Tuna is not a high-calcium food. A typical 3-ounce serving of tuna provides roughly 10 to 15 milligrams of calcium, which is about 1% of the 1,000 milligrams most adults need daily. If you’re looking to boost your calcium intake, tuna alone won’t make a meaningful dent.
That said, tuna does have a nutritional trait that indirectly supports calcium: it contains vitamin D, which your body needs to absorb calcium from other foods in the same meal. So while tuna isn’t a calcium source worth counting on, it can play a supporting role in your overall bone health.
How Tuna Compares to Calcium-Rich Foods
To put tuna’s calcium content in perspective, consider what actually qualifies as “high in calcium.” An 8-ounce glass of milk delivers about 300 milligrams. A cup of cooked kale provides around 180 milligrams. Three ounces of canned sardines (with bones) offer roughly 325 milligrams. Tuna’s 10 to 15 milligrams per serving is a fraction of these amounts.
Canned tuna with bones can contain slightly more calcium than boneless varieties, since the tiny softened bones are edible and add mineral content. But even then, the increase is modest compared to sardines or canned salmon with bones, which are among the best fish sources of calcium.
Tuna’s Vitamin D Advantage
Where tuna does contribute to bone health is through its vitamin D content. About 100 grams of baked tuna contains 3.1 micrograms of vitamin D. Your body requires vitamin D to absorb calcium efficiently from everything else you eat. Without enough vitamin D, you can consume plenty of calcium-rich foods and still fall short because your intestines won’t take it up properly.
Pairing tuna with calcium-rich sides, like a salad with leafy greens or a meal that includes cheese, takes advantage of this relationship. The vitamin D from the tuna helps your body make better use of the calcium from those other foods.
Daily Calcium Targets by Age
Most adults between 19 and 50 need 1,000 milligrams of calcium per day. Women over 51 and all adults over 70 need 1,200 milligrams. These numbers include everything from food and supplements combined.
Reaching 1,000 milligrams requires deliberate food choices. A rough strategy: three servings of dairy (milk, yogurt, or cheese) throughout the day gets most people close. If you don’t eat dairy, fortified plant milks, tofu made with calcium sulfate, and leafy greens like bok choy and broccoli are reliable alternatives. Tuna can be part of a healthy diet, but it shouldn’t be counted toward your calcium goal in any meaningful way.
Mercury Limits for Tuna
If you enjoy tuna for its other benefits (protein, vitamin D, omega-3s in some varieties), mercury is the main factor limiting how much you should eat. The FDA categorizes different types of tuna by mercury level:
- Best choice (lowest mercury): Canned light tuna, including skipjack. You can safely eat two to three servings per week.
- Good choice (moderate mercury): Albacore (white) tuna, canned or fresh, and yellowfin tuna. Limit these to one serving per week.
- Avoid: Bigeye tuna, which has the highest mercury levels of any commonly sold tuna.
A standard serving is about 4 ounces, roughly the size of your palm. For pregnant or breastfeeding women, the same palm-sized portion applies, and sticking to the “best choice” category is especially important.
Better Fish Sources of Calcium
If you specifically want fish that contributes calcium, look for varieties where you eat the bones. Canned sardines and canned salmon are the standouts because the canning process softens the bones enough to eat and digest. A 3-ounce serving of canned sardines provides over 300 milligrams of calcium, more than 20 times what tuna offers. Canned salmon with bones delivers around 180 to 200 milligrams per serving.
These fish also provide vitamin D, giving you both the calcium and the nutrient needed to absorb it in a single food. If bone health is your primary concern and you like seafood, sardines and bone-in canned salmon are far more efficient choices than tuna.