By Tanner Garrity Back in 2015, The Washington Post ran the headline: “This is America’s favorite dietary supplement, even though the benefits aren’t proven.” The article was about fish oil, which, at the time, had turned into a $1 billion industry. In the years since, that valuation practically doubled, to $1.9 billion in 2019. And by 2027, the market for fish oil is expected to balloon up to $2.8 billion, in lockstep with the rest of the surging supplements space. What happened? How did America go from loving fish oil to really loving fish oil? Did researchers finally prove those purported b…