Mankind struggles with myriad everyday dilemmas—monk straps or lace-ups? SoulCycle or Flywheel? The latest (and possibly most pressing) quandary: cold-pressed or blended juice? Because in an industry that has hit $5 billion in annual sales, opinions are divided and the science is inconclusive.

Devotees of cold-pressed (fruits and vegetables are pulverized into a fiber-free libation) point to its purity. "When you drink fresh veggie juices . . . it's like injecting goodness straight into your bloodstream," writes Jess Ainscough, a holistic-health coach. Erica Huss, cofounder of the juicing giant BluePrint, agrees: "Juice that is pressed is assimilated more quickly—you feel the energy boost almost immediately."

But blending buffs (who add water, ice, or dairy to whole produce and don't discard the pulp) say the high fiber count is crucial. "Hands down, my male clients prefer smoothies," says Kimberly Snyder, a celebrity nutritionist. Snyder says her clients "feel more satisfied, stay fuller longer, and experience long-lasting energy."

With the stakes so high (Starbucks splurged $70 million on a new Evolution Fresh juice factory), it's no surprise that the argument is heated. Take, for example, Marcus Antebi, of the New York City chain Juice Press, who has claimed he "waterboarded [the competition] with green juice." Or Neka Pasquale, of San Francisco's Urban Remedy—she's gone on record slamming boutique-juicery owners who went over to the dark side by using preservation methods to keep beverages on shelves longer. "You might as well drink sugar water," Pasquale says of the process.

Whether you're ready to take sides or are already on one, here's a field guide to the juicing universe.

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High-Pressure Pascalization, or HPP
A shelf-life-extending technology that uses pressure to kill pathogens—and also nutrients, according to critics of the method.

Centrifugal Juicer
A machine that uses a flat blade to grind produce and a spinning motion to force juice from pulp. A by-product is heat, which opponents say "cooks" the ingredients.

Live Enzymes
The biologically active proteins found in raw foods. Cold-pressers claim their juice offers the most of these (no heat) the most efficiently (no fiber).

A liquid-nutrient aficionado who proudly shows off his pre-pulverized haul via social media to brag about the amount of produce he ingests.

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A Brief History of Juicing

1930s: Dr. Norman W. Walker invents the first hydraulic-press juicer, the Norwalk—still the industry gold standard.

1940s: The Master Cleanse is developed by Stanley Burroughs to treat maladies; it eventually becomes popular for weight loss.

1960s: Macrobiotic vegetarianism spurs health-food eateries to start serving the first smoothies: blended fruit, fruit juice, and ice.

1990s: Jamba Juice launches in California, selling frozen-yogurt-laden "smoothies." Nutritionists later label them as calorie bombs.

2010s: Boutique juice is big business as investors snap up companies (BluePrint for $25 million; Organic Avenue for an undisclosed sum).