You may know already that soft cheeses, smoked salmon and runny eggs are, apparently, forbidden during pregnancy. Apart from traditional Sunday breakfasts being out of the equation, many women don’t always understand the risks and reasons behind not eating these foods and spend a lot of time wondering what they can eat! It has something to do with listeria, right?
What is listeria?
Listeria monocytogenes is a bacteria found widely in nature, e.g. in soil and water, and in the intestines of many domestic and wild animals. Listeria may cause an infection named listeriosis if contaminated food is eaten. Due to the way we store, handle and consume foods, listeria is now widely transmitted by food and is found frequently in food processing environments.
What are the implications of infection?
In healthy people, listeria has little impact. However, in people with compromised immune systems, listeriosis can result in severe illness. While the incidence of listeriosis is relatively low, it is still important to take precautions to prevent infection due to the possible severity of the symptoms if infection does occur. It is particularly serious in pregnant women as listeriosis can lead to intrauterine or cervical infections which may result in spontaneous abortion or still birth.
Is it common?
Listeriosis is considered a rare disease. In Australia there are only approximately 60 cases of listeriosis each year and the majority of these are in elderly patients or people who have suppressed immune systems, for instance in people who have just had organ transplants. Less than 10 infections a year occur in pregnant women in Australia.
Despite the low numbers, it is still important to be conscious of what you are eating and how fresh it is.
What are the high risk foods?
- Ready-to-eat packaged and unpackaged meats like ham and salami from deli counters and sandwich bars
- Cold cooked chicken purchased ready-to-eat
- Refrigerated pate and meat spreads
- Pre-prepared salads from salad bars, smorgasbords and deli counters
- Raw seafood, particularly oysters, sashimi and sushi
- Smoked seafood such as salmon ready-to-eat (unless in a fully cooked dish)
- Ready-to-eat and peeled, cooked prawns (unless in a fully cooked dish)
- Soft and semi-soft cheeses (brie, camembert, ricotta, feta, blue) unless in a fully cooked dish
- Soft serve ice creams
- Unpasteurised dairy products
Main points to remember
- Avoid the above foods
- Avoid buying food from sandwich and salad bars, delicatessens and smorgasbords
- Always make sure the food you are eating while dining out is cooked thoroughly and is served hot
- Always make sure that you don’t eat food past its expiry or ‘best before’ dates
- Cook the majority of your food at home
- Be sure to always wash your hands properly when preparing food
- Storing food in the fridge or chiller does not completely prevent growth because listeria will still grow slowly at refrigeration temperatures
- Defrost frozen food in the fridge or microwave, not on the kitchen bench.
The Food Standards Australia New Zealand website has excellent information on the foods commonly affected by listeria. For further information click here.
The NSW Food Authority has a table showing what foods to avoid and what foods are safe in pregnancy. Print it off and put it on your fridge: Safer Eating During Pregnancy table
Creating a strong immune system
You may not always be able to control the way food is transported, produced or stored, but you can help your immune system to be strong enough to protect you against any type of microbe that lives on or in food.
Sometimes you may eat something that may have contained some sort of soft cheese or undercooked food without you even knowing it. Remember, serious infection is rare and partly depends on the strength of your immune system.
Following a healthy diet rich in nutrients and antioxidants, and avoiding sugar and processed or junk foods, is important for a healthy immune system and to prevent infection.
Nutrients for a strong immune system:
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Zinc: found in pepitas (pumpkin seeds), legumes, whole grains, mushrooms, green beans, meat, eggs, seafood
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Vitamin C: found in blackcurrants, strawberries, oranges, capsicum
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Vitamin E: found in wheat germ, nuts and seeds
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Betacarotene: found in carrots, broccoli, spinach, rockmelon, barley grass
References available on request