The question
My teenage daughter is anxious about returning to school. Can certain foods cause anxiety and others calm you down?
The answer
After a stress-free summer, heading back to the classroom – or the office – can create feelings of anxiety in many of us. And your diet may be partly to blame. Studies suggest certain foods can make you feel calmer while others can aggravate anxiety.
Components in foods such as carbohydrates, vitamins, minerals, antioxidants and even probiotic bacteria are thought to influence mood. Some are used to manufacture calming brain chemicals while others help regulate how the brain responds to stress.
While diet won't cure anxiety, eating a steady fare of nutritious and well-balanced meals and snacks may help improve your mood. Use the following quick guide on what to eat – and what to avoid – to help lessen anxiety.
Swiss chard
This leafy green is packed with magnesium, a mineral that helps the body respond to stress. In mice, a magnesium deficiency has been shown to trigger anxiety and studies in people suggest the nutrient has anti-anxiety effects.
One cup of cooked Swiss chard delivers 150 mg of magnesium, along with one-third of a day's requirement of vitamin C, a nutrient that helps reduce the physical and psychological effects of stress. Adults older than 30 need 420 mg (men) and 320 mg (women) of magnesium a day. Sauté Swiss chard in olive oil with garlic and red chili flakes. Add steamed Swiss chard to omelettes and frittatas. Stir Swiss chard leaves into pasta sauces and soups near the end of cooking.
Other magnesium-rich foods: almonds, cashews, spinach, kale, tofu, black beans, kidney beans and yogurt.
Brown rice
This high-carbohydrate whole-grain food helps deliver tryptophan to your brain, an amino acid that's used to synthesize a feel-good brain chemical called serotonin. Serotonin plays an important role in mood, anxiety and happiness.
Eating a high-carbohydrate meal increases the amount of tryptophan that enters the brain, whereas a high-protein meal decreases it. High-protein foods such as meat, fish and poultry supply other amino acids that compete with tryptophan to cross the blood-brain barrier.
Brown rice also has a low glycemic index (GI) value, meaning it doesn't cause a sharp rise in blood sugar (glucose) and insulin. High glycemic foods that spike glucose and insulin – e.g. refined grains and sugar – can cause premature low blood glucose and hunger. Blood-sugar crashes and hunger can cause anxiety symptoms.
Include low-GI, carbohydrate-rich foods at all meals and snacks. Other low-GI foods: steel-cut oats, sweet potato, barley, bran cereals, whole-grain pumpernickel bread, quinoa, legumes and most types of fruit.
Bananas
Our body needs vitamin B6 to synthesize serotonin and bananas are an exceptional source, supplying one-third of a day's worth (0.5 mg each). Adults ages 19 to 50 need 1.3 mg per day; older adults require 1.7 mg (men) and 1.5 mg (women) daily.
And, contrary to popular belief, bananas have a low glycemic index, so they don't spike your blood sugar and insulin.
Other outstanding sources of B6: turkey, wild salmon, baked potato (with skin), avocado, spinach and fortified breakfast cereals.
Kefir
A study of 710 college students, published in the June issue of Psychiatry Research, found that eating more fermented foods, such as kefir, was linked to fewer symptoms of social anxiety. (Social anxiety is characterized by intense nervousness and self-consciousness that arises from a fear of being closely watched and judged by others.)
Drinking kefir, rich in probiotic bacteria, helps promote a healthy balance of gut bacteria, which evidence strongly suggests contributes to normal mood.
In lab animals, probiotics have been shown to reduce anxiety- and depression-like behaviours and prevent increases in cortisol (a stress hormone).
Drink kefir, pour it over cereal and granola or blend it with fruit to make a smoothie. To reduce added sugars, choose a brand that is unflavoured.
Other fermented foods that deliver probiotics: kimchi, unpasteurized sauerkraut and natto.
Green tea
Preliminary research has shown that taking a green tea extract for seven days reduced stress and increased calmness in healthy individuals. The researchers used an extract that provided 300 mg of EGCG, a potent antioxidant in green tea leaves.
According an analysis of 24 brands of green tea conducted by the independent laboratory ConsumerLab.com, one cup of brewed green tea contains 25 mg to 86 mg of EGCG. The longer you steep your tea, the more antioxidants you'll get.
Green tea (and black and white teas) also contains L-theanine, an amino acid shown to reduce anxiety by increasing brain levels of dopamine and GABA, neuro-transmitters involved in mood and relaxation.
What to limit or avoid
While coffee (caffeinated) helps some people feel more alert and focused, drinking too much can cause others to feel jittery and nervous.
In people predisposed to anxiety disorders, caffeine can trigger a racing heart and sweaty palms and lead to a panic attack. (Green tea is considerably lower in caffeine than coffee.)
Alcohol, too, can make anxiety worse by changing levels of serotonin and other neurotransmitters in the brain.
Everyone feels nervous or anxious from time to time – for example, when speaking in public, working to meet a deadline or taking a test – but for some people constant anxiety interferes with their lives.
If your daughter regularly experiences excessive worry, irrational fears, sleep disturbances, indigestion or muscle tension, signs of a possible anxiety disorder, consult with your doctor.
While dietary adjustments may make some difference to her mood, they are not a replacement for treatment.
Leslie Beck, a registered dietitian, is based at the Medisys clinic in Toronto.
Leslie Beck