Lunch may be the most lackluster meal of the day. However, it’s not just the lack of options at the salad bar that might be giving people the blues but rather the excess copper consumed when they choose greens for lunch every day. Leafy greens, cashews, chickpeas, avocado and shellfish are naturally high in copper, and according to health experts, consuming too much of these food items could lead to feelings of anxiousness and depression.

After investigating patients who had been complaining about feelings of anxiety, exhaustion, trouble with focusing and overall mental funk, Dr. Svetlana Kogan, internist and author of "Diet No More," discovered copper toxicity, a condition caused by too much copper intake, was to blame.

Although Kogan told the CBS affiliate in New York on Tuesday that “copper is an essential element” that helps promote normal growth and health, “if somebody is consuming excess they could certainly be at risk” for copper toxicity. Kogan blamed increased vegetable-based diets and eating fads for the copper overload.

“If you look for example at coconut and how big of a fad it's become, it's easy to see how it can contribute to copper toxicity,” she said. “There's coconut water, coconut oil, coconut chips. I love coconut and eat it, too. But taking it to the extreme could be dangerous.”

Environmental exposure through copper-coated water pipes could also cause copper toxicity.

Diagnosing copper toxicity is no easy feat because the condition is often only spotted through tissue or blood and urine samples.

However, treating the condition isn’t as complicated. The internist said copper toxicity can be easily treated by merely sweating out the toxins. Kogan recommended for those suffering from copper toxicity to hit the sauna and start following a well-balance diet. Swapping out foods high in copper for items that are naturally rich in zinc also goes a long way in defeating copper toxicity, she said.