Powders, pills and drinks made from ingredients like wheat grass, alfalfa, kelp, spirulina, chlorella, leafy vegetables and fruits are a popular choice for people looking to increase their intake of vitamins, minerals and other plant-based nutrients. However, recent tests by ConsumerLab.com (White Plains, NY) of “greens” and “whole foods” products revealed that four of 13 products exceeded limits for lead. One of these four was also contaminated with cadmium, while another was contaminated with arsenic. The findings were confirmed in a second, independent laboratory.

None of the products were contaminated with pathogenic bacteria or yeast or with dangerous pesticides. All products labeled as “gluten free” were found to meet the claim.

As part of its review, ConsumerLab.com also compared products on cost, which was found to range from just 31 cents to $4.35 for a single serving—and some of the most expensive products were among those which failed testing. ConsumerLab.com also found that the high levels of vitamins and minerals in some products could cause a person to exceed upper tolerable limits, above which there is a risk of toxicity, especially if having more than one serving daily or if given to children.

“These products can provide important nutrients, but they should not be considered a substitute for whole fruits and vegetables,” said ConsumerLab.com President Tod Cooperman, MD. “Most importantly, they should not put you at risk of harm.” Among products which were Approved, ConsumerLab.com identified its Top Picks.

ConsumerLab.com’s Review of Greens and Whole Food Powders, Pills and Drinks is now available online here.

The report also summarizes the evidence for certain greens ingredients and discusses claims about antioxidant activity and alkalizing effects, as well as safety concerns and potential side effects.