Does your smoothie need a boost?

If you've stood in line at a Jamba Juice, Smoothie King, or Elixir shop, or ordered a pumped-up smoothie at a local juice bar, health-food store, or gym, you've experienced one of America's newest and fastest-growing health trends -- wellness drinks, also known as "functional beverages."

These blended drinks are made from combinations of juice, fruit, milk, frozen yogurt, sorbet, and -- this is the key -- "boosts" of herbs, vitamins, fiber, and other substances.

They often come with promises of increased energy, better mood, sharpened memory, stress relief, weight control, super immunity, and detoxification, or make other far-reaching health claims. That's a lot for a smoothie to live up to.

The problem with boosting

Boosts (also called supplements or enhancers) include aloe, bee pollen, echinacea, ginkgo, St. John's wort, chromium, green tea extract, and carnitine, to name a few. Though you don't have to order a boost, most people do. But how much of these ingredients are you actually getting? A lot, a little, or do you just not know? And what would be the "right" amount anyway, assuming you really need them in the first place?

Some companies provide ingredient information (at the store or on the Internet). For example, the Jamba Juice brochure describes boosts with eight grams of fiber (a good amount), 100 percent of the Daily Value for 20 vitamins and minerals (basically, a liquid multi that you may not need), and 1,000 percent for vitamin C (equal to a 600-milligram pill).

More often, the information is vague ("weight management botanicals" are listed, for example, without specifying what they are) or not available at all. In all likelihood, the boosts probably contain too little of an herb or other substance for it to have any effect, good or bad. But who knows?

An occasional boost of glucosamine, for instance, won't hurt you, but it probably won't help your arthritic knees, either. And there's no guarantee that the ginseng (a costly herb) is even true ginseng. On the other hand, the safety of some substances is unknown. Energy and performance-boosting drinks most likely contain caffeine and other stimulants.

The use of dietary supplements in beverages or elsewhere is largely unregulated, and so far no government agency has cracked down on any health claims made by juice bars. You shouldn't trust dietary advice from the person behind the counter. To be safe, skip the boosts, especially if you are pregnant, have an auto-immune condition, or are on any medications.

Next time you're at the juice bar ...

Other things to consider when you belly up to the juice bar:

On the positive side, smoothies made with mangoes, berries, melons, beets, carrots, and other colorful produce are packed with vitamins, minerals, phytochemicals, and fiber (when made with the whole fruit) and count toward your daily fruit and vegetable intake -- anywhere from two to five servings, depending on the drink size.

Smoothies that contain yogurt or milk provide protein and calcium. Soy milk is another healthful option. But watch out for local establishments that use juice "drink" (that is, juices that are diluted with water and have added sugar).

The downside: Most smoothies are loaded with calories. For example, the 24-ounce "Razzmatazz" from Jamba Juice contains 480 calories, the Peenya Kowlada, 690. And those aren't even the largest sizes. That's more calories than some people should consume in an entire meal, let alone in addition to a meal. There's no reason anyone should be drinking this much of any beverage -- even water -- at one sitting.

Order the smallest size, or split one with a friend or two. Watch out for higher-calorie extras, like coconut and peanut butter. Some juice bars offer lower-calorie smoothies made with the sugar substitute Splenda.

Bottled "functional" smoothies, such as Fresh Samantha, Odwalla, and Naked Food-Juice, are also high in calories. There may be more than one "serving" in a bottle, so if you drink it all, be sure to multiply the calories listed on the label accordingly.

Fresh-made smoothies are not cheap -- about $4 to $7. They cost less if you make them yourself.

How to make smoothies at home

In a blender, combine one or more fruits (fresh or frozen), one liquid, one sweetener (optional), and one spice from the following list. Add six ice cubes and blend until smooth and frothy. These smoothies average about 230 calories.

Fruits: Mango (1 cup, sliced), banana (1 large, sliced), strawberries (1 cup, halved), peaches (1 cup, cubed), pineapple (1 cup, cubed) -- you can select any favorite fruit or combine fruits.

Liquids: Yogurt, plain low fat (1 cup); buttermilk (1 cup); milk, low fat or nonfat (1 cup); soy milk, unflavored (1 cup); tofu, soft silken (1/2 cup).

Sweeteners: Honey (1 tablespoon), sugar (2 teaspoons), maple syrup (1 tablespoon), or sugar substitute.

Spices: Cinnamon (1/2 teaspoon), nutmeg (1/4 teaspoon), ground ginger (1/2 teaspoon).