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Overview

It is easy to pull up a list online of foods to avoid during pregnancy. It may not be so easy to cut these items out of your diet. Especially if there is something on this list that you consume regularly, or really enjoy. It is not enough information for me to know I should avoid something. I want to know why I should avoid it. The truth is that during pregnancy you will eat something, likely more than once, on the do not eat list. I want to arm you with knowledge about the foods you are eating and the potential risks so you can make an informed decision about what you are comfortable eating.

Article and Resources

In this article, we are talking about foods to be cautious about during pregnancy. It is easy to pull up a list online of foods to avoid during pregnancy. It may not be so easy to cut these items out of your diet. Especially if there is something on this list that you consume regularly, or if it is a food or drink you really enjoy. It is not enough information for me to know I should avoid something. I want to know why I should avoid it. The truth is that during pregnancy you will eat something, likely more than once, on the do not eat list. I want to arm you with knowledge about the foods you are eating and the potential risks so you can make an informed decision about what you are comfortable eating.

Let’s unpack the concerns of these foods and drinks during pregnancy and while breastfeeding. I have done deep dives into some of the food or drinks we will talk about in this episode and there are additional links throughout this article.

Unpasteurized Foods (Milk, Cheese, & Juice)

Pasteurization is a process that heats foods to eliminate bacteria and pathogens for safety. This process also extends the shelf life of foods. For these reasons many of the foods that are more susceptible to harboring bacteria and pathogens are pasteurized. This primarily includes milk, juices, and some cheeses.

The FDA tested raw milk cheese aged 60 days for bacteria and pathogens. Of the 1606 samples salmonella was found in three samples and listeria was detected in ten samples.

Listeria

Listeria is short for listeriosis, the foodborne illness caused by the bacterium Listeria monocytogenes. According to the CDC, an estimated 1,600 people get listeriosis each year, and about 260 dies. The infection is most likely to sicken pregnant women and their newborns, adults aged 65 or older, and people with weakened immune systems. Several of the foods in this article always carry a risk that they are contaminated with listeria. Listeria is a bacteria that can be really harmful to your baby and it is something you would not want to encounter while pregnant.

In the FDA testing, 9 of the 10 cheeses contaminated with listeria were soft cheeses. Soft cheeses could include feta, brie, gorgonzola. These have a higher moisture content which makes them more susceptible to the growth of listeria. Of the 10 contaminated samples, 5 were domestic, 3 of these from the same manufacturer, and 5 were imported from other countries. Bottom line is that 0.62% were contaminated with listeria. If you want to avoid unpasteurized milk, juices, and cheeses you want to look for a label that says it is made with pasteurized milk.

Additives in Meat

With the high consumption of meat in the western world has come industrialization and farming that has had to grow to meet demand.  As a result of this, there may be some additives in the meat at your grocery store that you may want to be cautious about.

Antibiotics

Antibiotics are microbial drugs that treat bacterial infections. These have been given to animals since the 40s when farmers found that giving animals a constant low dose of antibiotics caused them to gain more weight. This is called sub-therapeutic use. The meat industry holds that antibiotics are necessary for the prevention, control, and treatment of diseases and infections. Farmers don’t use antibiotics 100% of the time and tend to stop using antibiotics towards the end of raising an animal to limit the amount of antibiotics in the meat.

There are maximum residue limits for antibiotics.  Keep in mind the keyword here is maximum. These aren’t banned in food, but they need to be below certain levels. One issue of high antibiotics use is that over time bacteria become antibiotic-resistant. The issue isn’t just antibiotics in the meat you are eating, but the antibiotic-resistant bacteria in the meat.  Heating meat will kill the bacteria, but there is a lot of room for contamination before this happens. Sub-therapeutic antibiotics have been banned in the European Union and Canada, but not in the U.S. Pigs have the highest use, then poultry, then beef. There are also antibiotics in farmed seafood. The Environmental Working Group has a good summary of antibiotic use in livestock.

Unfortunately, there isn’t a lot of research on eating meat that came from animals treated with antibiotics during pregnancy. If you want to avoid meat from animals treated with antibiotics you want to look for organic or something on the label specifically stating raised without antibiotics, no antibiotics ever, no antibiotics administered, no antibiotics, no antibiotics added.

Hormones

Hormones like Estradiol (an estrogen), progesterone, and testosterone are given to livestock through an ear implant. Farmers tend to refer to these as naturally occurring hormones because animals and humans do produce them. In addition to natural hormones, there are also synthetic hormones that are given to animals. Both types of hormones increase growth rate and the efficiency in which animals convert food into meat.

These hormones aren’t given to pigs or chickens because they don’t have the same growth-promoting effects. When we are talking about hormones in meat it is usually cows and sheep. You may still see something on the label of pork or chicken about not using hormones, and this is just marketing. No one is using hormones in these animals.

rBGH

One hormone that has received a lot of attention was rBGH (recombinant bovine growth hormone) this is used to spur milk production.  The concern around rBGH is that it increases the production of IGF (insulin-like growth factor), which has been linked to breast, prostate, and other cancers. Japan, Canada, Australia, New Zealand, and the EU have banned the use of rBGH. This has not been banned in the United States. It is common to see something on the label of meat or dairy products that do not use this stating, “from cows not treated with rBGH”.

There are maximum residue limits for hormones. Like antibiotics, hormones are not banned in the United States, only limited. There has been some controversy on the science of how these hormones affect humans. You know how important hormones are during pregnancy. Your hormones control everything from your cycle pre-pregnancy to your birth. Unfortunately, there are not a lot of studies on eating meat during pregnancy, and what some effects of hormone-treated beef could have on you or your baby.

For more in-depth information on antibiotics and hormones check out this episode on Eating Meat During Pregnancy.

Processed Meat, Nitrates, and Nitrites

Some meats are processed by smoking, curing, or adding salt or preservatives. Processed meat includes bacon, sausages, hot dogs, salami, corned beef, beef jerky, ham, canned meat, and meat-based sauces.

The biggest concern with processed meats is a class of synthetic food preservatives. These include sodium or potassium nitrates and nitrites. These additives are put in cured meat to preserve its color, prevent fats from going rancid and keep bacteria from growing. When nitrites are exposed to high heat they can turn into compounds called nitrosamines, which are carcinogenic, and have been linked to causing cancer. Manufacturers are required to limit the amount of nitrites they use. They are also required to add Vitamin C, which inhibits nitrosamine formation.

A study that looked at the maternal dietary intake of nitrates, nitrites, and nitrosamines and selected birth defects in offspring, looked at things like cleft lip, physical defects. This study was a large sample size, over 6,000 participants and the researchers didn’t find sufficient evidence to link nitrates and nitrites eaten during pregnancy to birth defects. Some epidemiologic studies suggest that maternal consumption of cured meat during pregnancy may increase the risk of brain tumors in offspring. One study looked at how some genes could impact a baby’s ability to deal with these carcinogenic compounds. This research did a good job of summing up some of the other studies linking nitrates and nitrates to brain tumors in children.

There are also nitrates in vegetables. So it is unlikely you are avoiding these altogether. Although vegetables generally aren’t cooked at high temps, like a hotdog or bacon. If you want to avoid synthetic nitrates and nitrites you can purchase organic, which does not allow these. You can also look for labels that state the processed meat you are buying does not contain nitrates or nitrites.

Deli Meats

Another food you should be cautious with due to the chance of listeria is deli meats. This includes any sliced meat you would put on a sandwich. There is a huge incentive for restaurants and companies who sell deli meats to make sure their foods are safe to eat. A listeria outbreak could devastate profits. One of the ways companies try to prevent listeria in deli meats is through bacteriophages, which are bacteria virus-or more simply a virus that kills bacteria. The FDA approved bacteriophages in 2006. These are sprayed directly on deli meats prior to packaging to prevent listeria. There have been concerns about the effects of bacteriophages on your gut microbiome, but more research is needed to assess that.

Of course, you could decide to eliminate deli meats from your diet during pregnancy. Another option is to eliminate the risk of listeria is to go with a hot sandwich, because heating the meat to 165 degrees Fahrenheit, or about 74 degrees Celsius will kill off the bacteria.

Fish

One of the largest benefits of eating fish is omega 3s. There are three main omega-3s: ALA, EPA, and DHA. DHA is a major structural fat in the human brain and eyes, representing about 97% of all omega-3 fats in the brain and 93% of all omega-3 fats in the retina.  DHA is particularly important for your baby’s development of their brain and retinas during the third trimester and up to 18 months of life. There is no universal recommended daily intake for omega 3s.

There are recommendations on fish intake, which purely from a numbers standpoint is the best source of Omega 3s, specifically DHA. The American College of Obstetricians and Gynecologists recommends 2-3 servings, of 8-12 ounces of fish per week. They recommend a maximum of six ounces of albacore tuna (commonly canned tuna). ACOG recommends avoiding fish with the highest levels of mercury and avoiding raw or undercooked fish.

Mercury

A concern with eating fish during pregnancy is mercury.  Mercury is an element that can collect in oceans, lakes, and streams. It turns into a neurotoxin, and in high quantities can be toxic to the nervous system.  There are four fish that are high in mercury to avoid. This includes tilefish from the Gulf of Mexico, swordfish, shark, and king mackerel. If you are eating a lot of fish from a local lake or stream check with the local advisory for mercury levels. Bacteria consume mercury and convert it into methylmercury. Plankton eats the bacteria, small fish eat the plankton, large fish eat the small fish, etc. The result is that mercury accumulates in higher concentrations as it travels up the food chain, in larger, older animals.

In humans, mercury has been shown to have an impact on the development and function of the brain and nervous system and has been blamed for developmental problems and reduced IQs in highly exposed children. The FDA has a list of Mercury Levels in commercial fish and shellfish. It is widely accepted that you want to avoid fish highest in mercury during pregnancy.

The biggest dilemma is that it is nearly impossible to get enough omega 3s, specifically DHA, while limiting your fish intake to 12 ounces per week. The risk of mercury is only half of the story. In addition to some amount of mercury, fish also contains selenium which reduces the effects of mercury toxicity. There is an argument that the ratio of selenium to mercury is a better determinant of the safety of seafood than just mercury content alone. In addition, there have been some studies done on prenatal, and postnatal consumption of fish at high levels, that have not found a relationship to impaired neurodevelopment. For more in-depth information on eating fish during your pregnancy, you can listen to this episode. It also covers concerns like dioxins, PCBs, and radiation.

Sushi

There are a couple of things to keep in mind when deciding whether it is safe to eat sushi during your pregnancy. The FDA states that if fish are intended for raw or undercooked consumption, they must be properly frozen before they are served. The reason for this is that freezing the fish kills off parasites. This policy does except some shellfish, tuna, and certain farm-raised fish. I had a tough time finding solid information on whether this policy is enforced or monitored. Even frozen fish that do not contain any parasites could contain a bacteria or a virus. This risk can still exist even if the fish was frozen. While this is a risk that is always there, you are at a higher risk during pregnancy because your immune system is suppressed. Plus, if you did get a bacteria or virus from fish it could create some serious complications for your baby. If the fish is cooked then this should not be an issue.

Undercooked Eggs

The same concerns about bacteria contaminating raw or undercooked fish apply to raw or undercooked eggs. The risk of foodborne illness (think food poisoning) is always there but with your baby on the way, you may want to be cautious or avoid it altogether.

Pesticides

Pesticides in your food are another thing you may want to be cautious about. In a clinical report from the American Academy of Pediatrics on organic foods, they note that lower pesticide levels may be significant for children. The risk of pesticides in one of the biggest reasons consumers choose to buy organic. The health benefits of eating fresh fruits and vegetables outweigh the risk of pesticide exposure. Please do not avoid eating fruits and veggies just to avoid pesticides. Children are at higher risk for pesticide toxicity than adults. This is because their developing brain is more susceptible to neurotoxicants. Children also have lower activity and levels of enzymes that are responsible for processing toxins. Prenatal exposure is a concern because when you are pregnant your baby is exposed to everything you are. Plus, your baby is going through critical stages of development in utero.

Research has linked pesticides to ADHD in children, poorer intellectual development, working memory and IQ as a function of prenatal exposure, and structural changes in the developing human brain in children exposed prenatally to specific pesticides.

The Environmental Working Group evaluates 48 fruits and vegetables to monitor pesticide residue. The data used to create EWG’s Shopper’s Guide is from produce tested as it is typically eaten. This means washed and, when applicable, peeled. There are two lists that come from this that data that are useful. The Dirty Dozen is the top 12 foods that rank highest for pesticides. If this is something you want to avoid these are good fruits and veggies to buy organic. The Clean 15  are the 15 fruits and veggies that rank the lowest in pesticide use. The non-organic versions of these fruits and veggies use a low amount of pesticides. Buying these non-organic can be a good strategy to save some money on your groceries.

Genetically Modified Organisms

More than 60 countries around the world require GMO labeling. This includes Australia, Japan, and all of the countries in the European Union.  Unfortunately, this is something that the United States has been slow to adopt. Overall GM crops have decreased the use of insecticides but increased the use of herbicides because many GMO crops are herbicide-tolerant. That means that herbicide can be sprayed directly on crops and kill weeds without killing crops. The foods that are genetically modified are alfalfa, canola 90%, corn 88%, cotton 90%, Hawaiian papaya >50%, soy 94%, sugar beet 95%, yellow summer squash, and zucchini. Animal feed typically contains corn, soy, and alfalfa, which are genetically modified.

If you would like to buy non-GMO you can look for the Non-GMO product verified label, buy organic, or avoid foods with ingredients that are not organic and derived from GM crops.

The Institute for Responsible Technology has a lot of information on GMOs if you want to learn more. As a heads up, this is an organization that is very anti-GMO. The FDA also has consumer information on genetically engineered plants. The FDA states foods from the genetically engineered plant varieties are as safe as comparable, non-GE foods.

For more information on the pros, cons, and research on eating organic during pregnancy see this episode.

Finding Solutions that Work For You

A good strategy in evaluating foods that you need to be cautious about is to weigh the risks and the benefits. Depending on how much you really want that sushi roll, the benefit may outweigh the risk. On the other hand, perhaps you can enjoy a veggie roll just as much without the risk of eating raw fish. You can mitigate your risks of many foods by knowing the source you are getting food from. The concern of food contaminated with bacteria may be lower from a restaurant you have been going to for years.

If you feel like you cannot live without something we covered you should have some good tools to evaluate your risks. If you do decide that you need to limit or cut out something you love, like that morning cup of coffee, I know this seems like an impossible task now. You are only pregnant for 9 months and this period of being cautious about everything you are consuming is short, and it gets easier over time.

Talking to Your Doctor or Midwife

If you have any questions about whether a food or drink is safe please bring it up with your doctor or midwife. Don’t be afraid to ask why something is off-limits. You can also ask what the risks are of consuming it so you can better make an informed choice.

 

Thank you to the amazing companies that have supported this episode.

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