Diet and Mental Health

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Recent evidence suggests that good nutrition is essential for our mental health and that a number of mental health conditions may be influenced by dietary factors.

One of the most obvious, yet under-recognised factors in the development of major trends in mental health is the role of nutrition. The body of evidence linking diet and mental health is growing at a rapid pace. As well as its impact on short and long-term mental health, the evidence indicates that food plays an important contributing role in the development, management and prevention of specific mental health problems such as depression, schizophrenia, attention deficit hyperactivity disorder, and Alzheimer’s disease.

Nearly two thirds of those who do not report daily 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. This pattern is similar for fresh vegetables and salad. Those who report some level of mental health problem also eat fewer healthy foods (fresh fruit and vegetables, organic foods and meals made from scratch) and more unhealthy foods (chips and crisps, chocolate, ready meals and takeaways).

A balanced mood and feelings of wellbeing can be protected by ensuring that our diet provides adequate amounts of complex carbohydrates, essential fats, amino acids, vitamins and minerals and water.

While a healthy diet can help recovery, it should sit alongside other treatments recommended by your doctor.

Food consumption

What we are eating now is very different from that of our recent ancestors. Food production and manufacturing techniques, coupled with changing lifestyles and increasing access to processed foods, mean that our intake of fresh, nutritious, local produce is much lower, at the same time as our intake of fat, sugar, alcohol and additives is much higher. It has been estimated that the average person in the UK and other industrialised countries will eat more than 4 kilogrammes of additives every year.

Over the last 60 years there has been a 34% decline in UK vegetable consumption with currently only 13% of men and 15% of women now eating at least five portions of fruit and vegetables per day. People in the UK eat 59% less fish than they did 60 years ago - decreasing the consumption of essential omega-3 fatty acids.

Healthy eating on a budget

A healthy diet can be more expensive. Fish, fruit and vegetables can be particularly pricey. However, by cutting down on sugary drinks and snacks, takeaways and alcohol, you can save money so you can buy healthier foods.

Take care to buy only as much as you know you can use within the next few days, to reduce waste. You can also cut your costs by taking advantage of special promotions and by shopping at market stalls, which are often cheaper than supermarkets. If you live alone you could save money by splitting purchases with friends (buying bulk is usually cheaper) or by cooking several portions of a dish and freezing some of them. This also saves energy and saves you the effort of preparing meals every day.

Frozen fruit and vegetables are often cheaper than fresh produce and are usually just as good nutritionally (with no wastage). Fresh fruit and vegetables are usually cheapest when they are in season. Beans, lentils and soy mince are also cheaper than meat and just as nutritious.

Regular meals

Eat regular meals throughout the day to maintain blood sugar levels.

Make sure you eat at least three meals each day. Missing meals, especially breakfast, leads to low blood sugar and this causes low mood, irritability and fatigue. If you feel hungry between meals you may need to include a healthy snack eg. fruit, nuts and cereals.

Refined foods

East fewer high sugar foods and more wholegrain cereals, nuts, beans, lentils, fruit and vegetables.

Sugary foods are absorbed quickly into the bloodstream. This may cause an initial ‘high’ or surge of energy that soon wears off as the body increases its insulin production, leaving you feeling tired and low.

Wholegrain cereals, pulses, fruit and vegetables are more filling and, because the sugar in these foods is absorbed more slowly, don’t cause mood swings.

These foods are more nutritious as they contain thiamin (B1), a vitamin that has been associated with control of mood, and folate and zinc (supplements of these nutrients have been shown to improve the mood of people with depression in a small number of studies).

Choose:

  • bread – wholemeal and granary rather than white. Also try rye breads, pumpernickel, wholemeal pitta bread, wholemeal chapattis, oat cakes, rice cakes and corn cakes
  • breakfast cereals – choose high fibre, low sugar types eg. wholegrain or bran cereals or porridge
  • rice and pasta – go for Basmati and brown rice (this gives a nutty texture in salads) and wholemeal pasta
  • potatoes – serve boiled new potatoes in their skins (with a little bit of butter) or mashed or jacket potatoes. Potato wedges (lightly brushed with olive oil) are a lower fat alternative to chips and roast potatoes if you are watching your weight. Try sweet potatoes or yams for a change – these are delicious baked.

Aim to eat at least five portions of fruit and vegetables a day eg. 1 glass of orange juice or ½ grapefruit for breakfast, a banana or apple for a mid morning snack, salad at lunch time and then two types of vegetable (a portion is roughly two serving spoons) and piece of fresh or baked fruit for your evening meal.

NB: Green vegetables should be steamed or boiled in a little water and should not be overcooked or you will lose much of the vitamin content.

Avoid sugar and sugary drinks, cakes, sweets and puddings. These are loaded with calories but have little nutritional value and may trigger mood swings because of their sugar content.

Protein in your diet

Include protein at every meal to ensure a continuous supply of the amino acid tryptophan to the brain.

We all need to eat enough protein to maintain our skin, organ, muscle and immune function but recent research suggests that one particular component of protein, the amino acid tryptophan, can influence mood.

Supplements of tryptophan were tested in studies and in some were shown to improve the mood of people with depression. The supplements were not considered safe and were removed from the market. However, you can ensure your brain gets a regular supply of tryptophan by including at least one good sized portion of protein at each meal ie. meat, fish, eggs, milk, cheese, nuts, beans, lentils (dhal), or a meat substitute such as textured vegetable protein or mycoprotein.

NB: Peanuts are low in tryptophan so if you eat them at a meal-time include another source of protein (eg. other nuts) at the same time.

Variety of food

Eat a wide variety of foods to keep your diet interesting and to ensure you obtain all the micronutrients you need.

The more varied your diet, the more likely you are to obtain all the nutrients you need. If you have bread at one meal, try cereal or potatoes, rice or sweet potatoes at the others. Make sure you include at least 2 portions of different fruits and/or vegetables and a protein food at each meal.

Include some red meat and fish, as they are good sources of vitamin B12, another nutrient that seems to be associated with mood. If you are vegetarian or have a limited budget, include fortified soy mince and yeast extract to increase your intake of this vitamin.

Fish in your diet

Include fish, especially oily fish, in your diet.

A few studies suggest that omega 3 oil supplements may reduce symptoms in people with depression on antidepressant medications. These studies are small but we know that a proper balance of omega 3 and omega 6 oils in the diet is important.

To get a good balance of mega 3 and 6 oils:

  • include more omega 3-rich oily fish from sustainable fish stocks – try to include 2–4 portions a week (but no more than 2 portions if you are pregnant or breastfeeding). If buying tinned fish, choose varieties in water, brine or tomato sauce rather than in sunflower oil (this is high in omega 6)
  • if you fry food (eg. stir fries) use an oil high in monounsaturates eg. olive or rapeseed oil
  • choose a monounsaturated margarine or butter for spreading. Avoid margarines or low fat spreads containing omega 6 polyunsaturated or hydrogenated trans fats (trans fats are damaging to your brain and arteries)
  • avoid processed foods such as pies, sausage rolls, crisps and cakes – these are high in saturated and trans fats.

If you don’t like fish you could try an omega 3 supplement (choose one that is purified, contains no vitamin A and has a high eicosapenanoic acid (EPA) content – take no more than 1g EPA per day). If you are vegetarian, try a flax seed supplement (although only a very small fraction of the omega 3 contained in plant products can be used by the body).

Weight

Maintain a healthy weight.

Depression affects different people in different ways. Some people lose interest in food or can’t motivate themselves to shop and cook, so lose weight. Others find they want to eat more and gain weight when they are unhappy. Some medications can also increase or decrease your appetite – if you are concerned that the medication you are taking has made your weight problems worse, speak to your doctor.

Both excessive weight loss or weight gain can make your mood worse and should be avoided. Weight loss and lack of good nutrition will deprive the brain of glucose and the other nutrients that control mood – you may need the advice of a dietitian to help you overcome this problem.

Putting on weight unintentionally or feeling out of control of your eating can increase your depression and can lead to yo-yo dieting, which leaves you further out of control. If you are overweight, follow the advice on healthy eating but be extra careful to limit your fat and sugar intake (no fries, pies, cakes, puddings, sweets, chocolate or sweet drinks), use less fat in cooking, reduce your alcohol consumption, avoid sugary drinks, and increase your exercise levels.

Fluid intake

Maintain adequate fluid intake.

Not drinking enough fluid has significant implications for mental health. The early effects of even mild dehydration can affect our feelings and behaviour.

An adult loses approximately 2.5 litres of water daily through the lungs as water vapour, through the skin as perspiration and through the kidneys as urine. If you don’t drink enough fluids to replace this loss then you will get symptoms of dehydration, including irritability, loss of concentration and reduced mental functioning.

Coffee, colas, some energy drinks and tea all contain caffeine, which some people use to boost energy levels. However, in large quantities caffeine can increase blood pressure, anxiety, depressive symptoms and sleep problems.

Caffeine also has a diuretic effect in the body – it encourages the production of urine and therefore leads to dehydration. For this reason you should not rely solely on caffeine-based fluids.

If you do take drinks with caffeine in them, try to limit yourself to just 3–4 cups per day and drink other fluids such as water, fruit juice and non-stimulant herbal teas at other times. Chocolate also contains caffeine and should be limited to an occasional treat.

Alcohol intake

Limit your alcohol intake.

Alcohol has a depressant effect on the brain and can result in a rapid worsening of your mood. It is also a toxin that has to be deactivated by the liver. During this detoxification process the body uses thiamin, zinc and other nutrients and this can deplete your reserves, especially if your diet is poor.

Thiamin and other vitamin deficiencies are common in heavy drinkers and can cause low mood, irritability and/or aggressive behaviour, as well as more serious and long-term mental health problems.

Because the body uses important nutrients to process alcohol, people who experience depression should consider avoiding alcohol until they have recovered. Even then, because of alcohol’s depressant effects, they should consider drinking only small amounts – no more than once a week.

If you do want to drink alcohol, try not to exceed the recommended safe limits – two units a day for women and three units for men.

1 unit = 1 small glass wine (8 % ABV)
½ pint beer or lager (3.5 % ABV)
1 single measure spirits (40 % ABV)
1 small glass sherry or port (20 % ABV)
 
NB. % ABV is the strength of the alcoholic content. If the % ABV is higher than the examples listed above, then the drink contains more units of alcohol.

Find out more about alcohol and mental health.

Exercise

Exercise regularly

Exercise leads to the release of endorphins – feel-good chemicals in the brain that help us to relax and to feel happy. Exercise is particularly important for people with depression as it also gives structure and purpose to the day. Outdoor exercise that exposes us to sunlight is especially valuable as it affects the pineal gland and directly boosts mood.

Exercise has some other advantages if you are trying to control your weight. For example, the more you exercise, the less you need to cut down on your calorie intake to control your weight. It is also beneficial for heart health and it ensures that you replace fat with muscle, resulting in a more toned body. Exercise also prevents bone mass loss and the increased risk of osteoporosis that can occur if you diet but don’t exercise.

There is no need to join a gym – walking is the easiest, cheapest and best form of exercise and it can be built up as your fitness level increases. Swimming is good for people with joint problems who find weight-bearing exercise difficult. Cycling is also good. Whatever kind of exercise you choose, start with 20 minutes at least three times a week and increase this as your fitness improves.

Find out more about exercise and mental health.

Nutritional supplements

At the moment evidence for the benefits of nutritional supplements is weak, but if you decide to try them:

  • choose a complete one-a-day multivitamin / mineral preparation containing the full recommended daily intake of each vitamin and mineral. These products are relatively safe as they do not contain excessive amounts of any single nutrient (but you should avoid other supplements containing these nutrients, in particular vitamin A as it is toxic in high doses)
  • if your doctor prescribes vitamins or minerals for you, tell him/her about any products you are already taking
  • if you do take a multivitamin supplement, avoid eating liver and other offal products such as pate, as these are also high in vitamin A.

It is important to remember that supplements are not an alternative to a healthy diet and you should still maintain a varied and balanced diet.

Depression and diet 

A number of cross-country and population-based studies have linked the intake of certain nutrients with the reported prevalence of different types of depression. For example, correlations between low intakes of fish by country and high levels of depression among its citizens – and the reverse - have been shown for many types of depression. Complex carbohydrates as well as certain food components such as folic acid, omega-3 fatty acids, selenium and tryptophan are thought to decrease the symptoms of depression.

Those with low intakes of folate, or folic acid, have been found to be significantly more likely to be diagnosed with depression than those with higher intakes. Similar conclusions have been drawn from studies looking at the association of depression with low levels of zinc and vitamins B1, B2 and C. In other studies standard treatments have been supplemented with these micronutrients resulting in greater relief of symptoms in people with depression and bi-polar affective disorder, in some cases by as much as 50%.

Sample meal pattern

Breakfast 1/2 grapefruit / fruit juice

Cereal e.g. wholegrain or bran cereal / porridge, with semi-skimmed milk

or

1–2 slices wholemeal bread / toast with scraping of monounsaturated spread / butter, and kippers / egg / grilled bacon / baked beans

Tea / coffee / herbal tea / water

Mid morning Tea / coffee / herbal tea / water

Fruit / nuts
Lunch 1–2 slices wholemeal or pitta bread sandwich with scraping of monounsaturated spread / butter and filling of fish / meat / egg / cheese / humus / meat substitute / nut butter, with salad

Or jacket potato with baked beans / tuna and corn / chilli con carne / prawn filling, and salad

Or soup e.g. pea and ham / farmhouse broth, and bread

Or salad with meat / fish / egg / cheese, and bread

Or cooked meal – see below

Fruit / yoghurt

Tea / coffee / herbal tea / water
Mid afternoon Tea / coffee / herbal tea / water

Fruit / fruit and nuts / mixed seeds
Dinner 2tblsp Basmati or brown rice / wholemeal chapattis / wholemeal pasta / new potatoes / sweet potato / yam / couscous and 100–120g meat / fish / eggs or bean / lentil dish e.g. chilli con carne / rice and peas / dhal / stir-fried prawns and vegetables and 2 portions of green and root vegetables / large mixed salad

Fresh / tinned fruit / baked fruit and low fat crème fraiche / yoghurt

Tea / coffee / herbal tea / water
Supper Small bowl of cereal, as breakfast, or toast and yeast extract / nut butter / cheese

This advice was written Dr Lynn Harbottle, consultant in nutrition and dietetics at the Health and Social Services Department, Guernsey, sponsored by an educational grant from Nutricia Clinical Care.


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