water in your food should be considered bonus fluids.
- NCBI: Journal of Nutrition: "A Review of the Health Effects of Green Tea Catechins in In Vivo Animal Models"
- NCBI: Chinese Medicine: "Beneficial Effects of Green Tea: A Literature Review"
- University of Michigan Health System: "Bowel Function Anatomy"
- MedlinePlus: "Caffeine"
- Center for Science in the Public Interest: "Want to Know How Much Caffeine Is in Tea?"
- NCBI: Oxidative Medicine and Cellular Longevity: "Plant Polyphenols as Dietary Antioxidants in Human Health and Disease"
- Providence Health Plan: "Constipated? You Don’t Have to Be"
- U.S. National Library of Medicine: Genetics Home Reference: "Hypercholesterolemia"
- Mayo Clinic: "Hyperglycemia in Diabetes"
- Journal of Translational Medicine: "Preventive Role of Green Tea Catechins From Obesity and Related Disorders Especially Hypercholesterolemia and Hyperglycemia"