Sizing Up Smoothies

How healthy are these health drinks, really? Find out what makes a smoothie worth drinking — and what might make some smoothies worth rethinking.

green smoothie

Smoothies are hard to resist: They’re creamy and delicious and have seductive names like “Razzmatazz” and “Berry Lime Sublime.” Plus, they’re everywhere – on the grocery-store shelves, at to-go counters, at special juice and smoothie bars in well-traveled locations – even at the airport. Full of health-and-energy-boosting goodies, smoothies are touted as an ideal snack choice for the health conscious.

Thanks to smart marketing and a genuine desire on the part of the American public to eat healthier, smoothies have become a bigtime operation, with sales topping $1 billion a year, according to Food Management magazine. They have carved out a unique niche in the health and fitness category by presenting themselves as a terrific post-workout snack, a healthy alternative to other forms of fast food and an easy way to help get some of your recommended daily servings of fresh produce.

On the surface, all this may be true. Many smoothies are made with whole fruits, fresh fruit juices, healthy nuts and low-fat, cultured yogurts. Some offer the addition of protein powders, super-foods and other supplements – including vitamins, minerals, herbs and amino acids – that promise to help augment nutrition, burn fat, build immunity, battle stress and reduce fatigue.

Smoothies offer a lot in a nice, portable package. Look under the lid, though, and you may find some things you don’t expect, including up to a whopping 500 calories a serving – almost a quarter of the average person’s recommended daily intake. You might also find giant supplies of syrups and sugars (simple carbs) that can spike blood glucose; artificial sweeteners, flavors and preservatives with questionable health profiles; pesticides and herbicides from chemically farmed produce; and commercial bases of frozen yogurt, sherbet and ice cream that turn smoothies into little more than cleverly concealed shakes. And what about those supplement powders and “boosts” that many vendors add? They generally promise far more than they can realistically deliver and, in some cases, may even interfere with medications.

Liquid Sugar

Perhaps the greatest concerns surrounding smoothies are their high calorie and sugar counts.

“Some smoothies, specifically grocery-store brands, add a lot of extra sugars,” says Cherie Calbom, MS, a clinical nutritionist and author of The Ultimate Smoothie Book (Warner Books, 2001). “And most of them use pasteurized juices that have been heated, killing many nutrients. What’s left is primarily sugar and water.”

The worst juice-bar offenders are generally those made from frozen yogurt and sherbet bases, many of which contain high-fructose corn syrup or sugar as a leading ingredient, and which may also contain chemical stabilizers and texturizers. Smoothies made mostly from all-natural fruit juices, although healthy in that they don’t contain any additives, may still be high in sugar.

It’s the high sugar that makes smoothies so appealingly sweet, of course, but to your metabolism, those same sugars can make a smoothie largely indistinguishable from a soda or milk shake – particularly if you choose one of those vat-sized smoothies currently selling faster than Frappucinos. Such big helpings of sugar send blood glucose levels spiking, causing the pancreas to produce a flood of insulin in response. Because there’s not enough fiber, protein or fat in most smoothies to slow down the digestive process, soon after the sugar spike comes the crash, which can leave you craving more sugar.

Not only is this cycle a setup for weight gain and insulin resistance (also known as metabolic syndrome, a precursor to type 2 diabetes), it can also do a number on your appetite just a couple of hours later. “In the end,” says Jana Klauer, MD, a New York physician who specializes in weight reduction and nutrition, “you might feel hungrier than you were before drinking the smoothie.”

Boost Busting

OK, so they present a bit of a caloric quagmire. But at least they’re nutritious – aren’t they? Here, too, experts say, it pays to adjust your expectations. In general, you’re better off with most smoothies than with, say, a bag of chips. But they’re typically nowhere near as healthy or sustaining as a well-balanced meal. And unless they are based mostly on fresh, whole-food ingredients, they may contain fewer nutrients (and far more calories) than a decent nutritional bar.

Smoothies can play a supporting role in a healthy diet and lifestyle – particularly as an on-the-go breakfast, afternoon snack or post-workout replenisher – but they are not ideal replacements for most regular meals. You also have to separate the supposed health benefits from the hype, particularly when it comes to nutritional claims arising from nonfood sources.

Don’t be fooled, for example, by claims suggesting a smoothie can offer a day’s worth of certain essential minerals in just one serving – especially calcium. According to Klauer, this is just plain unrealistic. “You can only absorb a certain amount of a mineral like calcium in one sitting,” she says, “so it’s misleading to advertise a drink as capable of providing 110 percent of the recommended daily allowance.”

Many retail chains advertise “power boosts” or “energy boosts” based on herbal ingredients that have not been evaluated by the Food and Drug Administration or whose claims are widely disputed, says Klauer. Chromium picolinate, a popular diet supplement, has long been credited with building muscle tissue, enhancing athletic performance and aiding in weight loss. But Klauer says that, except in chromium-deficient individuals, clinical results are still inconclusive. As a result, she believes many chromium-boost claims are misleading and overstated.

Other much-touted smoothie additions have received similar so-so reviews from scientists. For example, Jamba Juice, a national chain, claims that its “energy-boost” smoothie contains a “potent combination of ginseng and ginkgo biloba, rhodiola and guarana that help fight fatigue, increase stamina and boost energy.” But the research is still sketchy. While there have been some studies to support these and other herbs’ claims of therapeutic benefits, for the most part, Western medicine has yet to sign off on them with confidence.

Possible side effects pose an additional concern. Although some research has shown that ginkgo biloba might slow the progression of dementia (chronic loss of one’s mental capacity) by increasing blood flow to the brain and possibly reducing mental fatigue, the herb may also trigger headaches and gastrointestinal problems in some people. Guarana increases energy levels because it’s a form of caffeine, but like all caffeine it may also cause side effects, such as restlessness, nervousness and insomnia.

The other problem with herbs in retail smoothies is that you can’t be sure of their quality. According to a recent study by the Medical College of Wisconsin (American Journal of Obstetrics and Gynecology, May 2003), ginseng is often impure: All varieties of ginseng extract are extremely expensive, which means that the cheaper forms often sold in retail health-food products are most likely mixed with other herbs.

Since many herbs are forms of medicine, it’s smart to consult your health professional before ingesting them, particularly if you’re taking any prescription medications – especially antidepressants and certain heart medications, with which they may react negatively.

Buyer Beware

So is it time to give smoothies the boot? Not necessarily. The solution is to investigate and select your smoothies carefully, or to make them at home so you can control both serving size and quality while reducing cost. A few tips …

Whether you are making or buying, choose organic produce and ingredients whenever possible, both for superior taste and higher nutritional content. A study published in the Journal of Applied Nutrition (Vol. 45, No. 1, 1993) found that organically grown produce can contain over 90 percent more of the nutritional elements found in similar commercial food.

If you’re buying packaged smoothies, read the ingredient and nutrition labels carefully. Check the number of servings in each package and avoid products with lots of added sugars, syrups, hydrogenated oils and additives. Needless to say, you should probably also look askance at smoothies in flavors like “cheesecake,” “caramel” and “banana split.”

When frequenting a particular retail chain, ask to see the ingredient and nutrition labels for any commercially prepared yogurt, sherbet and flavor-base mixes. Choose plain, cultured yogurts when possible. Apple-juice bases might be somewhat less caloric but are generally still high in sugar and, unless they’re organic, may also contain unhealthy chemical residues.

If you decide to go the home route, start with a good, whole-foods-based recipe: 1/2 cup frozen berries (a combination of blueberries, raspberries and strawberries is delicious), 1/2 a banana, and 1/2 cup cold purified water or three to four ice cubes made from purified water (depending on how icy you like your drinks). From there, for protein and texture, you can add a 1/2 cup of natural, cultured yogurt or soymilk (choose the fat and sugar content that suits you) and a handful of nuts or seeds; see “Smart Smoothies” (page 26) for more suggestions.

Finally, whatever you put in, keep in mind that because smoothies go down so easily, it’s easy to “overdrink” them. So, particularly if you’re watching your weight, it’s a good idea to track how much nutrition and how many calories you’re putting into the blender. Also keep in mind that your smoothie doesn’t need to be milk-shake sweet to taste good. Experiment with getting additional flavors by adding and rebalancing other ingredients.

Above all, avoid the temptation to supersize – both at home and at the store. No matter how healthy they are, smoothies ingested in “Big-Gulp” servings tend to deliver big-gut results.

Michelle Gagnon is a freelance health and fitness writer based in California.

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