Listeria: I’m pregnant, can I eat…

  • Can I eat soft cheese, blue cheese, goats cheese?
  • Can I eat pâté?
  • Can I eat cold cut meats and smoked fish?
  • Can I eat ice cream?
  • Can I eat cold cooked prawns?
  • Cani eat pre-packaged sandwiches, melon or anything at all?

All of these questions relate to Listeria. There’s a good page on what Listeria is (called listeriosis which is the name given when someone is infected) on the NHS choices site.

But here are a few important points about Listeria:

  • It’s a bacterial infection.
  • It’s all around us and can get into almost any food.
  • Cooking kills it, so if you’re eating a hot (cooked to 70 C) meal you’ll be fine. 
  • While most bacteria do not grow well in a fridge (that’s why we use them), Listeria is different. Once Listeria is in a food it can multiply quickly, even if it has been refrigerated properly. 
  • Symptoms can take 3 months to appear and are usually mild flu-like symptoms or stomach upset, or no symptoms at all.
  • In the elderly and those with weakened immune systems it can be serious. 
  • Pregnant women also often have very mild illness, but it can cause miscarriage, stillbirth, or serious infection in the newborn baby. 

Deciding what foods to avoid: Listeria
Listeria: Balancing the risks

Serious stuff, and one to be avoided at all costs then!! 

Before we get too scared, it’s worth remembering the number of cases each year are low. Between 2004 and 2014 there were an average of 180 cases a year in England and Wales, and in 2014 only 21 of those were pregnancy-associated (either mother or infant) [here’s the data]. Case numbers will be low, in part, because we tell people to avoid high risk foods. There no data as to whether those infected were following the current NHS guidelines, though in France, 80% of infected women reported eating high risk foods [French data here]. 

But what are those high risk foods?

Can I eat cheese? Yes, but some cheeses are a risk. Soft, mould-ripened or blue veined cheese (details on which cheese this means is on the NHS choices site) is a well documented risk. The moisture content makes them particularly suitable for Listeria growth. Hard cheese, (cheddar, Stilton etc) with less moisture, are very low risk, but bear in mind that if you’re buying low risk cheese from areas where high risk cheese is served (e.g. a supermarket cheese counter or deli) there is the potential for bacteria to be transferred from high risk cheese to the low risk cheese (cross-contamination). 

A point of confusion is pasteurisation. As the cheese may be affected after this process, it’s not protective. Pasteurised Brie is still high risk. Unoasteuried cheddar is still low risk.

Can I eat pâte? Not if you want to avoid Listeria high-risk foods. It’s the moisture content again I’m afraid, and includes vegetable pâté and fois gras.

Can I eat cold cut meat? This one is a little less clear cut. The NHS choices site says to cautious of cured meats as they pose a risk of toxoplasmosis (I’ll cover this on another post soon) as they haven’t been cooked, but there’s no mention of Listeria. However, the risk of Listeria in cold cuts of meat (including packs of cooked ham) is not zero. Here’s a report of an outbreak linked to deli meat in Canada, and a recent recall notice from the Food Standards Agency just to prove the point. In the UK it has been decided that the risk is low enough not to worry pregnant women. The NHS do acknowledge that this stance is different to other countries, but don’t detail why. 

The US, for example, advise against the consumption of cold cuts of meat (here’s the US Center of Disease Control page). Now some of the difference may be due to the differing eating habits of the US, and some due to cultural differences – the US does tend to be more cautious with a lot of health advice. Maybe there are differences in contamination levels in products consumed in the two countries, or testing procedures of products before they reach our supermarket shelves, though I’m not convinced that this is the case. Regardless, the difference in guidelines definitely made me uneasy when I was pregnant (incidentally, the French also caution against eating cured or cold cuts of meat due to the Listeria risk). 

Confusing, huh? This is where women need to decide what level of risk they are happy with. Listeria has been isolated from many food sources, some of which you’d never guess (Cantaloupe melons, anyone) and you can’t totally eliminate all risk. If you eat cold cuts of meat, the chance of contracting Listeria is tiny…but it is there.

Can I eat smoked fish? Another murky decision process I’m afraid. In the UK we are advised that smoked salmon is safe, but again the NHS acknowledge that other countries have different guidelines. Again, the US and France advise against consumption of smoked or cured fish when pregnant. Again, there’s definitely a risk there. Heres a recent recall alert from the Food Standards Agency. Note though, while smoked salmon was found to contain Listeria, that didn’t translate into any human cases that we’re aware of. Again, pregnant women need to decide for themselves what they are comfortable eating. Sorry!!

Can I eat ice cream? This was a new one on me, but looking at some mum/baby forums, I could see it was a particularly common question. There’s no mention of it on the NHS site, or US equivalent. Soft-serve ice cream (McFlurries, Mr Whippy etc) are mentioned as a risk in some Australian advice, however. The risk from conventional ice cream is low – Listeria won’t grow in frozen products. The issue with soft-serve is that it is stored in the fridge (where Listeria can grow) and only frozen when they serve it. That, and it comes out a tube that is hard to clean. However, newer machines used in the major chains are self-cleaning. I can’t find any reports of cases being associated with soft-serve ice cream and, in fact, most recalls appear to be linked to traditional ice cream. My verdict would be that eating McFlurries are pretty safe.

Can I eat cold, cooked prawns? While prawns served hot are fine, there is a theoretical risk from packs of cold prawns. While I’m not aware of any outbreaks linked to them, in one study they were more commonly eaten in elderly cases of Listeria than in a reference population. 

Any other risks? As I’ve mentioned, there are lots of potential sources of Listeria – almost anything you’re eating that isn’t warm really. But, the risks from most of these are minuscule and uncontrollable – the detrimental affect of eliminating all cold food from your diet (for your stress levels as well as your nutrition) far outweigh the likelihood of contracting Listeria infection, in my opinion anyway. Pre packaged sandwiches have been reported as a risk, mainly in a hospital environment, and admittedly not in pregnant women…still might be worth a thought though. A recent recall of double cream by the Food Standards Agency highlights that relatively safe products can still be a risk, but that there is monitoring in place, and in most cases affected products don’t translate into human cases. The Australian advice is the most cautious I’ve seen and also mentions pre packed salads as a risk. I’m sure they are, but then anything that isn’t eaten hot presents some risk.

What did I do? 

In this instance I decided that the repercussions of Listeria infection were too severe for me to risk any high risk foods. That’s not to say that others will come to the same decision – I was in a position where I was acutely aware of the risks and this probably coloured my decision. It’s personal thing. I avoided all the high risk foods. I also avoided smoked fish, cold prawns, cured and cold cut meats, and pre-packaged sandwiches (I got up 10 minutes earlier and made my own – saved me some money along the way too). Then, as an extra precaution, I avoided things like meat and cheese counters at supermarkets as I thought the risk of cross contamination (bacteria being transferred from a high risk cheese to a low risk cheese when cut, for example) was too high [here’s an outbreak where they thought cheese was probably subject to cross contamination, and another one!]. I didn’t avoid soft-serve ice cream as I didn’t realise it was considered by some to be high risk…but don’t think I ate any while I was pregant!

So, in conclusion, Listeria is a very serious infection for pregnant women and their babies.  Any food can carry Listeria, some are more risky than others, but there’s no definitive way of avoiding all risk. Women need to be armed with the facts to make the right decision for them and their babies.