*3.4. Carbohydrates*

One trend that was observed among the carbohydrate studies was a relationship between higher intake of simple or refined carbohydrates, higher glycemic index diet, or sugar intake, and higher levels of anxiety (Figure 7). This association was reported by several animal and observational studies. Similarly, 75% of the 12 animal studies and the only human experimental trial assessing the impact of artificial sweeteners (aspartame, saccharin, and sorbitol) reported an increase in anxiety symptoms. One observational study reported on the relationship between fiber and anxiety; at long term follow up two to three years after completing a program aimed at increasing fiber intake, 14 irritable bowel syndrome patients reported lower anxiety symptoms [31].

**Figure 7.** Studies assessing dietary carbohydrates and anxiety. ■ Higher intake or levels associated with decreased anxiety. ■ No association between intake or levels and anxiety. ■ Higher intake or levels associated with increased anxiety.

Very limited research has been undertaken in the form of human experimental studies that sought to reduce carbohydrate intake (*n* = 4); none included participants with anxiety disorders. Of four studies, one study involving obese or overweight participants reported an improvement in anxiety symptoms following a low carbohydrate diet. Eight studies evaluated the effect of consuming sweetened drinks on anxiety in humans. These studies administered carbohydrate-rich drinks to patients undergoing surgical procedures and measured the immediate effects on anxiety symptom severity, often in comparison with pre-operative fasting. The findings of these studies were mixed.
