Overinterpreting diet and asthma

The Herald’s lead

Eating fast food and consuming sugary drinks renders the most common asthma inhaler ineffective, a study warns.

This is two studies. One looked at a ‘dietary inflammation index’ and whether people with higher values were more likely to be asthmatic. It did not look at inhaler effectiveness at all.  The dietary inflammation index does not measure ‘sugary drinks’; it treats all carbohydrate the same. It doesn’t directly measure fast food, though it does distinguish different types of fat.  Since the dietary inflammation index, according to the paper that proposed it, is relatively weakly associated with biological measures of inflammation,  the strong association seen in this study between the index and asthma may just mean that other factors are affecting both asthma and diet.

The other study looked at how salbutamol, the active ingredient of the Ventolin inhaler, was absorbed in samples of lung tissue in the lab. The amount of polyunsaturated fat affected absorption — but that wasn’t dietary fat and there weren’t any inhalers, or any sugary drinks.  Further research might show this translates into real differences in inhaler effectiveness, or it might not.

So, while there is actual science described in the article, there is almost no support for the lead. No inhalers, no sugary drinks, no fast food.

You might also wonder why the Herald is getting a comment from Asthma UK for research presented at a conference of the Thoracic Society of Australia and New Zealand. Or not.