by Dr Sarah Dash

If you look at the menu at your local café, you’ll likely notice a range of options for your meal; gluten-free, low-carb, Paleo friendly. Based on a recent CSIRO report, Australians are electing to avoid certain foods more than ever, and approximately one in three Australians are eliminating gluten, dairy or meat from their diets. While many report that food avoidance is driven by unpleasant symptoms or a desire to improve overall health, eliminating major food groups may leave us worse off.

Restriction vs. moderation – evidence for a varied diet

The popularity of Paleo, grain-free, and low-carbohydrate diets has seen foods such as dairy, grains, legumes, or even certain vegetables rise to the top of the list of foods to avoid.

This advice can be confusing. Popular messages suggest that swapping the meat-and-potatoes our grandparents grew up on with modern alternatives can improve our energy, appearance, and overall health.

Unfortunately, few of these claims have been supported by scientific evidence, and many go against current nutrition science. For example, for those without formally-diagnosed allergies, opting for ‘free-from’ options offers little to no nutritional advantage. When we remove certain foods from our diet, we replace them with others, many of which have been highly processed, and often contain added fats or sugars – a dietary pattern we know is a risk factor not only for physical but also for mental disorders.

By excluding whole grains, legumes, or high quality red meat from our daily diet, we may miss out on a beneficial mix of nutrients (i.e. antioxidants, fibre, zinc), which have been associated with mental health benefits, longevity, and the and the prevention of disease. While theoretically, we may be able to replace them with nutritious alternatives that improve the quality of our diet, very few of us are meeting the minimum dietary recommendations. When we include foods from each food group, we gain a wider range of nutritional benefits from a variety of food combinations – a benefit to both our gut bugs and brains.

A healthy diet across the lifespan and food as nourishment

While diet quality is important throughout life, there are certain life stages where it is particularly key. For example, adolescence is an important time in establishing lifelong healthy habits, and messages of restrictive eating can have long term negative impact. The nutrition status of women of childbearing age is also particularly relevant, as nutrition status during pregnancy and early life lays the foundation for healthy development. Given that women in this age range are most likely to avoid certain foods, it’s important that evidence-based nutrition advice is clearly disseminated among these groups.

The consequences of excluding major food groups are not merely physical; classifying foods as ‘good’ and ‘bad’ has a psychological impact on our approach to food. When we restrict, eating may be associated with feelings of guilt or anxiety, rather than enjoyment or nourishment. As researchers, clinicians and educators, we can highlight the benefits of ‘adding in’ to our diet (vegetables, fibre, legumes, good fats), rather than restricting.

So what should we be eating?

Certainly, for those with severe allergies, avoiding foods that make us sick or cause discomfort is essential. We are still learning a great deal about individualised nutrition, and researchers at the Food and Mood Centre are currently working to understand some of the relationships between food sensitivity and mental health.

However, for much of the healthy population, the public health message remains clear: eating a balanced diet of whole foods is preferable to dietary restriction, and a whole-food dietary pattern has been associated with the prevention and treatment of both physical and mental disorders. Of course, there’s no disputing that reducing our intake of highly processed, discretionary foods offers significant benefits for our individual and global health. Removing poor-quality food from our diet leaves room in our bellies and on our plates for more nutritious options.

The promise of improved health by avoiding certain foods is appealing: many of us are aware that our lifestyle behaviours are related to our physical and mental health, and the proposal of a simple solution is enticing. However, popular nutrition trends change quickly, and the evidence for a balanced, varied, whole food diet has stood the test of time, and importantly, scientific investigation.

Diet is complex, and there’s no quick-fix or restrictive diet likely to revolutionise our health. When it comes to fuelling our bodies and brains, we are better off including a bit of everything, rather than eating to a formula.

Dr Sarah Dash is a founding member of the Food and Mood Centre team and also a Post Doctoral Research Fellow at the Baker Institute in Metabolic and Vascular Physiology

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