Tuna is a popular pantry staple prized for its high protein content, affordability, and versatility. However, with different species and packing methods available, it can be confusing to know which option is best for your health. Making an informed choice involves understanding the nutritional trade-offs, particularly regarding mercury levels and beneficial omega-3 fatty acids.
The Mercury Dilemma: Understanding the Risk
Mercury is a heavy metal found naturally in the environment that can accumulate in fish. As larger fish consume smaller fish, mercury concentrations build up in their bodies. This process, known as bioaccumulation, means larger, longer-living species of tuna tend to have higher mercury levels. Excessive exposure to mercury can be toxic, particularly affecting the nervous system, which is a significant concern for pregnant women, young children, and those who eat large amounts of fish.
Albacore vs. Light (Skipjack) Tuna
Most canned tuna is either albacore or light tuna, which typically comes from the skipjack species. The primary difference lies in the size of the fish and, consequently, their mercury content. Albacore is a larger, longer-living fish, resulting in a higher mercury concentration than the smaller, more rapidly maturing skipjack.
Beyond mercury, these two types of tuna differ in flavor, texture, and other nutritional aspects:
- Albacore (White) Tuna: This variety has a firmer, whiter flesh and a milder flavor. While it is higher in mercury, it also contains more heart-healthy omega-3 fatty acids per serving compared to light tuna.
- Light (Skipjack) Tuna: This type has a darker, softer flesh and a more pronounced 'fishy' flavor. It is the safer choice for regular consumption due to its significantly lower mercury content.
Nutritional Comparison: Albacore vs. Light Tuna (Water-Packed)
| Nutrient (per 3 oz) | Canned Albacore Tuna (Water-Packed) | Canned Light Tuna (Water-Packed) |
|---|---|---|
| Mercury Content | Higher | Lower |
| Omega-3s | ~0.7 g | ~0.2 g |
| Calories | ~109 kcal | ~73 kcal |
| Protein | ~20 g | ~17 g |
| Fat | ~2.5 g | ~0.8 g |
The Best Way to Pack Your Tuna: Water vs. Oil
The liquid in which tuna is packed also impacts its nutritional profile. Water-packed tuna generally has fewer calories and less fat than oil-packed tuna. For those watching their weight or fat intake, water-packed is the better choice. Conversely, if you want a richer flavor and aren't concerned about the extra calories, oil-packed tuna may be preferred. The type of oil used also matters; some brands use heart-healthy olive oil, while others use vegetable oil.
A Deeper Dive into Healthy Choices
To further refine your selection, consider these additional factors:
Look for "Pole-and-Line Caught" or "Troll-Caught" Labels
These terms indicate a more sustainable fishing method that uses individual lines and hooks rather than large, indiscriminate nets. This approach reduces bycatch and is more environmentally friendly. Some high-quality brands are certified for their sustainable practices by organizations like the Marine Stewardship Council (MSC).
Be Aware of Added Sodium
Canned tuna can contain a high amount of sodium, which is a concern for individuals with high blood pressure or those on a sodium-restricted diet. Many brands offer “no salt added” or “low sodium” varieties, which are a healthier choice.
Consider Brands That Test for Mercury
Some companies, like Safe Catch, specifically test each individual tuna for mercury content, adhering to stricter limits than the FDA. Other brands, like Wild Planet and American Tuna, also emphasize sustainability and lower mercury levels through their sourcing practices.
Recommended Consumption Guidelines
For most adults, the FDA recommends consuming 8 to 12 ounces of fish per week. This can include a few servings of low-mercury options like canned light (skipjack) tuna. Higher-mercury varieties like canned albacore should be limited to about one 4-ounce serving per week. Pregnant or breastfeeding women and young children should adhere to stricter guidelines to minimize mercury exposure.
Conclusion: The Final Verdict
Ultimately, the healthiest tuna is the one that best fits your individual needs and consumption habits. For the safest, most regular consumption, canned light (skipjack) tuna packed in water is the best choice due to its low mercury and calorie content. If you eat tuna less frequently and want a higher dose of omega-3s, water-packed albacore can be a good option in moderation. Always look for sustainable sourcing labels and check for low-sodium varieties to make the most informed decision.
The Takeaway
Remember that while mercury is a valid concern, the nutritional benefits of including fish like tuna in your diet are significant. Choosing lower-mercury types and practicing moderation allows you to enjoy its benefits safely.
For more information on fish consumption, including FDA guidelines, visit the FDA's advice on eating fish.
