This story about lycopene for the prevention of stroke had two glaring problems: It provided relative instead of absolute risk numbers, and had a headline that was more forceful than the underlying evidence can support.
But the rest of the story had a wealth of information that readers should find very helpful, including discussion of confounding factors that might have skewed the results, some very thoughtful expert perspectives, and a warning that no one food or nutrient is responsible for the benefits of a healthy diet.
For years we’ve been hearing about the benefits of this or that “superfood” with the most antioxidants. But the reality is that there’s no strong evidence to support the health benefits of any particular fruit or vegetable over any other. All fruits and vegetables contain antioxidants and other nutrients that are important for health, and it’s the combination of fruits and vegetables in a healthy diet that seems to offer the most benefit for preventing chronic diseases. Anyone who says otherwise is probably either: a) trying to get a study published, or b) trying to sell you something, or c) both.
The cost of tomatoes, or other food sources of lycopene, is not in question.
The story frames the benefit in relative terms, stating: “…those with the highest levels of lycopene were 55% less likely to have a stroke than those with the lowest amounts in their blood.”
But since we don’t know how many strokes occurred in these high- and low-lycopene groups, there’s really no way to tell how meaningful this 55% reduction is. The story would have done better to put the statistics in more useful absolute terms, as a press release that accompanied the study did: “Among the men with the lowest levels of lycopene, 25 of 258 men had a stroke. Among those with the highest levels of lycopene, 11 of 259 men had a stroke.”
We don’t know of any harms that can result from eating tomatoes, so we’ll rule this not applicable. However, the story could have cautioned against trying to get lycopene from supplements, which could have unknown side effects and harms.
This story draws a red flag for violating our cardinal rule of reporting on observational studies. The headline claims that tomatoes “may help reduce stroke risk,” suggesting a cause and effect relationship between tomatoes and stroke. But as we’ve noted many times before, observational studies such as this one are incapable of proving such a link, so it is inappropriate to use active, causative verbs (“may reduce,” “may protect,” “could lower”) to describe the results.
That weakness aside, the story included lots of good information to help readers make sense of the findings. Some notable strong points:
There was no disease-mongering of stroke. However, the description of free radicals did sound a little alarming. They are natural byproducts of our biochemical processes.
There was excellent input from independent experts on stroke and nutrition. This was a strength of the story.
The story suggests that we consume a mix of fruits and vegetables every day, because, as one expert put it: “…we don’t know if there is really anything unique about tomatoes apart from other fruits and vegetables that reduce stroke risk.”
The story could have mentioned other controllable factors associated with stroke risk, including tobacco use, obesity, and heavy alcohol consumption.
The availability of tomatoes is not in question.
The story doesn’t hype the novelty of the research. As one source comments, the study “…fits with other data that we have about risk of stroke and vegetable and fruit consumption.”
There is enough independent perspective in this piece that we can be sure it wasn’t based on a press release.