You started investigating the sugar industry after attending a dental conference on diabetes. Why?
I got a government brochure about preventing diabetes, and the nutritional advice was to reduce calories, increase fiber, decrease fat. It didn’t say anything about sugar. One of the speakers had a fast-food nutrition guide, and [a sweet tea] got ranked as a “healthy.” I asked him, “How can you characterize sweet tea, which has a ton of sugar in it, as a healthy drink?” His response was that there’s no evidence linking sugar to chronic disease. I just looked at him like, What?
So that led you to start digging into how industry was affecting public-health messaging?
I came across all of these references to the Great Western Sugar Co. The company was based in Denver, and sugar beets were historically a major crop in Colorado, so the company decided to donate many of their records to local libraries. In the first folder that I opened, there was a confidential memo with the Sugar Association’s letterhead on it. I was like, What did I just find? Are you kidding me?
What did the memo reveal?
It was a memo the Sugar Association sent out to its PR guys at various sugar companies about a report they had put together called Sugar in the Diet of Man. The report, which they put together with consultants, was meant to be a review of all the scientific research about sugar, heart disease, diabetes, tooth decay, obesity, etc. Of course, it ultimately concluded that sugar didn’t have a role in any of those things.
Your most recent research showed the sugar industry funded studies blaming fat instead of sugar as the leading cause of heart disease.
I don’t think we realize how much we’ve been marketed to. The whole “low-fat is healthy” movement allowed products high in sugar to be promoted as healthy. I don’t think the average person really grasps that there is industry money behind many food- and health-related studies.
Do you think Americans are catching on?
We’re in a time now where Big Soda is fighting the soda taxes, and the public is waking up to industry tactics. There’s a whole movement of trying to increase people’s awareness of food.
What needs to change?
Even though the science is clear that sugar contributes to heart disease, we’re still having these same debates about the role sugar plays in people’s health. I think my research can help us understand why these debates have gone on for so long. The tobacco industry still funds research, but the more high-quality, respectable journals have refused to publish it. That hasn’t happened yet in the food world.
Has your own diet changed?
I used to drink soda instead of coffee. That was a long time ago.
Do you consider yourself an activist?
That gets turned into sort of a bad word sometimes. I am taking action, let’s put it that way. I really want evidence to support what I’m bringing to light. I don’t want to just point the finger and say the sugar industry is bad. I want to document what they’re doing. I want the work to lead the way, and not have it be about me.
Many of your colleagues describe you as soft-spoken. Are you?
People don’t expect me to come out with the material I have. Because I am not preachy, people seem to trust me as reliable. I’ll take it. That’s who I am. I’m a proud introvert.
This appears in the December 26, 2016 issue of TIME.