People who suffer from food allergies generally experience food intolerance, reduced absorption of nutrients, and relief of symptoms after fasting.

Most people think of food allergy symptoms as physical ones  abdominal pain, indigestion, nausea, and vomiting. But mental symptoms can include fatigue, slowed thinking, irritability, agitation, aggressiveness, anxiety, depression, hyperactivity, and learning difficulties.

A study based on a survey of more than 40,000 U.S. adults published in JAMA found that nearly one out of 10 people truly had food allergies, whereas nearly one out of five participants only believed that they were food allergic.

The findings suggest that food allergies are common, but people who suspect they have a food allergy should get appropriate testing to ensure it’s really an allergy causing their physical or mental symptoms.