Healthy drinks: water, tea and coffee

Healthy drinks. Beverage guidelines were developed by Drs. Barry Popkin, Lawrence Armstrong, and others. These guidelines were published in The American Journal of Clinical Nutrition (‘A new proposed guidance system for beverage consumption in the United States’, Am. J. Clin. Nutr. 83: 529-42, 2006).

Water

Water intake is necessary for normal metabolism and physiological functioning, and provides essential minerals such as calcium, magnesium and fluoride. Drinking water is very safe and has no adverse effects on health. Acute dehydration results in impaired perception, moodiness, poor thermoregulation, reduced cardiovascular function and reduced capacity for physical work. In general, excessive water intake in healthy people with normally functioning kidneys has no adverse health effects because the kidneys can produce a large amount of urine in a relatively short period of time to correct a disturbance.

Tea / Camellia sinensis

Black, green and oolong teas are the most consumed worldwide. Tea provides many flavonoids and antioxidants, and some micronutrients, such as fluoride. There is clear evidence that tea protects against chemically induced cancer in laboratory animals. But it remains unclear whether tea consumption also reduces the risk of cancer in humans. Tea also provides amino acids, especially L-theanine, which is said to provide a relaxed yet alert state of mind, and improve immunity. Tea consumption may also increase bone density, reduce tooth decay and cavities, and reduce the formation of kidney stones. Epidemiological studies indicate that daily intake of at least three cups of tea may be associated with a modest reduction in the risk of myocardial infarctions (heart attacks).
Adding sugar, milk or cream to tea and coffee is less desirable due to the increase in energy and fat content.

Coffee / Coffea arabica

Regarding coffee intake, several studies have shown a reduced risk of type 2 diabetes. High coffee intake has been associated with significant reductions in the risk of colorectal cancer in many studies, while other studies showed no significant association. Coffee and caffeine consumption has been consistently associated with a significant reduction in the risk of Parkinson’s disease in men, but not women, which may be attributable to the influence of estrogen. Boiled unfiltered coffee, unlike normal filtered coffee, has been shown to have a negative cardiovascular effect due to increased serum cholesterol levels.
Coffee contains more caffeine than tea. Although caffeine has a mild diuretic effect, human studies indicate that consuming caffeine up to approximately 500 milligrams per day does not cause dehydration. The fluid in caffeinated drinks compensates for the acute diuretic effect. So far, evidence suggests that modest caffeine intake of up to 400 milligrams per day is not associated with an increased risk of heart disease, hypertension, osteoporosis or high cholesterol. Pregnancy and aging can affect sensitivity to caffeine. Pregnant women are often advised to limit caffeine intake, as consumption of more than 300 milligrams per day has been linked to an increased risk of miscarriage or low birth weight.
Some studies indicate that the effect of caffeine is smaller with low and high intake, but greater with moderate intake. This relationship has been reported for time required to perform tasks, reaction time, alertness, information processing, and moods; however, this relationship does not appear to hold for all physiological and psychological responses.

How much of each drink should you drink?

Most adults with an energy requirement of 2200 calories should drink about 3 liters of fluid per day. No more than 10 percent of the daily total calorie intake may come from beverages. Based on this, we generally recommend the following daily amounts of the different drinks:

  • Water, 600-1500 cc (but can amount to the entire daily fluid intake of approximately 3000 cc)
  • Tea and coffee (unsweetened, with little or no milk or cream), 0-1200 cc
  • Semi-skimmed or skimmed milk and soy drinks, 0-480 cc
  • Non-calorically sweetened drinks, 0-960 cc
  • Caloric drinks with nutrients: 100% fruit or vegetable juices, 0-240 cc; whole milk, 0 cc; sports drinks, 0-240 cc, alcoholic drinks, 0-1 glass for women and 0-2 glasses for men
  • Calorically sweetened drinks, 0-240 cc
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