Drink to Your Health

"To your health" is a toast that is inappropriate with much of what Americans imbibe.

A long list of foodstuffs have been blamed for the nation's increasingly widespread weight and health problems-all fats, saturated fats, trans fats, and carbohydrates. Now the spotlight has been turned not on what Americans eat, but on what they drink. What patients drink, it turns out, often plays a very significant role in their risk of weight gain and diabetes.

Over the approximately 20-year period during which rates of overweight and obesity in the United States have steadily risen, the average American's daily energy intake has increased by 150 to 300 kcal. Half of those extra calories have come from calorically sweetened beverages-soft drinks and sweetened fruit drinks. Moreover, the percentage of energy obtained by drinking calorically sweetened beverages has increased 150% over the past 30 years, from 2.8% in 1977 to 7.0% today.¹

A growing awareness of the role of beverage consumption patterns in the nation's twin epidemics of obesity and diabetes led to the formation of the Beverage Guidance Panel.¹ The panel recently published its first set of guidelines-the Beverage Guidance System. The new guidelines are designed to provide recommended minimum and maximum daily quantities for 6 drink categories and to help educate the public about the beneficial and adverse health effects of various beverages.

WHAT TO DRINK-AND HOW MUCH

The Beverage Guidance System classifies beverages on the basis of their contribution to energy intake, essential nutrients, beneficial health effects, and adverse health effects. The 6 classes, in order of most preferred to least preferred, are:

• Level 1-water.

• Level 2-unsweetened coffee and tea.

• Level 3-low-fat and nonfat milk and soy beverages.

• Level 4-noncalorically sweetened beverages (eg, diet sodas and other diet drinks).

• Level 5-caloric beverages with some nutrients (including 100% fruit and vegetable juices, sports drinks, and alcoholic beverages).

• Level 6-calorically sweetened beverages (sodas, fruit drinks, and other beverages sweetened with sugar or high-fructose corn syrup).

The panel recommends that adults fulfill most of their daily fluid needs with beverages from the lowest levels, such that no more than 14%-and ideally just 10%-of the daily caloric intake is accounted for by beverages. The Figure shows a more detailed breakdown of recommended intake ranges for the various types of beverages.

KEY POINTS FROM THE GUIDELINES

In addition to providing recommended daily minimum and maximum amounts for the different classes of beverages, the Beverage Guidance System also summarizes the latest research on the health effects-both positive and negative-of various types of beverages.

Water. The adverse effects of acute dehydration are well established. The effects of chronic dehydration have not been well studied; however, an increased risk of bladder cancer is one known effect. Improving hydration has been shown to be associated with reduced kidney stone formation.

Caffeine-containing beverages. There is substantial evidence that moderate caffeine intake (up to 400 mg per day-the equivalent of 4 cups of coffee, 8 cups of tea, or 9 or 10 cans of cola) does not increase risk of heart disease, osteoporosis, or hypercholesterolemia in adults. Also, although caffeine is a mild diuretic, persons may consume up to about 500 mg per day without experiencing dehydration or chronic water imbalance. However, caffeine intakes of more than 300 mg per day by pregnant women have been associated with an increased risk of miscarriage and low birth weight. It is not yet clear whether caffeine has adverse effects in children.

Coffee. Coffee drinking has not been found to increase heart disease risk significantly. However, consumption of boiled, unfiltered coffee raises plasma total and low-density lipoprotein cholesterol levels. This effect is caused by 2 substances in roasted coffee beans (cafestol and kahweol) that are extracted by brewing in hot water. (Because paper filters trap cafestol and kahweol, filtered coffee does not have this effect.) Also, both filtered and unfiltered coffee increase plasma homocysteine levels.

Tea. There is not yet firm evidence that tea consumption lowers cancer risk in humans. However, theanine, an amino acid found in tea, has been shown to enhance innate immunity. The evidence also suggests that tea consumption (4 to 5 cups of black tea per day) improves endothelium-dependent vasodilation, and that 3 or more cups per day may modestly reduce risk of myocardial infarction.

Low-fat and nonfat milk. Milk remains an important element in the diets of children and adolescents. It is an excellent source of calcium, vitamin D, high-quality protein, and other essential nutrients (magnesium, potassium, zinc, iron, vitamin A, riboflavin, and folate). High levels of milk consumption by men are associated with an increased risk of prostate cancer.

100% Fruit and vegetable juices. The panel encourages the consumption of whole fruits and vegetables, rather than juices, because of their greater satiating properties. The US Dietary Guidelines Committee has recommended that no more than one third of a person's daily fruit intake be in the form of juices. Also, vegetable juices usually contain substantial amounts of added sodium.

Sports drinks. These beverages contain small amounts of sodium, chloride, and potassium, and 50% to 90% of the calories in comparable calorically sweetened soft drinks. The panel recommends that persons who are not endurance athletes consume sports drinks sparingly.

Alcoholic beverages. Moderate alcohol consumption (a maximum of 1 drink per day for women and 2 drinks per day for men) is associated with a reduced risk of cardiovascular disease, type 2 diabetes, and gallstones. These benefits appear to be associated with alcohol itself, rather than with flavonoids or other elements in wine or dark beer. However, even modest alcohol consumption by women is associated with increased risks of birth defects and breast cancer. Thus, women who are pregnant should not consume alcoholic beverages, and all women who drink alcohol should consume 400 µg per day of folate to help offset the alcohol-induced mechanism that increases breast cancer risk. Heavy alcohol consumption is associated with a number of illnesses and conditions, including cirrhosis, hypertension, hemorrhagic stroke, atrial fibrillation, cardiomyopathy, dementia, and several kinds of cancer.

Diet drinks. The noncaloric sweeteners used in these beverages have been approved by the FDA and are considered safe. However, evidence is emerging that suggests that the marked sweetness of diet sodas and other diet drinks may condition persons who drink them to strongly prefer sweetness in their food and drink generally.

Calorically sweetened sodas and fruit drinks. These beverages have contributed to the obesity epidemic because they do not readily produce feelings of satiety and thus are poorly compensated for with subsequent cutbacks on energy intake; the result is a net increase in calories consumed. Evidence also links consumption of soft drinks and fruit drinks with an increased risk of type 2 diabetes.

References:

REFERENCE:

1.

Popkin BM, Armstrong LE, Bray GM, et al. A new proposed guidance system for beverage consumption in the United States.

Am J Clin Nutr

. 2006;83:529-542.