These 4 Healthy Foods Can Actually Be Harmful

Canned tuna recipes
Photo Credit: Coley Cooks

January 28, 2021

By Isadora Baum

Usually we try to eat enough healthy foods, filling our plates with plenty of fruits and vegetables, lean proteins, and healthy fats. But it turns out you really can get too much of a good thing. Here are four healthy foods that are actually harmful if you eat them in excess.

1. Brazil Nuts

There’s a reason why you’ll only find one or two of these big guys in a handful of mixed nuts. Chicago-based registered dietician Rachelle LaCroix Mallik notes that while Brazil nuts are a great source of selenium, critical for production of thyroid hormone, too many can bring on selenosis, an overdose of the mineral, which can cause hair loss, fatigue and gastrointestinal problems.

“Brazil nuts contain on average 68 to 91 mcg per nut and the tolerable Upper Limit (UL) for adults is 400 mcg. That means eating just five Brazil nuts daily could put you above the recommended maximum amount of selenium intake,” Mallik says.

She recommends eating no more than 2 or 3 per day, while also watching intake from other foods such as yellowfin tuna, beef and liver.

2. Carrots

A diet rich in vitamin A and beta-carotene (a pigment that converts to vitamin A) improves eye health, fights free radicals, protects against sun damage, and boosts overall immunity. But eating too many carrots can have a slight “skin-yellowing” effect, turning your nose, palms, and/or the soles of your feet a yellow-orange color, Mallik warns.

The same applies to other vitamin A- and beta carotene-rich foods like cantaloupe and sweet potatoes, and to foods that are contain lycopene (which also converts to vitamin A). These include watermelon, tomatoes, and grapefruit.

The skin-yellowing effect isn’t toxic, and you can reverse it by simply reducing your intake of the foods that cause it, but if you notice other symptoms like dizziness, bone pain, and impaired vision, see a doctor immediately, Mallik says.

The UL for adults is 10,000 IU vitamin A, or one medium-sized carrot, so it’s important to keep an eye on what you’re getting from food and supplements. Pregnant women should be extra-careful, because too-high levels of vitamin A can increase risk of complications.

3. Cinnamon

Cinnamon adds tons of flavor and comes with plenty of health benefits, but portions matter. “Regular cinnamon (Cassia) has a large amount of a compound called coumarin, which can be toxic in large doses,” says NYC-based clinical cardiologist Dr. Luiza Petre.

Sprinkling here and there is perfectly fine as long as you keep it to no more than about a teaspoon per day.

4. Canned Tuna

There’s a reason why canned tuna is a pantry staple; it’s an affordable and convenient way to get in heart-healthy omega 3 fats and protein — that is, so long as you choose the right kind of tuna.

Some types of tuna contain more mercury than others; too much mercury can damage the central nervous system, leading to symptoms such as irritability, fatigue, behavioral changes, tremors, headaches and more.

White albacore tuna contains 4 to 5 times the mercury of light tuna, notes Dr. Partha Nandi, host of the TV show “Ask Dr. Nandi.” When buying light tuna, look for skipjack, a type that is lower in mercury than other varieties, he adds. He also recommends tuna packed in water, since it has more omega-3 fatty acids than tuna packed in oil. Another option: Canned wild salmon. It’s lower in toxins, high in omega-3s and just as convenient as tuna.

“The upper limit of safety is 0.1 micrograms per kilogram of weight,” Petre says. “This means that a 110-lb. adult could only eat one 5-oz. serving of canned white tuna every 19 days. Any more exceeds the recommended upper limit.” Nandi recommends that pregnant women steer clear of canned tuna altogether, as the mercury content can be dangerous for fetal development.