These large seeds are crazy high in the antioxidant mineral selenium. Just one nut contains your daily dose. The problem? Too much selenium is toxic, and may cause symptoms such as loss of hair and nails, diarrhea, skin rashes, mottled teeth, and nervous system abnormalities. That's why you often see separate bulk containers of almonds, pecans or walnuts, but not usually for Brazil nuts.
Instead: Stick with mixed nuts. Grab a handful and eat a variety of nuts, but don't pick out and only eat a dozen Brazil nuts.
A scoop of tuna is an easy sandwich option, and raw tuna is common among sushi lovers. In fact, canned tuna is the second-most frequently eaten seafood after shrimp in the United States — that's great since it's a lean source of protein, and is high in heart-healthy omega-3 fats.
The issue is that albacore tuna (the second-most commonly eaten type, after skipjack) is a very large fish, and spends a lot of time in mercury-laden waters. Methylmercury builds up in tuna, and if you eat too many servings per week, it can build up in your body, too, and interfere with the brain and nervous system. Mercury toxicity can cause memory loss, vision loss or trouble regulating blood pressure levels. High mercury intake is especially problematic in children, women of childbearing age, and women who are pregnant or breast-feeding, because mercury affects the development of a child's brain and nervous system. These groups should limit albacore tuna intake to no more than once a week.
Instead: Smaller species of tuna, including skipjack and yellowfin, have less mercury than albacore or bigeye tuna. When choosing canned tuna, look for "light" instead of "white" fish, and choose yellowfin instead of bigeye for your sushi and sashimi. "Ahi" may refer to yellowfin or bigeye, so sushi lovers should ask which species they are getting.
If you have a small sprinkle of cinnamon on your oatmeal or chai tea latte, you have nothing to worry about. It adds a delightful flavor. Some research has shown that cinnamon may help lower blood sugar — at doses of a teaspoon or more per day. The trouble is that grocery store cinnamon, a spice known as cassia cinnamon, contains a compound called coumarin, which has been linked to an increased risk of liver disease when consumed in excess (more than a teaspoon per day).