How do I tell my brother his diet could be harmful?

You articulate it as worrying about his health, but I think it goes deeper than that, says Annalisa Barbieri

I'm in my late 40s and have a brother who is a couple of years younger than me. He's been happily married for almost 20 years and has a lovely daughter, who is in her early teens.

Some years ago, he was treated for cancer (he has been in remission since), and I am happy he has managed to find his way in life. Our parents died two years ago, and we are all the family we have; we've had our differences, but in reconciling we probably understand each other better than ever.