The intrinsic link between nutrition and physical health has long been accepted, but what about mental wellbeing? Industrialised food production has devalued the nutritional benefit of many foods, and it’s not just our bodies that pay the price. Depression, concentration and memory problems are just some of the detrimental side-effects, as Catherine Sleep reports.

As they strive to eat the recommended five portions of fruit and vegetables a day, or cut sugar intake, consumers tend to think of the boost this will give their physical health, and indeed this is the angle that most health advisers and authorities promote. Few, however, concentrate on the mental health implications of our daily diet.

In the UK, for example, the National Health Service (NHS) recently launched its “Just Eat More (fruit and veg)” campaign by touting the following benefits of fruit and veg: they can help you to maintain a healthy weight, they’re an excellent source of fibre and antioxidants and they help reduce the risk of heart disease and some cancers. Similarly, the US government’s primary nutrition website,, talks about the benefits of a healthy diet in terms of reduced risk of stroke and other cardiovascular diseases, as well as type 2 diabetes and cancers, and last but most certainly not least, weight control.

German nutrition society DGE (Deutsche Gesellschaft für Ernährung) arguably comes closest to addressing the impact of diet on mental health when it recommends that people consciously take time to enjoy their meals. The society emphasises that slow, deliberate eating is key to good nutrition, adding that unhurried, careful meal-taking encourages variety and helps people feel satisfied without overeating. But even the DGE still steers shy of linking specific ingredients or food production methods with long-term mental health.

High price to pay

Mental ill-health costs the UK alone almost £100bn (US$175.6bn) per year and causes untold suffering to hundreds of thousands of people. It’s on the increase too, and mental health problems are now the number one reason for people to claim Incapacity Benefit.

New research released today (16 January) by the Mental Health Foundation (MHF) and Sustain suggests that food can have an effect upon a person’s mental health and behaviour that is both immediate and lasting because of the way it affects the structure and function of the brain. The MHF report finds that some foods damage the brain by releasing toxins or oxidants that harm healthy brain cells, while an unbalanced diet that fails to include adequate amounts of complex carbohydrates, essential fats, amino acids, vitamins and minerals and water can prevent people achieving a balanced mood and feelings of wellbeing.

Much evidence of a link between food and behaviour and mood has hitherto been anecdotal, with teachers and prison staff for example reporting improved concentration and performance among schoolchildren given breakfast or inmates fed diets supplemented with vitamins, minerals and essential fatty acids. However, the new research suggests that changes to the human diet over the last 50 years or so are an important factor behind the significant rise in mental ill health.

Additive overload, fat imbalance

The last half-century has witnessed remarkable alterations to what food we eat, how we process and refine what we eat, food additives, the use of pesticides and the alteration of animal fats through intensive farming. It has been estimated that the average person in the UK and other industrialised countries will eat more than four kilogrammes of additives each year.

Changing methods of farming have also introduced higher levels and different types of fat into our diet. To take one example, chickens now reach their slaughter weight twice as fast as they did 30 years ago, which has changed the nutritional profile of the meat. Whereas a chicken carcass used to be 2% fat, it is now 22%. Also, the diet fed to chickens has changed dramatically, which has reduced omega-3 fatty acids and increased omega-6 fatty acids in chicken meat. Similarly, the diet fed to farmed fish is changing the ratio of fatty acids in the fish we eat. The recent and widespread appearance of trans fats (hydrogenated vegetable oils) in the diet raises concern too.

This is significant in that the fats we eat directly affect the structure and substance of the brain cell membranes. Essential fatty acids omega-3 and –6 make up 20% of the fat in our brain, and must be derived from our diet as the body cannot make them itself. Unequal intakes of the two different types of fat are implicated in mental health problems, with experts suggesting that the Western diet now includes too much omega-6 and insufficient omega-3.

Social behaviour towards food was also scrutinised by the researchers. They found that nearly two thirds of those who do not report mental health problems eat fresh fruit or fruit juice every day, compared with less than half of those who do report daily mental health problems, with this pattern repeated for fresh vegetables and salad. Young people are highlighted as a particularly vulnerable group, with just 29% of 15-24 year-olds eating a meal made from scratch every day, compared with 50% of those aged over 65.

Food for mental health

In the light of these and other findings outlined in the Feeding Minds report, Dr Andrew McCulloch, CEO of the Mental Health Foundation, called for further investigations into the role that dietary interventions might play in alleviating or preventing mental health problems. He said that diet needs to become a cornerstone of an integrated approach to mental ill-health that encompasses biological, psychological, social and environmental factors.

The report specifies 14 key recommendations aimed at a range of government departments and other stakeholders such as the Food Standards Agency, the Department of Health, Social Services and Public Safety, the School Food Trust, NHS Health Boards, Mental Health Trusts and the Home Office (with regard to the food offering and culture in the prison service). They encompass specific proposals, for example that access to free water dispensers should be available to all school children by 2007, and that practical food skills such as cooking and growing should be reintroduced as a compulsory part of the national curriculum.

The recommendations also call for agricultural policy to be informed by what is known of its nutritional impact and its subsequent effect on our mental as well as physical health. Support should be increased for organic farming, the production and promotion of fruit and vegetables, other micro-nutrient rich food and for alternative sources to oily fish of omega-3 fats.

None of these changes can happen overnight, but given the growing burden of mental ill health in the UK and other industrialised nations, taking steps to change dietary habits and even food production methods and policies could be a cost-effective approach.