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Understanding the importance to health of a balanced diet

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VOL: 101, ISSUE: 01, PAGE NO: 30

Susan Price, MSc, BSc, AdvDipDietetics, is deputy head nutrition and dietetics, University Hospital Birmingham NHS Foundation Trust, Selly Oak Hospital

With reports of obesity trebling since the 1980s and 22 per cent of men and 23.5 per cent of women now defined as obese (body mass index >30kg/m2) (Department of Health, 2004a), obesity is one of the fastest developing public health problems. Helping people manage their weight and eat a healthy, balanced diet is vital.

The government has addressed the issue of a healthy lifestyle in Choosing Health: Making Healthier Choices Easier (DoH, 2004b). The key issues include measures to tackle obesity and encourage choosing a healthy, balanced diet. The British Dietetic Association has welcomed this report as it recognises the vital role nutrition plays in maintaining health and well-being (BDA, 2004).

Why is a healthy diet important?

The general population needs to have a balanced, healthy diet as it provides the energy and nutrients required to survive and stay healthy. Combining a healthy diet with an active lifestyle has huge benefits and helps reduce the risk of heart disease, cancer and obesity.

Food can be classified as:

- Macronutrients - protein, fats, carbohydrates - provide energy and are essential for growth and maintenance;

- Micronutrients - vitamins, minerals, trace elements - are needed in very small amounts yet are essential for growth and development;

- Phytochemicals - bioactive compounds found in foods such as fruit, vegetables, pulses - have a wide range of beneficial effects on health;

- Water - used to replenish the body’s essential fluid requirements - about 60 per cent of the body is water.

If a person’s diet does not meet their needs eventually they will become unwell. This could be due to an excess of a macronutrient, for example excess fat will lead to obesity, or from a deficiency in a micronutrient, for example a low iron intake will lead to anaemia.

What is a healthy diet?

There is international consensus on what constitutes a healthy diet and the DoH recommendations for a healthy diet Eight Guidelines for a Healthy Diet: A Guide for Nutrition Educators (DoH, 1997) are based on sound scientific research. The principles of a healthy diet are described in Box 1.

Fruits and vegetables

Although there are many campaigns to encourage the public to consume more fruits and vegetables (due to the protection they offer against chronic diseases such as CHD and some cancers) many do not consume the recommended five portions each day (BDA, 2001).

Fresh, frozen, tinned, dried or juiced fruits and vegetables should all be encouraged. Potatoes do not count because they are a starch. A portion - 80g - includes:

- One apple, banana, orange or other similar-sized fruit;

- Two plums or similar-sized fruit;

- Three heaped tablespoons of vegetables;

- Three heaped tablespoons of beans or pulses;

- A 150ml glass of fruit juice.

Starchy complex carbohydrates

Starchy foods such as rice, pasta, bread, cereals and potatoes should form the basis of each meal. They are a good source of energy and provide a range of nutrients. Where wholegrain varieties are chosen they also contribute significantly to fibre intake. People should be encouraged to eat insoluble fibre (the body cannot digest it and it passes through the gut helping other food and waste products move along) and soluble fibre (it can be digested by the body and may help to reduce cholesterol).

It is a myth that starchy foods are fattening - they contain less than half the calories of fat: 1g of fat has 9kcals, whereas 1g of carbohydrate has 4kcals. It is the fat added to starchy food that increases the calorie content.

Low-carbohydrate diets have had a lot of publicity, particularly in relation to weight loss. Such diets can be high in fat, limit the amount of fruit, vegetables and fibre in the diet and can cause problems with constipation, osteoporosis and halitosis (BDA, 2003). A study published in the New England Journal of Medicine (Samaha, 2003) concluded that further studies on low-carbohydrate diets are needed before they can be endorsed.

Cutting out any food group from the diet whether for weight loss or unproven food intolerance can lead to serious health implications (and may result in nutrient deficiency) and should not be undertaken without adequate medical and dietetic supervision.


Excess fat in the diet can lead to weight gain and cardiovascular problems. As a guide women should have no more than 70g/day of fat and men more that 95g/day. There are three types of fat:

- Saturated;

- Polyunsaturated;

- Monounsaturated.

The ‘bad’ fats are the saturated fats, for example hard fats, butter, fat on meat and trans-fats or hydrogenated fats, which are processed to make them hard, found in processed foods like cakes and pastries. These ‘bad’ fats can raise cholesterol and increase risk of heart disease and therefore should be reduced in the diet.

The ‘good’ fats are unsaturated and are polyunsaturated - for example sunflower, soya, sesame, corn - and monounsaturated - for example olive and rapeseed. Omega-3 fats are classed as essential fatty acids as they cannot be made in the body. They are found in oily fish.

However, extremely low-fat diets limit the intake of essential fatty acids and fat-soluble vitamins. It is important not to overeat fats as they are all high in calories.


Dehydration can cause nausea, tiredness, constipation and headaches. In the typical UK climate drinking about eight glasses of fluid a day will be adequate, but requirements will be increased for anyone who is in a warm environment or who is undertaking any activity that causes them to sweat.

Caffeine, which is found in tea, coffee, cocoa and some carbonated drinks, can have a mild diuretic effect. People who drink lots of tea or coffee may need to alternate caffeinated drinks with a decaffeinated version, a naturally caffeine-free herbal infusion, water or squash.


A diet high in salt can lead to high blood pressure and increase the risk of stroke. Salt in the diet comes from the salt that is added during cooking and at the table, but up to 75 per cent of our intake can come from salt that has already been added to food before it is purchased. Some foods are not obviously high in salt but can contain ‘hidden’ salt so it is important to look at food labels. Although the recommended daily intake of salt is only 6g many people will eat close to 9.5g.


Alcohol in small quantities can actually have a beneficial effect on health, but drinking too much can cause problems. Alcohol is high in calories and so can contribute to excess weight gain. Heavy drinking over a long period of time can result in liver damage and increases the risk of high blood pressure, which is linked to coronary heart disease. Alcohol is also a diuretic.

The current guidelines are that women can drink up to 2-3 units of alcohol a day and men up to 3-4 units a day. Ideally these units should be spread throughout the week, with one or two alcohol-free days every week. Binge drinking should be avoided.

Nurses’ health promotion role

Registered dietitians and nurses can work together to advise people on healthy eating. All nurses play a vital role in the promotion of healthy eating. Primary care nurses, in particular practice and school nurses, are well placed to promote healthy eating.

The new Essence of Care benchmark for health promotion, due in March this year, is likely to include the need for nurses to ensure the information they give patients about issues such as healthy eating is as up to date as possible (Strachan-Bennett and Hainsworth, 2004).


This article has outlined what healthy eating is and why a healthy and balanced diet is important. However, healthy eating advice is aimed at adults who are well - children, older people, those who are ill or have specific dietary needs (such as pregnant women) will have different dietary requirements and the general healthy eating principles may not apply. Healthy eating is all about getting the balance right, with the right food and fluid.

Healthy eating should not be about short-term change but long-term measures that are put in place with the emphasis on enjoying more of the foods that protect and nourish the body. This is done by choosing a variety of foods from each of the different food groups each day and remembering that there are no healthy or unhealthy foods - just healthy or unhealthy diets. 

For many people this will mean big changes, but they should remember to make changes to their diet slowly. As prime minister Tony Blair said in his foreword for the public health white paper (DoH, 2004b): ‘Small changes in the choices people make can make a big difference.’

- This article has been double-blind peer-reviewed.

For related articles on this subject and links to relevant websites see

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