๐ Mercury Levels & Health Comparison: Salmon vs. Sardines
Mercury Content
- Both sardines and salmon are considered lowโmercury fish, largely because they are small, shortโlived species that eat plankton rather than accumulating mercury through the food chain Livestrong.com+2Wikipedia+2Leigh Torres+2.
- Typical mercury levels:
- Canned sardines: around 0.015โฏppm (parts per million) Leigh Torres+1Dr. Berg+1
- Fresh/frozen salmon: about 0.034โฏppm, and canned salmon even lower at ~0.021โฏppm Wikipedia
Nutritional Benefits
- Sardines are powerhouse sources of omega-3 fatty acids: approximately 2โฏg of DHA + EPA per 3โฏoz serving, along with calcium and vitaminโฏD foodstruct.com+10health.clevelandclinic.org+10sweetishhill.com+10.
- Salmon also provides high-quality omega-3s, good protein, and vitaminโฏD, though per serving omega-3 content is typically lower than sardinesโroughly 400โ700โฏmg per 56โฏg serving versus sardinesโ 1,600โ1,800โฏmg per 85โฏg serving consumerlab.com.
Summary Table
| Fish | Mercury (ppm) | Omegaโ3s (DHA+EPA) | Additional Nutrients |
|---|---|---|---|
| Sardines | ~0.015 ppm | ~1,600โ1,800โฏmg | Calcium, VitaminโฏD, B vitamins |
| Salmon | ~0.021โ0.034 ppm | ~400โ700โฏmg | Highโquality protein; VitaminโฏD, Bโs |
Health Considerations
- Both are excellent low-mercury seafood choices recommended even for pregnant or nursing individualsโthe FDA and other authorities consistently list them among the safest fish Wikipedia+8Wikipedia+8Leigh Torres+8Livestrong.comconsumerlab.com.
- ConsumerLab testing found that while most canned salmon and sardines are low in mercury, some canned sardine products had elevated arsenic levels; so itโs worth checking brand-specific info if available consumerlab.com.
โ Bottom Line
- Neither salmon nor sardines carry high mercury risk.
- Sardines generally have lower mercury and higher omega-3 content per serving compared to salmon.
- Salmon, however, remains a nutritious, low-mercury option with its own benefits.
๐ Why Big Fish = More Mercury
Mercury builds up in fish through a process called bioaccumulation. Here’s what happens:
- Tiny organisms absorb mercury from polluted water.
- Small fish eat those organisms and accumulate mercury.
- Big fish eat lots of small fishโso they absorb even more mercury.
๐ The longer a fish lives and the bigger it is, the more mercury it likely has.
๐ซ High-Mercury Fish to Avoid
These fish are near the top of the food chain and tend to have the highest mercury levels:
| Fish | Avg. Mercury (ppm) | Why Avoid? |
|---|---|---|
| Shark | 0.979 ppm | Apex predatorโvery high mercury |
| Swordfish | 0.995 ppm | Among the highest mercury levels |
| King mackerel | 0.730 ppm | Large species, unsafe for pregnant women |
| Tilefish (Gulf of Mexico) | 1.123 ppm | Extremely high mercury |
| Bigeye Tuna (Ahi) | 0.689 ppm | Not to be confused with skipjack or light |
| Marlin | 0.485 ppm | Large predatory fish |
| Orange Roughy | 0.571 ppm | Long-living deep-sea fish |
๐ง These are especially dangerous for children, pregnant women, and nursing mothers, due to risk of neurological harm from methylmercury.
โ Best Low-Mercury Fish (Eat Often)
These are small, fast-growing, and naturally low in mercury:
| Fish | Avg. Mercury (ppm) | Bonus Nutrients |
|---|---|---|
| Sardines | 0.015 ppm | Omega-3s, calcium, vitamin D |
| Salmon | 0.021โ0.034 ppm | Protein, omega-3s, vitamin D |
| Anchovies | 0.017 ppm | Omega-3s, iron |
| Herring | 0.084 ppm | Vitamin B12, selenium |
| Tilapia | 0.013 ppm | Low-fat protein, selenium |
| Trout | 0.071 ppm | Omega-3s, vitamin B6 |
| Mussels/Clams/Oysters | <0.025 ppm | Iron, B12, zinc, and copper |
๐ง Pro Tip: Wild-Caught vs. Farmed
- Wild-caught salmon usually has slightly more mercury than farmed but often more omega-3s and fewer contaminants like PCBs.
- Farmed fish may be lower in mercury but risk exposure to other toxins depending on farming practices.
๐ Rule of Thumb
โThe smaller the fish, the safer the dish.โ
Big fish live longer and eat lots of small fish, giving them more time to accumulate mercury and other toxins. Small fish like sardines, anchovies, and herring are safer, healthier, and more sustainable choices.