En español | Whipping up a cool, creamy smoothie in your trusty blender — remember when we used to do that way back in the good ol' days, like the 1990s?

Lately, though, smoothies are being passed over for the latest beverage craze — juices and juice fasts. The idea is to drink nothing but juice extracted from fresh fruit and vegetable juice for several days to "cleanse" your digestive system and maybe drop a few pounds in the process.

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Both juicing and blending can be an effective way of getting more fruits and veggies into your diets. — Shutterstock

Celebs, such as Gwyneth Paltrow, are touting them. Even the 70-year-old food critic for Vogue magazine, Jeffrey Steingarten, tried an eight-day cleanse to see whether it could help him recover from an intestinal bug.

Writing about his experience in the May issue of the magazine, he admitted he thought about food "every few minutes — nearly all day." He also found it hard to focus, to write or to even stand up by the eighth day.

Sound like fun? OK, that's the extreme.

But is drinking freshly extracted juice really better for you than our old standby, the smoothie?

The answer, as with everything else, is — it depends.

Here's the funny thing: This seemingly new fad is just the latest rendition of an 80-year-old idea.

Recurring mania

The whole concept of extracting nutrient-packed juice from fruits and veggies to keep us looking young and feeling healthy dates back, not to the early 2000s, but to the 1930s, when doctor and raw food proponent Norman Walker came up with the hydraulic Norman Juicing Press.

That was followed in the 1950s by the first modern juicer — the Champion Juicer. Still sold today, it's a hefty gadget, one that Ohio caterer Scott Groth, who blogs for The Chubby Cook, says "is heavy enough to put in the back of your pickup truck in winter to avoid sliding off the road."

Then in the 1970s, everyone's favorite fitness fanatic, Jack LaLanne, sparked another juicing mania with his Jack LaLanne Power Juicer, which he pitched relentlessly on TV.

Why does juicing keep resurfacing?

One major reason undoubtedly is that anything that helps us eat more fruits and vegetables is a good thing, especially for older Americans. Studies have shown these foods help improve heart health and reduce the risk of cancer and dementia.

And, by all accounts, we need a little encouragement to eat our veggies. In 2010, the government reported that barely a third of Americans eat two servings of fruit daily and only about a quarter of us eat three servings a day of vegetables — although older Americans do a much better job at it than do younger ones.

Next: Focus on fiber. »