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4 Surprising Side Effects of Eating Sardines

Each tiny fish packs a lot of flavor and nutrition—but there is one potential drawback.
FACT CHECKED BY Samantha Boesch

You either love them or hate them—but there's no denying that sardines pack a lot of flavor and nutrition in each tiny fish. These small silver fish come canned in water, oil, mustard sauce, hot sauce, and several other flavorings. Sardines are packed whole, unlike canned tuna or salmon, as each fish is less than 25 centimeters and can be eaten skin, bones, and all.

Don't let their appearance fool you—if you enjoy other "fishy" fish like salmon or herring, you'll probably love sardines' taste. They're a fantastic spread on crackers, piled on toast, tossed in a salad, or stuffed into peppers. And these are just a few of the many ways to enjoy them!

Sardines also bring a lot of nutrition to the table at a low price point. One can (3.75 ounces) of sardines has 22 grams of protein and can be found for as low as $1.50 or less a can.

These tiny fish have loads of flavor and are a versatile, budget-friendly add to your grocery cart, but how healthy are they? Here are four ways eating sardines could affect your health.

They can improve your bone health.

canned sardines in tomato sauce

Sardines naturally have two key nutrients to help keep your bones strong as you age. Since the bones in sardines are so small and soft, they're left in the fish, which is great news for your own bones. "Sardines with the bones are a great source of non-dairy calcium, which is essential for bone health," says Anya Rosen, MS, RD, LD, INFCP, CPT, a virtual functional medicine practitioner based in New York City.

One can of sardines has 27% of the Daily Value (DV) for calcium—more than a cup of milk! Like us, most of the calcium in sardines is stored in their bones.

But, calcium isn't the only way sardines help keep your bones strong and healthy—they're also a great source of vitamin D. Vitamin D is a fat-soluble vitamin that your body needs to absorb calcium. If you're low in vitamin D, the calcium you eat can't do its job protecting your bone strength and integrity.

Oily fish such as salmon, mackerel, swordfish, and sardines are excellent natural sources of vitamin D. One can of sardines has 22% of your DV.

Related: #1 Supplement for Strong Bones After 50, Says Dietitian

They may protect your heart.


Sardines are a convenient way to sneak in your omega-3 fatty acids, as each can has 1 gram of the heart-protecting unsaturated fat. "A diet rich in omega-3 fatty acids has many potential benefits, including lower cholesterol, lower levels of inflammation, and lower risk of developing heart disease," says Bethany Keith MS, RDN, LD, CNSC, registered dietitian at Sizzling Nutrition.

In a 2021 JAMA Internal Medicine review, researchers analyzed data from almost 200,000 adults (with and without heart disease). They found that eating at least 2 servings (175 grams) of oily fish per week significantly lowered the risk of major heart disease in healthy adults and mortality in those who already had heart disease.

They could cause a gout flare-up.

canned sardines and fork

"A high intake of sardines might contribute to flare-ups among gout sufferers, and some varieties of canned sardines can have a high sodium content," says Emma Laing, PhD, RDN, a national spokesperson for the Academy of Nutrition and Dietetics.

Gout is a particularly painful form of arthritis. Flare-ups can be felt as shooting pain, burning, and tenderness in joints like the big toe, ankle, or knee. One cause of a gout flare-up is eating a diet high in purines—a natural substance that breaks down into uric acid in the body. Gout attacks occur when uric acid crystals build up in the joints, causing intense inflammation and pain.

Sardines, anchovies, mussels, trout, and red meat are all high in purines. This doesn't mean you can't eat sardines, but you may need to be cautious of how much you eat and the rest of your diet as well. If you have gout, talk to your doctor or dietitian as you may need to limit your intake of sardines or adjust your overall eating pattern to fit them in, suggests Laing.

They'll give you an energy boost.

grilled sardines on plate with lemon wedge

Along with calcium, vitamin D, omega-3 fatty acids, and protein, sardines are an excellent source of vitamin B12. One can of sardines has 343% of your DV for vitamin B12.

Deficiency in this water-soluble vitamin is most often seen in older adults, those with pernicious anemia (a disease that prevents the stomach from absorbing B12), people with various stomach diseases, and vegetarians or vegans. Not enough vitamin B12 can lead to fatigue, shortness of breath, and low energy.

While the vitamin B12 in sardines won't give you an instant energy boost like caffeine will, including them and other B12 sources and high-quality proteins in your diet will help you feel more energized on a regular basis.

Kelsey Kunik, RDN
Kelsey Kunik is a registered dietitian, freelance writer, nutrition consultant, and sustainable food blogger. Read more about Kelsey