Continuing the Conversation With
Kevin Hall

One of the topics addressed in the IFT FIRST session was the importance of identifying the mechanisms by which ultra-processing causes food to be unhealthy. What kind of research is needed in this area?

When we published our study, which is still the only randomized control trial published on this, it wasn't designed to investigate mechanisms. It was simply designed to ask the question, if you actually normalize for a bunch of the nutrients that we think might be playing a role, do we still see an effect of ultra-processed foods? And the answer was yes.

[It] doesn't say how that happened or what the mechanism for it was. And that's only for one particular outcome, which was overconsumption of calories and weight gain. So the idea [now] is to subcategorize the potential poor health consequences, different outcomes, whether or not there are biomarkers that you could measure in the short term that would give us some insight along the causal pathway and [then] make manipulations of the foods and the compositions of the diets along the hypothetical pathways.

So, for example, we heard that one proposed mechanism might be protein oxidation as a result of the high heat and high temperature and high pressure and sheer stress … that are involved in making some of these alternative proteins. Maybe that's leading to some toxins and difficulty digesting and absorbing. So that's a plausible hypothesis. You can measure certain qualities of the food that might be different between different kinds of processing, but at the end of the day, you still have to test it in humans.

A recent study from researchers at the Harvard T.H. Chan School of Public Health suggests that some kinds of processed foods, including processed meats and sugar-sweetened beverages, are more likely than others to have a negative effect on health. Do you agree with that assessment?

Absolutely. … [Just because a food is ultra-processed] doesn’t mean that nutrient profile isn’t important. … So, for example, even just within ultra-processed foods like the bread category, there are ultra-processed breads that have poor nutritional profiles. There are others that have much better nutritional profiles. So you don't have to ignore nutritional profiles.

I think it makes a lot of sense, until proven otherwise, that one of them is going to be much more healthy for you than another. Now is a minimally processed version like an artisanal baked bread that's not precut or something like that, is that going to be even better for you? Maybe. But until we know that, we have to consider all these other factors like nutrient profile, as well as convenience and taste and expense, so all of these things are weighing into people's choices.

You mentioned a role for food scientists in research into the impact of ultra-processed foods on health. Tell us about that.

We’re really interested in collaborating with food scientists to design better studies. … We need food scientists and technologists to partner and form multidisciplinary teams along with nutrition scientists and clinicians to do clinical trials and design diets. … And hopefully we can get funding in order to form these multidisciplinary teams to, number one, narrow down what are the top hypothetical mechanisms [and] what are the categories of foods that are engineerable along those hypothetical mechanisms? And then [we need to] conduct randomized controlled trials to demonstrate whether or not those reengineered foods are actually successfully ameliorating the negative health consequences.ft