 What about the microscopic greens, like spirulina? Of all the controversial findings I've shared from the medical literature over the years, this is the one I get the most mail about. People love their ponds gone. So I've stayed on top of the literature, and it's time for an update. There's no doubt that spirulina does some amazing things, but as with everything in life, it's all about risk-benefit. And so although in 2007 the data pointed against spirulina, and I threw mine out and encouraged others to do the same, is it possible that the balance of evidence has shifted back in favor? Still harmful? Half and half? Or crept back to helpful? In 2007 I was concerned about spirulina because of muscle breakdown, and these new findings have me concerned about liver cancer, too. 94% of samples were found to be contaminated with hepatotoxic microcystin toxins.