Maybe it’s just my age (40-something) but it seems that just about everyone around me knows someone who has cancer. One of my very close friends doesn’t have cancer any more – they chopped it out. But now she is going through the gruelling process of chemotherapy. Fifteen weeks into her treatment and she is still the most positive, happy person I know! Her doctors are amazed at her attitude and progress.

A few weeks ago I dropped off some food to her – and a brochure about healthy eating when your immune system is low. She rang me the next day. “I didn’t know sushi could be dangerous for me!” she exclaimed. “I’ve been eating it every day. I thought it was healthy.”

Sushi is a healthy food but because it is often made a few hours before you eat it, even if it’s refrigerated, it can still harbour listeria.  You would think that if you kept a food in the fridge it would be safe to eat but unlike most bacteria listeria enjoys cold temperatures. For most of us it’s not a deadly bug and we may hardly notice if we’ve eaten some. But listeria can kill an unborn baby and certainly won’t make someone on chemotherapy feel too good.

So if you are on chemotherapy or have any long term illness that seriously whacks your immune system, stick to this food safety rule: ‘Fresh or Hot’. Apart from sushi, steer clear of these ‘high risk’ for listeria foods:

• pate
• cold pre-cooked chicken, ham, salami etc
• stored and takeaway salads
• unpasteurised milk and cheese
• brie and camembert cheese (all other cheese is fine)
• any food that has been in the fridge for more than 2 days

But don’t despair if you really want that left-over pizza from the other night. Heat it until it’s steaming (over 70C) and any lurking listeria will be well and truly dead.