Do greens powders do anything?

What the evidence says

Greens powders are blends of dried fruit, vegetable, algae and herb extracts that you mix into water, marketed as an easy way to get extra plant nutrients. The idea sounds appealing, but the science behind these products is much thinner than the marketing suggests.

A few small human trials exist. One found that a commercial greens powder increased the amount of antioxidant activity in people's blood after four weeks, in a dose-dependent way, and reduced some markers of fat and protein damage in blood samples. Another small trial on a different greens powder found it was safe over four weeks and was linked to some improvement in digestive comfort, though it did not meaningfully change the mix of gut bacteria.

The problem is these studies are small, short, and measure blood markers or symptoms rather than things that actually matter long term, like whether people get fewer heart attacks, less cancer, or live longer. Some of the research was also funded by the companies that make the product, which is a known source of bias in nutrition research.

Health Canada's general guidance on dietary supplements applies here too: supplements cannot replace the nutrients and fibre you get from whole food, and manufacturer claims are not always verified. Even certified products aren't checked for whether their health claims are actually true, only whether the label matches what's inside.

So greens powders are probably not harmful for most healthy adults in normal amounts, and small studies hint they might nudge some blood markers in a positive direction. But there is no strong proof they replace real fruit and vegetables or improve long-term health, so eating whole plant foods remains the better-supported choice.