Tuna is a nutritious and protein-rich saltwater fish that can contain high levels of mercury. As a result, regular tuna consumption may lead to health issues.
Volcanic eruptions and industrial activity emit mercury into the oceans, where it builds up in marine life. This article reviews mercury in tuna and tells you whether it’s safe to eat this fish.
Tuna contains more mercury than other popular seafood items, including salmon, oysters, lobster, scallops and tilapia (1).
This is because tuna feed on smaller fish which are already contaminated with varying amounts of mercury. Since mercury is not easily excreted, it builds up in the tissues of tuna over time (2, 3).
Ahi tuna also known as yellowfin tuna is a popular fish used in dishes like sushi and poke bowls. It’s loved for its rich, meaty texture and mild flavor. However, some people worry about mercury contamination in tuna. So how much ahi tuna can you safely eat?
Ahi Tuna Nutrition
Ahi tuna is an excellent source of protein, vitamins, and minerals. A 3-ounce serving contains
- Protein: 22 grams
- Selenium: 78% of the Daily Value (DV)
- Vitamin B12: 105% of the DV
- Vitamin B6: 18% of the DV
- Niacin: 43% of the DV
- Magnesium: 19% of the DV
- Potassium: 5% of the DV
It also provides omega-3 fatty acids, which are linked to heart health and brain function.
However, ahi tuna is high in mercury because it’s a large, predatory fish. Mercury builds up in the tissues of fish that eat other contaminated fish.
Mercury in Tuna
Mercury is a heavy metal found in the environment. When ingested at high levels, it acts as a neurotoxin, meaning it can damage the brain and nervous system.
Fetuses, infants, and young children are most vulnerable to mercury’s toxic effects, which can harm brain development.
For this reason, the FDA provides guidelines on how much tuna is safe to eat for pregnant women, women who may become pregnant, nursing mothers, and young children.
Ahi Tuna Consumption Recommendations
For Pregnant Women, Women Who May Become Pregnant, & Nursing Mothers
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Do not eat ahi tuna. Avoid all forms, including canned, fresh, and frozen.
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Eat up to 12 ounces (2 average meals) of low-mercury fish per week. Good choices are salmon, shrimp, pollock, tilapia, catfish, and cod.
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Avoid high-mercury fish like swordfish, shark, king mackerel, and tilefish.
For Children Ages 1–11 Years Old
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Eat up to 4 ounces (1 average meal) of low-mercury canned light tuna per week OR up to 4 ounces of mild white tuna steaks per month.
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Avoid ahi tuna and all high-mercury fish.
For Adults & Children Over 12 Years Old
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Eat up to 6 ounces (1 average meal) of ahi tuna per week.
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For canned light tuna, up to 12 ounces is considered safe per week.
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Check local fish advisories for limits on locally caught fish. Some may have higher contaminants.
Note that a typical serving or meal size of fish is about 3–6 ounces when cooked. Consuming more than the recommended amounts regularly could lead to mercury buildup over time.
Tips to Limit Mercury Exposure from Tuna
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Choose the right tuna — canned light tuna and skipjack tuna are safer than ahi or albacore tuna.
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Eat more low-mercury fish like salmon, shrimp, tilapia, and cod.
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Vary your protein sources — swap seafood for beans, eggs, chicken, etc.
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Check advisories for locally caught fish in lakes and rivers, which may be more contaminated.
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If eating tuna steaks, choose smaller sizes under 6 ounces. Larger tuna concentrate more mercury.
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Grill, broil, or bake tuna instead of frying. The cooking method affects mercury levels.
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Avoid frequent tuna sushi meals, as raw fish retains all its mercury.
The Bottom Line
Ahi tuna is very high in mercury, so it should be avoided completely by pregnant women and limited by children under 12 and adults. Canned light tuna and other low-mercury fish are safer options.
By following the FDA’s guidelines on fish consumption and mercury, you can incorporate tuna safely as part of an overall healthy, balanced diet. Focus on moderation of high-mercury fish while emphasizing low-mercury varieties for optimal health.
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Levels in Different Species
Levels of mercury in fish are measured either in parts per million (ppm) or micrograms (mcg). Here are some common tuna species and their mercury concentrations (1):
| Species | Mercury in ppm | Mercury (in mcg) per 3 ounces (85 grams) |
| Light tuna (canned) | 0.126 | 10.71 |
| Skipjack tuna (fresh or frozen) | 0.144 | 12.24 |
| Albacore tuna (canned) | 0.350 | 29.75 |
| Yellowfin tuna (fresh or frozen) | 0.354 | 30.09 |
| Albacore tuna (fresh or frozen) | 0.358 | 30.43 |
| Bigeye tuna (fresh or frozen) | 0.689 | 58.57 |
Is Canned Tuna Safe To Eat? Experts Weigh In On The Benefits Of Eating The Canned Fish | TIME
FAQ
Can you eat Ahi Tuna every day?
How often can you eat raw Ahi Tuna?
Is Ahi Tuna high in mercury?
How much is too much tuna to eat?
How often should you eat ahi tuna in Hawaii?
The Hawaii State Department of Health recommends limiting your servings to twice per month. Ahi tuna comes loaded with protein. Each 6-ounce serving of tuna offers an impressive 41.5 grams of protein — 90 percent of the daily protein needs for women and 74 percent for men, according to the U.S. Department of Agriculture.
How much tuna should one consume per week for health?
The answer to this question depends on many individual factors such as your weight, age, physical activity factor, and how your diet is in general, since tuna is rich in proteins and fats, and an excess of it can also cause damage to health.
Is ahi tuna good for You?
Ahi tuna is a good source of nutrients good for your health like protein, vitamin D and potassium. Learn more about how to add ahi tuna into your diet.
Is it safe to eat tuna every day?
Tuna is one of the most convenient protein sources that exists, so it can easily become a go-to lunch. But is it safe to eat it every day? Nearly all seafood contains traces of mercury, according to the Food and Drug Administration. So the question is: At what level does mercury become poisonous? Tim Boyle / Today The short answer: Probably.