Pregnant and cheese

Many pregnant women do not eat foreign cheese during pregnancy for fear of the infamous Listeria bacteria. However, if you look closely at the cheese preparation process, it appears that there are very few cheeses that actually pose a danger. Only the soft cheeses made from raw milk can pose a danger. The vast majority of cheeses can therefore be eaten when you are pregnant.

Cheese during pregnancy

Cheese contains a lot of calcium, vitamin B12 and vitamin D. Calcium is essential for building the bones of the baby. Vitamin D ensures a good absorption of calcium. Most varieties contain enough calcium in one serving of cheese for 25% of the Recommended Daily Allowance (RDA).

Cheese consists mainly of milk. Cheese is made by adding rennet and starter culture to the milk. This causes the casein proteins to clump together, making the milk thick, creating a curd. The curd is cut and then pressed together. The moisture that comes out is the whey, which consists mainly of water, milk sugars and whey proteins. In the compressed curd it is mainly the fat and casein proteins that remain.

With soft cheeses, the curd is not cut, but placed entirely in a cheese mold. The meadow will then slowly run out. When preparing cream cheese, the cheese is already ready after draining. When preparing fungal cheeses such as brie and camembert, the cheese is rubbed with a fungal culture and will then ripen for a number of weeks. The soft cheese mozzarella is often heated in hot whey, which makes the cheese elastic. There are also soft young cheeses that are made by bringing the acidified milk to a boil and compressing the curd pieces that form.

With hard cheeses, such as Dutch cheese, the curd is dipped in a brine bath. This will make the cheese saltier, give it a crust and make it firmer. These cheeses contain less moisture and more salt and therefore have a longer shelf life.

Whether there are bacteria in cheese depends on whether the cheese is made from raw milk or pasteurized milk. Raw milk can be contaminated with bacteria through the udder when the cow is milked. Pasteurized milk is heated to 72 degrees, which kills most bacteria. Pasteurized cheese is therefore a safer raw material for cheese than raw milk and most cheeses are made from pasteurized milk. However, there are cheeses that are made from raw milk, such as Brie de meaux, farmer's cheese, Camembert au lait cru, Roquefort or Reblochon cheese. However, it depends on the method of preparation whether certain bacteria can grow further in these cheeses.

Listeria is a pathogenic bacterium that is dangerous for the unborn child because it can pass through the placenta. Research in the US shows that 16 to 90% of the victims of Listeriosis are pregnant. Pregnant women have been found to be 20 times more likely to develop Listeriosis than healthy adults. In pregnant women, Listeria can cause fever, chills, muscle pain, flu-like symptoms, premature births, stillbirths, inflammation of the amniotic membranes and inflammation of the uterus (neck). Listeria, unlike most other bacteria, can grow at low temperatures and relatively little moisture. The bacteria grows best in an oxygen-poor environment. However, the bacteria cannot grow in an environment with too little moisture, a lot of salt or in an acidic environment, as is the case, for example, in Gouda cheese. Listeria has also never been found in goat cheese, probably because fresh goat cheese is often more acidic, which means that the Listeria cannot grow. Also in the blue cheese Roquefort, which is made from sheep's cheese, Listeria has never been found.

It has been found that Listeria regularly occurs in raw cow's milk. This means that cheeses made from raw milk can contain Listeria. Because the bacteria grows at refrigerator temperatures, cheeses that have been ripened for some time are particularly at risk. Examples are Brie and Camembert from raw milk. Whole fresh raw milk cheeses, such as cream cheese, could in theory also contain Listeria. In practice, however, these are always made with pasteurized milk, which reduces the risk of possible contamination. Even so, a Listeria contamination in soft cheeses made from raw milk is possible, because the pasteurized milk can be contaminated afterwards. Listeria can leave a biofilm on stainless steel and rubber, two commonly used materials in the food industry. If the pasteurized milk or cheese comes into contact with these materials, Listeria can still grow into these cheeses. Hard cheeses made from raw milk, such as Dutch farm cheese, are not a source for Listeria because of the lactic acid and drier character.

If we look carefully at which cheeses pose a real danger to pregnant women, few cheeses are left. Most cheeses are therefore safe to eat. Safe means that the risk is so low that it is not necessary to avoid these products. The table below provides a clear overview of which cheeses are and which are not safe during pregnancy.