Sole is a healthy, lean white fish that delivers a strong amount of protein with very few calories. A 100-gram serving (about 3.5 ounces) contains roughly 83 calories, nearly 17 grams of protein, and only 1.4 grams of fat. That protein-to-calorie ratio makes it one of the leanest animal protein sources available, and it carries low mercury levels, placing it firmly in the “eat more fish” category for most people.
Nutritional Profile of Sole
Sole’s standout feature is how much protein you get for so few calories. With about 17 grams of protein and just 83 calories per 100-gram serving, roughly 80% of its calories come from protein. That makes it comparable to chicken breast in terms of protein density, but with the added benefits that come from eating seafood.
Where sole really shines is in its micronutrient content. Petrale sole provides about 2.5 micrograms of vitamin B12 per 100 grams, which covers your entire daily requirement. Pacific Dover sole is lower at 0.7 micrograms but still contributes meaningfully. Both varieties are excellent sources of selenium, a mineral that supports thyroid function and acts as an antioxidant. Pacific Dover sole contains a particularly high 91 micrograms per 100 grams, well over the daily recommended 55 micrograms. Phosphorus is also well represented at 162 to 211 milligrams per serving, supporting bone health and energy metabolism.
Omega-3 Content Is Modest
If you’re eating fish primarily for omega-3 fatty acids, sole won’t be your best choice. European sole contains only about 0.1 grams of DHA per 100 grams, with just trace amounts of EPA. Compare that to salmon, which can deliver 1 to 2 grams of combined EPA and DHA in the same serving size. Sole is a leaner fish, and leaner fish naturally carry fewer of these beneficial fats.
That said, sole still contains some omega-3s, which puts it ahead of tilapia. Flounder and sole have a similar texture and mild flavor to tilapia, but tilapia is notably lower in omega-3 content. If you prefer mild white fish and want at least some omega-3 benefit, sole is the better pick. For a serious omega-3 boost, though, you’d want to rotate in fattier fish like salmon, mackerel, or sardines throughout the week.
Mercury Levels Are Low
Sole falls into the flatfish category alongside flounder and plaice, and this group has some of the lowest mercury concentrations of any commercial fish. FDA testing from 1991 to 2009 found an average mercury level of 0.056 parts per million in flatfish, with a maximum recorded level of 0.218 ppm. For context, the FDA’s action level for mercury in fish is 1.0 ppm, meaning sole sits well below the threshold of concern. Pregnant women, nursing mothers, and young children can eat sole without the mercury worries that come with swordfish, shark, or king mackerel.
A Concern for Urban-Sourced Sole
Because sole is a bottom-dwelling fish, it lives in close contact with sediment where industrial pollutants can accumulate. This matters most for sole caught near urban waterways. Monitoring in Puget Sound, for example, found that PCB levels in English sole fillet tissue exceeded human health screening thresholds at every single monitoring site tested. PCB concentrations were highest in fish from urban and near-urban bays, and levels have actually increased at several locations over the past 26 years.
This doesn’t mean all sole is contaminated. Commercially sold sole from open ocean fisheries carries far less risk than sole caught recreationally near industrial harbors or superfund sites. If you’re buying sole from a grocery store or restaurant, it’s generally sourced from regulated commercial fisheries where contamination levels are much lower. The concern applies most to people catching their own sole in polluted coastal waters.
Sole for Weight Management
Sole’s extremely low calorie count and high protein content make it well suited for weight loss or maintenance. Protein is the most satiating macronutrient, and fish protein may offer a subtle edge. One controlled study found that when people ate a fish-based lunch instead of a beef-based lunch with the same calorie and protein content, they ate 11% fewer calories at their evening meal. The participants didn’t report feeling hungrier; they simply chose less food. That kind of passive calorie reduction adds up over time.
A 100-gram fillet of sole gives you a substantial protein serving for fewer calories than virtually any other animal protein. You could eat a generous portion, add vegetables and a grain, and still come in well under 400 calories for a complete meal. For people tracking macros or trying to stay in a calorie deficit without feeling deprived, sole is one of the most efficient options.
How Sole Compares to Other Fish
- Sole vs. salmon: Salmon has far more omega-3s and more calories. Sole wins on leanness; salmon wins on heart-healthy fats. Ideally, eat both.
- Sole vs. tilapia: Similar mild flavor and texture, but sole has more omega-3s and vitamin B12. Tilapia is often cheaper and more widely available.
- Sole vs. cod: Both are lean white fish with similar calorie profiles. Cod fillets tend to be thicker and firmer, while sole is thinner and more delicate. Nutritionally, they’re close.
Fish Allergy Considerations
Sole contains parvalbumin, the protein responsible for most finfish allergies. Research on a Spanish fish-allergic population found that nearly 70% of patients with fish allergy reacted to sole parvalbumin specifically. The study also confirmed high cross-reactivity between parvalbumins in sole, cod, and salmon, meaning if you’re allergic to one of these fish, you’re likely allergic to the others. Fish allergy is different from shellfish allergy, so being allergic to shrimp doesn’t necessarily mean sole is off limits, and vice versa.
Best Ways to Keep It Healthy
Sole’s mild, delicate flavor makes it versatile, but preparation matters. Baking, broiling, steaming, or pan-searing with a small amount of olive oil preserves its low-calorie advantage. Breading and deep-frying a sole fillet can easily triple its calorie count and add inflammatory fats that offset the benefits of eating fish in the first place. A squeeze of lemon, fresh herbs, and a light sear in a hot pan is one of the simplest and healthiest preparations. Because the fillets are thin, they cook in just three to four minutes per side.