Question: I understand that a healthy diet can help with the treatment of depression, but does diet have any impact on anxiety? I have been diagnosed with a generalised anxiety disorder.
Answer: The cost-of-living crisis along with the global pandemic have given many people plenty to worry about. Yet even before the pandemic began, researchers had identified a substantial increase in general anxiety in recent decades. Rates of anxiety and depression globally climbed a further 25% in the first year of the Covid-19 outbreak, according to the World Health Organisation. And the 2022 Southern Cross Healthy Futures Report, which surveyed more than 5000 New Zealanders, found cost-of-living stress was affecting both physical and mental health, including by disrupting sleep and exercise.
Anxiety disorders are marked by excessive worry, to the point it is counterproductive, and affect physical, emotional and social functioning. Many forms exist: generalised anxiety, social anxiety, panic disorders, agoraphobia, separation anxiety disorders and more. Generalised anxiety disorder is defined in the Lancet as “a persistent and common disorder in which the patient has unfocused worry and anxiety that is not connected to recent stressful events, although it can be aggravated by certain situations”.
Observational research has long linked healthier diets, such as the Mediterranean one, to better mental health. But observational studies cannot prove that the diet caused the better mental health – they only show an association between the two.
However, in recent years, the links between diet quality and mental health have garnered a lot more interest, noted a 2020 article in the British Medical Journal. In particular, the “Supporting the modification of lifestyle in lowered emotional states” (Smiles) trial, conducted in Australia and published in 2017, was a significant step forward in the field of diet and mental health. This 12-week randomised controlled trial involved 67 adults who were diagnosed with major depression. Most also had clinical levels of anxiety. Roughly half were allocated to a “diet support” group and 25 to a “social support” control group.
The study found clear evidence that a healthier Mediterranean diet improved mental wellbeing and symptoms of major depression. Although its key focus was the effect of diet on depression, secondary objectives included assessing how diet altered symptoms of anxiety. And the researchers found a Mediterranean diet also reduced anxiety, leading them to conclude that the benefits of dietary improvements could extend to the “management of common comorbidities” of depression, which include conditions such as anxiety.
So there is every reason to suspect that adopting a Mediterranean-style diet may reduce symptoms of anxiety, alongside therapies such as medication, counselling and other lifestyle changes including stress-reduction techniques.
After the 12-week study, the dietary support group had significantly improved their daily diet, consuming 1.2 more servings of whole-grain cereals, 0.46 more servings of fruit, 0.52 of dairy, 0.42 of olive oil, 1.4 of pulses and 1.12 a week of fish. They also reduced their intake of less-nutritious “extra” foods by a whopping 21.76 servings a week. In contrast, no significant dietary changes occurred for these food groups among the control group.
New Zealanders have tended to have an excessive intake of so-called “discretionary foods” that are nutrient poor and high in saturated fat, salt or added sugar. Over 25% of our energy intake came from extras such as non-alcoholic beverages (5%), alcoholic beverages (4.9%), sugar and sweets (4.2%), cakes and muffins (3.7%), biscuits (2.7%), pies and pasties (2.5%), snack bars and foods (1.3%), and puddings and desserts (1%), according to the most recent New Zealand Adult Nutrition Survey in 2008-09. And that doesn’t include our fast-food intake.
On that basis, dietary improvements that reduce intake of discretionary foods and increase intake of wholefoods such as vegetables, fruits and whole grains are likely to be an accessible and effective treatment option for anxiety as well as depression, alongside standard pharmacological and psychological treatments. Thus, there is nothing to lose and potentially much to gain by adopting a Mediterranean-style diet.
The Smiles Trial diet
The diet group were tasked with consuming:
- Whole grains: 5-8 servings per day
- Vegetables: 6 servings per day
- Fruit: 3 servings per day
- Legumes: 3-4 servings per week
- Dairy (low-fat and unsweetened): 2-3 servings per day
- Nuts, raw and unsalted: 1 serving per day
- Fish: at least 2 servings per week
- Lean red meats: 3-4 servings per week
- Chicken: 2-3 servings per week
- Eggs: up to 6 per week
- Olive oil: 3 tablespoons a day
Limits:
Intake of “extra” foods such as sweets, refined cereals, fried food, fast food, processed meats and sugary drinks was limited to no more than 3 per week.
Up to 2 standard drinks of red or white wine per day were allowed, but all other alcohol (eg, spirits, beer) was considered “extras”.
