As with everything, too much of anything is bad. Variety is good for your body. Eating only tuna and avocado won’t give you all the nutrients you need to fully nourish your body.
First, change up what you eat. It’s healthier for you.
This image is from the USDA’s My Pyramid initiative. It shows you that your body needs more than what you’re giving it right now.
Also, the mercury level in tuna can add up to be harmful. It also depends on the type of tuna you’re eating.
There are two main kinds of canned tuna: chunk light and solid or chunk white (albacore). Most canned white tuna is albacore. Its mercury levels are almost three times higher than the smaller skipjack, used in most canned light tuna.
These recommendations are based on EPA guidance and estimates of mercury in the most popular canned tunas:
Canned white, or albacore (0.32 parts per million of mercury). Children under six can eat up to one 3-ounce portion a month; children from 6–12, two 4.5-ounce portions a month. Adults, including pregnant women, can safely eat it up to three times a month (women, 6-ounce portions; men, 8-ounce portions).
Canned light — the safer choice (0.12 parts per million of mercury). Children under six can eat up to three 3-ounce portions per month. Older children and adults can safely eat it once a week. But look out for “gourmet” or “tonno” labels. They are made with bigger yellowfin tuna and can contain mercury levels comparable to canned white.
A better alternative is canned salmon (mostly sockeye or pink from Alaska), which is low in contaminants and high in heart-healthy omega-3s. It’s also sustainably caught in Alaska and similarly priced, making it a great choice all around.
And why is mercury so bad you ask? Part of it is where it comes from:
Air pollution. Specifically, it rains down on rivers, lakes and oceans after being emitted from power plants and other industrial sources that burn fossil fuels.