Sole is generally considered a low-mercury fish, and it is safe to eat during pregnancy when cooked thoroughly. The FDA and EPA place flatfish like sole and flounder in the “Best Choices” category for seafood, which includes fish with the lowest mercury levels. This means you can eat two to three servings per week without exceeding recommended mercury limits.
What Is Sole and Where Does It Fit in the Mercury Chart?
Sole is a flatfish that lives on the ocean floor. It is a white, mild-tasting fish that is popular because it cooks quickly and has a delicate texture. Common types include Dover sole, lemon sole, and Petrale sole.
Mercury accumulates in fish as they age and eat smaller fish. Larger predatory fish like shark, swordfish, and king mackerel build up the most mercury. Smaller fish that eat plankton and tiny organisms tend to have much lower levels.
Sole is a small-to-medium fish with a short lifespan compared to predators. It does not spend enough time accumulating mercury to reach high levels. This is why it appears on the “Best Choices” list rather than the “Choices to Avoid” list.
How Much Mercury Is Actually in Sole?
The FDA monitors mercury levels in commercial fish sold in the United States. Their data shows that flatfish, including sole and flounder, have an average mercury concentration of about 0.05 to 0.10 parts per million.
To put that in perspective, the FDA action level for mercury in commercial fish is 1.0 part per million. Fish above that level can be pulled from the market. Sole sits far below that threshold.
Compare sole to high-mercury fish:
- Shark: around 0.98 ppm
- Swordfish: around 0.97 ppm
- King mackerel: around 0.73 ppm
- Tilefish (Gulf of Mexico): around 1.45 ppm
- Sole/flounder: around 0.05–0.10 ppm
These numbers come from FDA sampling data collected over years of testing. The difference between sole and high-mercury fish is substantial — often tenfold or more.
What Are the Official Guidelines for Eating Sole While Pregnant?
The FDA and EPA jointly publish advice for pregnant women about eating fish. Their guidance divides fish into three categories: Best Choices, Good Choices, and Choices to Avoid.
Sole falls into the Best Choices category. This is the same group that includes salmon, shrimp, pollock, tilapia, catfish, and canned light tuna. The recommendation for Best Choices fish is two to three servings per week.
A serving size is about 4 ounces, or roughly the size of the palm of your hand. For a 4-ounce cooked portion, this works out to 8 to 12 ounces of sole per week.
This guidance applies to everyone, but it is especially important for pregnant women because mercury can cross the placenta and affect a developing baby’s nervous system.
Why Does Mercury Matter More During Pregnancy?
Mercury in fish exists primarily as methylmercury, a form that the body absorbs easily. When a pregnant woman eats fish containing methylmercury, it enters her bloodstream and can pass through the placenta to the fetus.
The fetal brain is developing rapidly, especially during the first and second trimesters. Methylmercury can interfere with neuron formation and migration. High levels of exposure have been linked to cognitive delays, attention problems, and motor skill issues in children.
This is why public health agencies set conservative limits. The goal is not to eliminate fish from the diet — fish provides protein, omega-3 fatty acids, iron, and other nutrients that support fetal development — but to choose fish that give you those benefits without the mercury risk.
It is worth noting that the benefits of eating low-mercury fish during pregnancy generally outweigh the risks. Several large studies have found that children of mothers who ate fish during pregnancy had better cognitive outcomes than children of mothers who avoided fish entirely. The key is choosing the right fish.
Is There Any Situation Where Sole Is Unsafe During Pregnancy?
Mercury is not the only concern with fish during pregnancy. Foodborne illness is another risk, and it deserves attention.
Raw or undercooked fish can carry bacteria, viruses, or parasites. Listeria is the most concerning because it can cause serious complications in pregnancy, including miscarriage or preterm labor. Pregnant women are about ten times more likely to get listeriosis than the general population.
Sole is safe when cooked to an internal temperature of 145°F, which is when the flesh turns opaque and flakes easily with a fork. Avoid raw preparations like ceviche, sushi, or sashimi made from sole during pregnancy.
Smoked fish is a separate category. Refrigerated smoked fish, such as lox or nova style, is not safe during pregnancy unless it is cooked to 165°F. Canned or shelf-stable smoked fish is safe because the canning process kills bacteria.
If you are buying sole from a fish counter, ask whether it has been previously frozen. Freezing kills parasites, but it does not kill bacteria. Proper cooking remains the most reliable safety step.
How Does Sole Compare to Other Popular Fish for Pregnancy?
Many pregnant women wonder how sole stacks up against other fish they enjoy. Here is a practical comparison based on FDA mercury data:
| Fish | Mercury Level | Pregnancy Recommendation |
|---|---|---|
| Sole | Low | 2–3 servings per week |
| Salmon | Low | 2–3 servings per week |
| Shrimp | Low | 2–3 servings per week |
| Canned light tuna | Low | 2–3 servings per week |
| Albacore tuna | Medium | 1 serving per week |
| Halibut | Medium | 1 serving per week |
| Swordfish | High | Avoid |
Sole is one of the safest fish choices you can make during pregnancy. Its mercury level is comparable to salmon and shrimp, which are widely recommended by obstetricians and nutritionists.
What About Sole From Different Regions or Farmed Sole?
Mercury levels in sole can vary slightly depending on where it was caught and what it ate. However, the variation is small. All commercially sold sole in the United States falls well within the low-mercury range.
Farmed sole is less common than farmed salmon or tilapia. When it is available, farmed sole is raised on controlled diets, which can actually result in lower mercury exposure than wild-caught fish. The concern with farmed fish is more about environmental contaminants like PCBs, but levels in sole are low across the board.
If you are choosing between wild and farmed sole, either is a safe option during pregnancy. The more important factor is how it is cooked and stored.
What Are the Best Ways to Cook Sole During Pregnancy?
Sole is a delicate fish that does not need heavy preparation. Pan-searing, baking, broiling, and poaching all work well. The key is reaching that 145°F internal temperature.
Baking sole with lemon and herbs is simple and safe. Pan-searing in a small amount of oil until the fish flakes is also fine. Avoid deep-frying, which adds unnecessary calories and can mask whether the fish is fully cooked.
Leftover cooked sole should be refrigerated within two hours and eaten within three to four days. Reheat it until it is steaming hot before eating.
Frequently Asked Questions
Can I eat sole every day while pregnant?
Eating sole daily is not necessary and may not be the best approach. Stick to the recommended two to three servings per week of low-mercury fish, and vary your protein sources.
Is sole safer than salmon during pregnancy?
Both sole and salmon are in the same low-mercury category and are equally safe during pregnancy. Salmon has the added benefit of higher omega-3 fatty acids, which support fetal brain development.
Can I eat sole sushi while pregnant?
No. Raw sole sushi is not safe during pregnancy because of the risk of foodborne illness. Cook sole to 145°F before eating.
Does frozen sole have the same mercury level as fresh sole?
Yes. Freezing does not change mercury content. Frozen sole carries the same low-mercury profile as fresh sole, as long as it is thawed and cooked properly.
