What Can Happen To Your Body If You Eat Canned Tuna Every Day?

Canned tuna is as reliable as a food can be. This pantry item is a go-to ingredient for countless lunch and dinner recipes, and preparing it for use is as simple as draining the can and tumbling the meat into whichever dish you're making. And cooked canned tuna is so easy and enjoyable to eat that it's little wonder people end up eating it every day — but have you ever asked yourself what happens if you do? Like any food, canned tuna can have an impact on your body if eaten in high enough quantities, and not all of its potential effects are necessarily positive.

One of the main concerns around eating canned tuna is its mercury levels. Like in other types of fish, organic mercury can build up in tuna over time. In turn, this mercury can build up in your body when eaten regularly. This can lead to a range of unpleasant, potentially dangerous symptoms. The sodium content of canned tuna can also be cause for concern, as eating saltier products regularly can start to affect your body in unexpected ways. That's not to say it's all bad news, though. Canned tuna is high in protein and abundant in several essential vitamins and minerals, which can boost your health in various ways. We've got the good and the bad of eating canned tuna on the regular right here.

Canned tuna comes in several varieties, and no matter which one you pick, it provides a hefty dose of protein in one go. A 5-ounce can of drained tuna provides approximately 17 grams of protein, covering a significant proportion of the amount needed per day. All this protein is great news for your muscles, particularly if you're strength training to build strength or mass.

When you eat protein, it breaks down into amino acids. These amino acids are vital for repairing and building muscle tissue, which is broken down when you exercise. If you eat enough protein and sufficient amounts of calories, your muscles will come back bigger and stronger. Tuna is particularly useful for this, as not only does it allow you to quickly boost your protein intake. And, as an animal product, it contains the nine essential amino acids that don't occur in the human body, but which are crucial for building muscle tissue. 

It's worth bearing in mind, though, that you'll likely need more than just one can of tuna a day to do this. According to a 2022 study published in Sports Medicine, aiming for 1.5 grams of protein per kilogram of body weight will help you build muscle optimally.

If your head's starting to feel a little sore, and you can't pinpoint the reason why, check how much tuna you're eating. A headache is a key symptom of mercury poisoning, which can be a consequence of consuming too much tuna on a regular basis. Other symptoms can include irritability and memory loss, which, like a headache, can seem fairly general.

If you're noticing any of these changes, it may be worth remembering that adults are recommended to limit canned tuna consumption to one or two cans a week. Any more than that can start to overload the body with mercury, which can accumulate over time, leading to a host of health concerns. Crucially, the type of canned tuna you're choosing may also have an effect on your mercury levels. Skipjack tuna tends to be lowest in mercury, as it's younger than other tuna types and so has less time to build up levels of the toxic metal. Albacore tuna tends to have higher mercury levels. Skipjack and albacore can also vary widely, with some albacore varieties having way more mercury than others. It's always important to check your product's label for its mercury content.

You've probably heard how important omega-3 fats are for your health, but you may be less familiar with all of their effects. Most of us know that omega-3s are good for our heart, for example, but what about our brains? Luckily, they have a positive impact on our thinking organ too — particularly when it comes to age and stress-related diseases like Alzheimer's. One 2023 study published in Biomolecules found that individuals who were more predisposed to developing Alzheimer's due to greater stress exposure could be more protected if they consume more omega-3s.

As for where you get those omega-3s — well, you'll be pleased to hear that they're abundant in canned tuna, and eating it every day could top up your intake considerably. Just four ounces of albacore or white tuna could provide you with between 500 and 1,000 milligrams of omega-3s. This covers the daily amount recommended for healthy adults, and goes a long way towards the recommended amount for those with coronary heart disease. Skipjack tuna provides a slightly lower amount, but will still deliver between 250 and 500 milligrams of these key fatty acids.

It's vital to keep an eye on your blood pressure and follow a healthy diet that doesn't contain too much sodium. However, one unassuming ingredient — tuna — could be providing you with more sodium than you think. A humble 5-ounce can of tuna can have 370 milligrams of sodium in it, which covers 16% of the 2,300 milligrams recommended in the daily value. While 16% may not sound like a lot, when you consider that you're likely to combine your tuna with other salty ingredients like mayonnaise, sliced dill pickles, or even cheese, opting for a can every day can have a significant impact on your sodium intake.

These small choices can create big problems. Sodium raises blood pressure by causing your blood vessels to contain more fluid, which then puts a strain on said vessels and your entire cardiovascular system, which can lead to a higher risk of chronic diseases. While high blood pressure isn't just caused by high sodium intake, it's a key factor, and reducing it can be an important step in protecting your health.

Crucially, too, not all types of canned tuna are high in sodium, and there are some low-sodium options out there. Consuming these occasionally may actually have a heart-protective effect and help lower blood pressure, thanks to the combination of low-sodium and omega-3 fatty acids. However, you should keep the saltier options on the shelves.

How often do you think about how your food affects your bone health? Usually, the association between our diets and our skeletons starts and ends with milk, but other foods like tuna can play a key role in protecting our bones. Canned tuna is surprisingly high in vitamin D, with 100 grams of canned light tuna containing 269 International Units of vitamin D (in layman's terms, that's a lot — roughly a third of the amount you need every day). Vitamin D is one of the key nutrients you need for bone health, and getting sufficient amounts from your food can help you protect against diseases like osteoporosis. Importantly, though, you'll need to combine this with vitamin D from sunlight, and certain people may also need to supplement with the vitamin.

It's not just the vitamin D in tuna that helps, either. Tuna's protein content can also assist in strengthening your bones, and getting enough protein is important at pretty much any stage in your life to keep your skeleton robust and prevent osteoporosis. Adults should aim for a minimum of 46 to 56 grams of protein per day, with women aiming for the former number and men aiming for the latter.

It can often feel like we can't control our eye health, and if we develop the need for glasses or contact lenses then that's just a result of genetics. However, our vision can be affected by multiple factors, including our diet — and eating canned tuna every day could have a protective effect. This is thanks to the omega-3s that are so abundant in canned tuna, which have been observed to be beneficial to the eyes. In a review of studies published in the Current Opinion in Pharmacology journal, the potential positive effects of consuming fish rich in omega-3s were discussed, particularly for the ability of these types of fish to protect against age-related macular degeneration. The review's authors recommended that those at risk of developing the disease should include more fatty fish in their diets.

Omega-3s have also been observed as being potentially helpful for dry eyes, which can result in blurred vision and eye pain. Additionally, the omega-3s in tuna aren't the only thing that's helping your vision. Vitamin D has also been found to be protective for eye health, and it's pretty abundant in canned tuna. Together, these two wonder nutrients could keep your peepers feeling pretty healthy.

It's probably no surprise that eating food gives you energy — but the type of food you eat can have a big effect on the quality of the energy you receive from your grub. Unlike other foods — which can leave you with a burst of energy and feeling sluggish afterward — eating canned tuna can offer you a sustained feeling of energy, particularly when combined with other ingredients. Whether you buy or make your own canned tuna, the food is high in protein, and pairing this protein with healthy fats and carbs will keep your energy levels balanced, preventing your blood from being flooded with sugar and causing an energy spike.

Certain nutrients within the tuna itself can also contribute to better energy levels. Tuna is full of iron, a vital nutrient that ensures the proper transfer of oxygen around the body via the bloodstream. This process keeps you properly energized and able to perform your daily activities with ease. Tuna is also high in vitamin B6, which plays an essential role in helping carbs convert to glucose, which keeps you energized. Try piling some healthy tuna salad onto a slice of whole wheat bread for a quick snack that combines protein, fat, complex carbs, and tons of energizing nutrients.

What we eat can have a huge effect on our mood. The more lacking in key nutrients our diet is, the more likely we are to experience low moods. This can be exacerbated by making dietary choices that prioritize foods like refined carbohydrates, which are not only low in vitamins and minerals, but can cause our blood sugar to spike and crash — crashing our mood as it does so.

Luckily, eating canned tuna every day can help bolster your nutritional intake, and therefore your mood. Its vitamin D content is particularly valuable here. Getting enough vitamin D has been consistently associated with better overall moods, as well as better mental health outcomes. One meta-analysis of studies published in the Journal of Affective Disorders found that consuming adequate levels of vitamin D unequivocally has a positive effect on symptoms of depression in adults. Getting enough vitamin B6, which canned tuna has a good amount of, may also help to improve your mood and prevent depression. A 2008 study published in the Journal of the American College of Nutrition found that lower levels of vitamin B6 in elderly adults seemed to correlate with higher rates of depression.

Eating something as innocent-seeming as a can of tuna can have some pretty profound effects, due to its mercury levels. While symptoms like headaches or irritability may not seem that serious, they're the thin end of the wedge for some way more dangerous consequences, particularly to your organs. Especially high levels of mercury can start to damage your kidneys, leading to kidney disease and the death of certain kidney cells, according to a 2022 study published in Kidney International Reports. As the body's filtration system, your kidneys' job is to remove the waste from your body – but this makes them particularly susceptible to damage from toxic heavy metals like mercury.

It's worth pointing out that this is less likely to happen in the short term. The kidneys really start to be affected when mercury levels are high in the bloodstream, and it can take time for these levels to build up. Eating a can of tuna every day for a week is less likely to cause long-lasting damage. Importantly, though, mercury can come from other types of seafood and in some beverages and can be present in foods that contain high fructose corn syrup. All of these things can combine to boost your mercury intake even further — and your daily tuna could tip things over the edge.

Tuna's high-protein content is useful for lots of things — building your muscles, keeping your bones strong, and helping to produce hormones – but one of the most noticeable effects it has is on your hunger levels. Protein helps to satisfy hunger, thanks to a combination of controlling your hunger hormones and taking longer to digest than other types of food. A 2006 study published in the Journal of the American College of Nutrition showed that eating high-protein meals can reduce the production of ghrelin, the hormone that prompts you to feel hungry. Meanwhile, the complex structure of protein causes it to sit in your stomach longer as it breaks down, keeping you satisfied for longer.

To really increase your tuna's ability to keep hunger at bay, try combining it with a high-fiber component. Like protein, fiber takes longer to digest than foods like simple carbs, and it moves through your gut more slowly. Instead of putting your tuna salad on some white flour-based crackers, mix it with beans or serve it on a dense rye bread. Alternatively, you could make an avocado tuna salad, as the avocado will provide both fiber and healthy fats.

On the surface, eating canned tuna when you're pregnant can seem like a good idea. It's nutritious and a great source of protein, and it's definitely hassle-free — ideal for when you're tired and just want to get your feet up. However, eating it every day when pregnant is definitely not advised, due to the potential impact it can have on your unborn baby. When you eat canned tuna, its mercury content goes straight into your bloodstream. This bloodstream is, of course, shared with your unborn baby, and higher levels of mercury can cause developmental issues.

You should also consider lowering your tuna intake if you're breastfeeding, as the mercury in it can pass through your breast milk to your infant. Luckily, you don't have to cut tuna out entirely, either if you're pregnant or breastfeeding. You should instead stick to the guidelines that are suggested for most people. Try to eat no more than three servings of canned light tuna per week, or no more than one serving of canned albacore tuna. If you have any concerns about whether your tuna intake is affecting your baby, speak to your doctor.

If you've been getting more colds than you usually do, it might be worth considering your diet. A healthy overall diet contributes to a stronger immune system, and while adding a daily can of tuna won't necessarily revamp your entire immunity, it can contribute important vitamins that keep you healthy. One such vitamin is vitamin D, which comes in high quantities in fish. Research published in the journal Nutrients claimed that "the evidence of a link between vitamin D deficiency and adverse outcomes" when it comes to immunity is highly established, and points to the presence of vitamin D receptors on virtually every cell in the immune system, speaking to its importance for good health.

Tuna's protein content is also important for good immune function. When you have enough protein in your diet, your body is able to make antibodies more effectively, which helps to prevent infection. The vitamin B6 in tuna can also help boost your immune system and make your body more capable of warding off illness. As with any food, though, tuna should just be part of a diet composed of diverse whole food sources, to give your body the best chance of building a strong immune system.

Canned tuna's benefits for your skin aren't something that's talked about that often. Adding it to your diet, though, could give your skin health a serious boost, thanks to several different nutrients in it. Tuna's vitamin B6 levels can be especially helpful for healthy skin, and the Handbook of Diet, Nutrition and the Skin has flagged that low levels of B6 in the diet can be a factor in dermatitis, a condition defined by skin inflammation. The same study, however, also points out that getting too much B6 can have a negative effect, as it makes skin more prone to sun damage.

The omega-3 fatty acids in tuna may also improve your skin health. These fats' anti-inflammatory effects may be especially useful in combating acne, which the Journal of Clinical and Aesthetic Dermatology points out is primarily an inflammatory disease. For the best results, combine tuna with other unexpected ingredients that have anti-inflammatory properties to keep your skin looking good.