Are Greens Powders Worth It?

If you type "greens powder" into Google, it suggests finishing the sentence with "makes me poop," "making me bloated," and "vs multivitamin." If you type "is ag1," the first suggestion is "worth it." For most healthy students the answer is no. A greens powder is either a multivitamin you drink or, in Bloom's case, mostly fiber, grass, and algae powders, with a small amount of dried fruits and vegetables mixed in. Every published trial of AG1, the best-known brand, was paid for by the company, and the two that measured digestion couldn't show that it did better than a placebo (a fake powder with nothing active in it).

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What's actually in a scoop?

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Bloom's Berry flavor scoop weighs 5.44 grams and has 15 calories. Its label lists a "Fruit and Vegetable Blend" of carrot, beet, kale, blueberry, spinach, broccoli, and ginger that weighs 572 milligrams in total, which is about a tenth of the scoop. The rest is split between other blends (barley grass, spirulina, berry powders, digestive enzymes, and herbs like ashwagandha), plus flavor and stevia. Besides sodium, iron is the only mineral on the label, and there are no vitamins listed at all.

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AG1's 13-gram scoop has 40 calories and 2 grams of fiber, and its label reads like a multivitamin's: 500 milligrams of vitamin C (556% of what you need in a day), vitamin B12 at 16,667%, biotin at 1,100%, and a long list of others. The plants are in two blends, an "Active Superfood and Prebiotic Complex" (7.5 grams) and a "Daily Phytonutrient Complex" (1.5 grams), each listing a long run of powders and herbs with no amount next to any of them.

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The FDA (Food and Drug Administration) lets supplement makers list a "Proprietary Blend" by its total weight and the names of what's in it, without saying how much of each ingredient there is, so both labels are legal. It also means that you can't tell how much broccoli is in either scoop, and some of the ingredients could be there in amounts too small to do anything.

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If you searched "greens powder vs multivitamin," AG1 is a multivitamin in drink form, and the NIH Office of Dietary Supplements (the US government's office for supplement research) says that "no U.S. government health agency, private health group, or health professional organization promotes regular use" of multivitamins. It adds that they "cannot take the place of the variety of foods that are important to a healthy diet."

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Does it do anything for your gut?

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AG1 has published two gut studies, and people who work for the company are authors on both. In the first, 30 healthy adults aged 18 to 50 took AG1 or a placebo for four weeks. The paper says it was "funded in part by AG1," and two of its authors work there. A few types of bacteria went up in the AG1 group, and the authors write that the two probiotic ones "likely stem from the probiotics species that exist in the product," so the bacteria that went up were largely ones that AG1 puts in the scoop. People's digestion scores improved more on AG1 than on placebo, but not by enough to rule out chance (a p-value of 0.058, just over the usual 0.05 cutoff).

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The second study gave 20 people who lift weights, averaging about 26 years old, two weeks of AG1 and two weeks of placebo. There were "no significant differences in digestive quality of life" between AG1 and placebo. Some bacteria went up again, and the paper says that those changes "were lost" after two weeks off the powder.

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AG1's website has also pointed to a study where people said they felt less bloated. Jonathan Jarry at McGill University's Office for Science and Society (a group that fact-checks health claims) points out that it had "no control group," that people rated themselves, and that "only 35 adults participated." JoAnn Manson, a Harvard Medical School professor who runs large supplement trials, told Fortune, "These are very small randomized trials," and compared them with a multivitamin trial her team ran "with 15,000 participants for 11 years."

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Bloom doesn't have a published trial of its greens. Searching PubMed (the US government's database of medical research) turns up no study of the product.

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If changing your gut bacteria is the goal, the probiotic part of these powders runs into the same problem as probiotic pills, and the prebiotic part is fiber you can get from food. The prebiotics article covers the difference.

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Why would a greens powder make you gassy?

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The fiber in Bloom comes from chicory root fructo-oligosaccharides (short chains of a sugar called fructose, often shortened to FOS) and agave inulin, and AG1 lists chicory root inulin too. Both are fermentable fibers, which means that the bacteria in your colon eat them and make gas while they do it. In a 2010 trial of 26 healthy adults, inulin fibers "tended to increase GI symptoms mildly," and the most common symptoms were gas and then bloating. The same trial found that up to 10 grams a day of regular inulin and up to 5 grams of the shorter kind (oligofructose) were "well-tolerated in healthy, young adults."

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Bloom lists 2 grams of fiber per scoop, which is well under what that trial found people handled fine, so for most people a scoop shouldn't cause much gas. If a scoop does send you to the bathroom, stop taking it. The fiber-maxxing article has more on how much fermentable fiber people can handle.

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Who might it help?

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Yasi Ansari, a senior dietitian at UCLA Health, says that people who find it hard to eat enough fruits and vegetables, "or who have limited access to fresh produce may benefit" from one. Cleveland Clinic's Julia Zumpano, a registered dietitian, calls powdered greens "a bonus," and says that if you're already eating plenty of fruits and vegetables, they "may not be necessary."

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Both of them say that a powder can't replace the food. "You never want powdered greens to take the place of eating whole fruits and vegetables," Zumpano says. Ansari says that whole fruits and vegetables give you plant compounds that work together "in a way that powders can't replicate," and that "many of these compounds haven't been studied extensively in powdered form or in combination with dozens of other ingredients."

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Mayo Clinic Press says that most greens powders have "only 1 to 2 grams of fiber per serving," while the daily recommendation is 25 to 35 grams. Bloom and AG1 both list 2, so a scoop covers less than a tenth of the day.

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Can a greens powder hurt you?

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The FDA "does not have the authority to approve dietary supplements before they are marketed," so nobody checks a tub before it goes on sale, and problems get caught afterward. Live it Up recalled all of its Super Greens powders for salmonella, and the CDC (the US government's disease-tracking agency) ended up counting 131 sick people in 38 states, 36 of them hospitalized, in an outbreak it traced to moringa leaf powder, a dried-leaf ingredient used in several brands.

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Cyanotech, a company that makes spirulina, paid outside labs to test 37 best-selling greens and spirulina powders for lead, and 8 of the 13 organic mixed greens powders went over the lead limit for California's Prop 65 warning labels. Cyanotech sells a competing product, and a Prop 65 limit is the level that triggers a warning label, not the level where harm starts. A group called Environmental Health Advocates has also filed a Prop 65 notice over lead in Bloom's Inbloom Daily Greens & Multivitamin, which is a legal warning that a lawsuit may follow, not a ruling that the product broke the law.

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The American Academy of Pediatrics (the main group of children's doctors in the US) says that healthy kids eating a normal diet "do not need vitamin supplementation over and above the recommended dietary allowances," and that "megadoses of vitamins" can cause "toxic symptoms." If you already take a multivitamin, drink energy drinks with added B vitamins, or eat fortified cereal, the vitamins in a powder like AG1 stack on top of all of it. Cleveland Clinic also notes that many greens powders are "high in vitamin K," which matters if you take a blood thinner.

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Is it worth the money?

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AG1 costs $99 for a 30-day pouch, or $79 a month on a subscription ($2.63 a serving). Bloom costs $33.99 for 30 scoops, or $1.13 a serving. Manson's point about AG1 applies to all of them: "People are still going to have grocery bills if they use this product." If you eat almost no vegetables and a greens powder is the only green thing you'll realistically have, it can fill in some vitamins. If you already eat some fruits and vegetables, the same money buys more of the food the powder is trying to imitate, with the fiber still in it.

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