20 July 2026

I went for a swim on Wednesday morning without checking the air quality, and it was not pleasant. In fact, I had to cut my swim short, which got me thinking… is swimming even healthy when the air is filled with toxins from wildfires?

Answer: If the air quality index is over 150 (100 for sensitive groups), probably not.

But I have more questions.

Are leafy greens healthful when there’s a cyclospora outbreak?

Are the benefits of fruits and vegetables now being surpassed by the dangers of pesticide contamination?

And a recent study out of USC found a link between eating lots of fruits and vegetables and non-smokers getting lung cancer. Nota bene: correlation does not equal causation.

As someone who has made a career out of helping people consume more vegetables, I had to know. My instinct - based on decades of education and work experience - was that these dangers were being exaggerated. Influencers and researchers alike are competing in informational flood-like conditions to get the consumer’s attention. Shock and surprise gets views.

But we don’t know until we look into the data.

Regarding the lung cancer study, the researchers didn’t immediately jump to the conclusion that fruits and vegetables cause lung cancer (because decades of research had demonstrated a protective effect for other types of cancer). They realized that the study led to more questions about environmental factors that may be at play. One possibility was increased pesticide exposure (since higher rates of lung cancer were also found in agricultural workers), but we still don’t know.

What we do know is that consuming the recommended servings of fruits and vegetables (which may vary by individual, but generally means 5+ servings per day) is associated with a reduced risk of heart disease (a condition that kills nearly a million Americans every year), cancer and all cause mortality.

Putting this into perspective, based on current data, a healthy diet (according the to Healthy Eating Index, where most Americans score a 57/100) could have the following impact on the US population of 340 million adults (and I think these estimates are conservative):

• 20-30% fewer heart disease deaths, or ~200,000
• 10-20% fewer cancer deaths, or ~100,000
• all cause mortality - 15-30% fewer deaths, or up to 900,000

Compare that to the increased relative lung cancer risk (which has not been consistently shown across studies, and which is not linked to a similar increase in deaths from lung disease) of 5-15% . This means, with current rates of new diagnoses, the chance of getting lung cancer increases from .067% to .077%.

So the math puts better odds on healthy eating keeping us healthy. Of course, none of that matters to you if you’re part of that 0.01% difference who experiences lung disease, or any other chronic disease for that matter. Data is not individual; it’s population based.

But humans are notoriously inept at assessing risk in our own lives.

There’s a difference between the hazard analysis (the possibility of any particular lifestyle behavior or chemical causing harm) and actual risk assessment, which is based on the extent and intensity of exposure.

With the cyclospora outbreak, there’s an extremely low risk of death, only a danger of severe or long illness if left untreated, especially in people with compromised immune systems. The choice, however, need not be to avoid all leafy greens - or even just lettuce - forever. We can take conservative steps to limit the danger.

• Avoid food or water that has been contaminated with feces (sadly, sometimes easier said than done). I’d limit nationally produced bagged leafy greens for now - those grown in your own garden or by a local farmer ought to be ok.
• Wash hands, countertops and utensils with warm, soapy water (20 seconds!) before and after handling/preparing any raw vegetables or other food.
• Cooking foods to 158 degrees kills the parasite, so cooked veggies are still on the menu!

With so much complicated - and sometimes conflicting - data out there, how do we make the right choice for our health? One powerful thing we can do is focus on frequency over fear. When you stop to think about how often something happens - even if it’s an extremely scary thing - it’s a bit easier to assess the real danger.

Recognize that some things are out of our control. We can acknowledge uncertainty and also do the best we can based on evidence, more than emotion. Stay well!