General Health Through Diet

• Health and Diet
• Nutritional Components of the Diet
• Macro and Micronutrients
• Proteins
• Carbohydrates
• Fibre
• Fats
• Essential Fatty Acids
• Phytochemicals
• Amino acids
• Vitamins
• Minerals
• How much?
• Health Food Supplements
• Further information
  

Health and Diet (top)
To maintain health generally and avoid diet-related diseases, we need to organise our lives to ensure that we eat the right foods in the right amounts, at the right times as well as ensuring we take sufficient exercise to maintain fitness and general well being.

A balanced and varied diet (see Achieving a balanced and varied diet) is usually enough to provide us with sufficient nutrients to maintain general health and well being, and will contain enough essential nutrients ie vitamins, minerals, amino acids and essential fatty acids as well as carbohydrates and fats for energy.

There is also growing evidence from epidemiological data and other research that phytochemicals (plants compounds) play a specific and important role in maintaining health as well as the known 'essential nutrients' - people who eat a diet high in fruits and vegetables have a significantly lower risk of certain cancers and heart disease, which cannot currently be entirely attributed to the vitamin or mineral content of these foods.

Western Diets

The reality is that in the present Western culture of long working hours, convenience foods, and other day-to-day pressures of normal living, many of us do not manage to achieve the optimum balance of diet and exercise required to maintain health.

In the developed Western world many people eat insufficient amounts of fresh fruit, vegetables, and unprocessed nuts, seeds and whole grain cereals. As a consequence the typical Western diet often supplies less than adequate amounts of several essential nutrients.

Nutrition surveys have found large numbers of people in the west and UK specifically consume too little calcium, magnesium, iron, zinc, and possibly copper and manganese, to maintain health.

This is the primary driving force behind the current UK government's '5 a day campaign' to encourage us to increase our fruit and vegetable intakes, and reflects the growing awareness of the important role that diet plays in maintaining good health.

There is also growing evidence that the micronutrient content of foods is reducing - one study has shown that the micronutrient content of foods has reduced by nearly 40% over the last fifty years.  Becuase of this and other evidence of growing micronutrient deficiencies, the World Health Organisiation has revised and increased its advice on the amount of fruit and vegetables to be consumed daily, to 9 portions.

For those of us who are unable or unwilling to follow recommendations for a healthy, balanced and varied diet or simply wish to increase our intakes of certain nutrients, supplementation is a valuable option to ensure adequate dietary levels of vitamins and minerals.

Nutritional Components of the Diet(top)

Macro and Micronutrients(top)

If closely followed a healthy, balanced and varied diet will provide adequate essential nutrients, by consuming foods from the five food groups in appropriate amounts.

Each group is made up of one or more macronutrients, each of which serves a different function in our bodies. The digestive system will then break these macronutrients into a form small enough to be absorbed and used in the body.

The macronutrients refer to general categories of foods i.e.: protein, carbohydrates, amino acids and fats. All three macronutrients are vital to our health

Micronutrients are essential nutrients we need only in very small quantities: vitamins, minerals, and amino acids. Optimal health depends on maintaining a good balance between macro and micro nutrient types.

Proteins(top)
Protein builds and replaces tissues, carries nutrients and oxygen through the bloodstream and to cells, maintains fluid balance, and helps maintain the hormonal chemistry that keeps the different metabolic systems in the body in balance. Approximately one-fifth of your body weight is made up of protein.

There are two types of protein, complete and complementary proteins:

Complete protein contains all essential amino acids. Sources of complete protein are seafood, soy products, eggs, milk, meat, and fowl.

Complementary protein requires two food sources to provide all essential amino acids. For example, beans and rice.

Carbohydrates(top)
Carbohydrates are the chief and preferred energy source for the body. There are three kinds of carbohydrates:

Complex carbohydrates are found in whole grains, vegetables, fruits, and legumes. Complex carbohydrates contain high levels of vitamins and minerals, which prevent disease and are used in literally thousands of functions within our bodies. They are also excellent sources of fibre, which promotes healthy digestion, lowers blood cholesterol levels, and decreases risks of certain cancers. As an energy source, the body can only break complex carbohydrates down slowly, which means that they provide a controlled, steady supply of energy.

Simple carbohydrates are found in honey, fruits, and fruit juices. Fruit juice is a rich source of vitamins, but simple carbohydrates may cause your blood sugar level to rise and fall rapidly.

Refined carbohydrates are found in table sugar, high-fructose corn syrup, and other sweeteners. They contain few nutrients and may also cause blood sugar to rise and fall rapidly.

Fibre(top)
Dietary fibre is the general term for the indigestible part of fruits and vegetables, and can be either soluble or insoluble (able to dissolve in water). Fibre is not an energy source but aids digestion and protects the health of your colon, and increasingly, certain types of plant fibres are being found to have other beneficial roles in maintaining health. Increasing the amount of fibre in your diet has numerous health benefits.

Digestion - Fibre stimulates increased output of enzymes secreted by the stomach and pancreas, thus improving absorption of nutrients.

Satisfaction - Fibre slows the rate at which your stomach empties, increasing feelings of "fullness." This is part of the way in which your body helps you to control the amount you eat and avoid over eating, which in turn helps to lower blood sugar levels.

Health maintenance - Fibre decreases cholesterol and the risk of heart disease, stroke, and certain cancers. An intake of 25-35 grams a day is needed for disease prevention.

Dietary Fats (top)
Excessive fat in the diet contributes to health problems, but this does not mean fat should be avoided altogether as some of these are an essential part of the diet - however certain types of fat are more harmful, and whilst they are a good source of energy, excessive quantities should be avoided. Fats are not all the same!

Monounsaturated fats are found in high quantities in olive oil, avocados, peanuts, and other nuts. These are generally considered the healthiest kind of fats, and research shows that diets high in this form of fat are generally much better for you than diets high in saturated fats.

Polyunsaturated fats are found in high quantities in most vegetable oils. They will tend to lower your total cholesterol but may also lower the good HDL cholesterol as well.

However, polyunsaturated fats that contain omega-3 and omega-6 essential fatty acids (that our bodies cannot make) are needed in maintaining general health. Omega 6 fats are generally found in higher quantities in seeds, grains, nuts, and vegetables eg. perilla oil, safflower oil, sunflower oil, soybean oil, walnut oil, wheat germ oil, sesame seed oil, rice bran oil, evening primrose oil, borage oil, and black currant seed oil.

Omega-3 fatty acids are found in beans, greens, seeds, perilla oil, flaxseed oil and fish, (especially cold water fish, such as salmon, trout, mackerel and sardines). Diets high in these fatty acids are associated with decreased risk for heart disease and other health problems.

Saturated fats are found in meats, palm and coconut oils, butter, lard, cocoa butter, eggs, whole cheeses and whole milk, most ice creams, and many processed foods. Saturated fats are associated with a variety of health problems, especially increased risk of heart attacks, stroke, and other blood vessel diseases, and excessive saturated fat consumption is the major dietary contributor to high cholesterol.

Hydrogenated or partially hydrogenated fats are fats that have been artificially altered to make liquid oils into more solid form, such as margarine. The chemical process of transforming these fats radically alters their molecular structure, making them difficult for the body to metabolise - worse still, they raise LDL (the "bad" cholesterol) levels and lower HDL ("good cholesterol") which can adversely affect heart health.

Omega 3 & 6 Essential Fatty Acids (EFAs)(top)

What is an Essential Fatty Acid?

This is a fatty acid that the body needs for normal healthy function, but like vitamins and minerals, these substances cannot be made or manufactured in the human body. Therefore, a sufficient amount of EFAs must be consumed in a 'normal' diet to maintain good health.

What are Omega 3 and Omega 6 Essential Fatty Acids?

Both Omega 3 and Omega 6 are polyunsaturated acids (ones which have multiple double carbon bonds in them) and cannot be synthesised in the body from non lipid precursors (biochemical molecules that are not fats). This makes them essential fatty acids that must be consumed in the diet regularly to maintain good health.

As a food substance, Omega 3 and Omega 6 EFAs have been the most studied with over 4500 clinical trials investigating the benefits and roles of these essential fatty acids, most using fish oil as a nutritional source of Omega 3s. Both nutrients need to be consumed in the correct balance.

Omega 3 EFAs are involved in many different body processes. Much research has been carried out to determine the roles they play in a whole host of different body systems. The most evidence exists for their role in maintaining cardiovascular system health, joint health, immune and nervous system health.

Omega 6 EFAs are generally necessary for skin and hair growth, regulating metabolism, promoting transport of fatty acids from the liver to the tissues and maintaining reproductive performance. Researchers believe that they have an important role in reducing the risk of heart disease, cancer and stroke.

Phytochemicals (top)

As scientific understanding is growing of the links between diet and health, a range of phytochemicals (plant compounds) have been identified that whilst not considered 'essential nutrients' are being found to play important roles in daily nutrition. Examples of these phytochemicals are plant sterols such as beta-sitosterol, complex carbohydrates, isoflavones and bioflavinoid compounds.

These plant compounds are not usually incorporated into cellular tissues or physiological structures and are 'non-nutritive', but they may have a direct effect on the regulation of normal physiological mechanisms and are important factors in the diet to maintain health. Specific examples of these are the plant sterols which help to regulate cholesterol absorption from the diet, and bioflavinoids.

A considerable amount of research is ongoing across the world to help nutritionists and physicians understand the specific roles of phytochemicals in our diet, the optimum levels for inclusion in the daily diet, and their specific influences in the normal maintenance and regulation of health.

Amino Acids (top)
Amino acids are the building blocks of protein. Twenty amino acids are needed to build the various proteins used in the growth, repair, and maintenance of body tissues. Eleven of these amino acids can be made by the body itself, while the other nine (called essential amino acids) must come from the diet. The classification of an amino acid as essential or nonessential does not reflect its importance, because all 20 amino acids are necessary for health. Instead, this classification system simply reflects whether or not the body is capable of manufacturing a particular amino acid.

The essential amino acids are isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. Another amino acid, histidine, is considered semi-essential because the body does not always require dietary sources of it.

The nonessential amino acids are arginine, alanine, asparagine, aspartic acid, cysteine, glutamine, glutamic acid, glycine, proline, serine, and tyrosine. Other amino acids, such as carnitine, are used by the body in ways other than protein-building and are often used therapeutically.

Foods of animal origin, such as meat and poultry, fish, eggs, and dairy products, are the richest dietary sources of the essential amino acids. Plant sources of protein are often deficient in one or more essential amino acids, but these deficiencies can be overcome by consuming a wide variety of plant foods.

To maintain health it is important to consume a proper mix of amino acids over the course of the day, although it is not necessary to eat them all at the same meal.

What are Vitamins? (top)

Vitamins are complex organic substances that are needed in very small amounts for many of the processes carried out in the body. Usually only a few milligrams (mg) or micrograms (mg) are needed per day, but these amounts are essential for health. Most vitamins cannot be made by the body, so have to be provided by the diet, although vitamin D can be obtained by the action of sunlight on the skin, and small amounts of a B vitamin (niacin) can be made from the amino acid (tryptophan).

Vitamins have a variety of functions in the body: some are co-factors in enzyme activity, some are antioxidants (prevent oxygen from doing damage in the body) and one (vitamin D) is a pro-hormone. If insufficient amounts of vitamins are available to the body because of a poor diet or some medical condition (eg malabsorption), certain symptoms will appear and can develop into a deficiency disease. Vitamin deficiency diseases are rare in the UK, but still occur in some parts of the world.

Supplementation with certain vitamins is recommended by the Department of Health for children from 6 months to 5 years (vitamins A, D, C), for women pre-conception and during the first 12 weeks of pregnancy (folic acid), for women with heavy menstrual losses (iron), pregnant and lactating women (vitamin D) and anyone over 65 years of age (vitamin D).

What are Minerals? (top)
Minerals are inorganic substances required by the body for a variety of functions such as the formation of bones and teeth, essential constituents of body fluids and tissues, components of enzyme systems and nerve function.

How much of each mineral do we need?

The body requires different amounts of each mineral. Some minerals are needed in larger amounts than others, eg calcium, phosphorus, magnesium, sodium, potassium and chlorine. Others are required in smaller quantities and are called trace minerals, eg iron, zinc, iodine, fluoride, selenium and copper. Despite being required in smaller amounts, trace minerals are no less important than other minerals. A general guide is to be found in the table Recommended Daily Allowances, which gives the amounts required to avoid deficiencies.

Each person has different requirements too, according to their age, sex and state of health. Certain groups of people may have higher requirements for specific minerals, eg those suffering from certain medical conditions, those recovering from illness and some athletes. These people need to ensure they obtain adequate intakes by eating foods rich in the mineral concerned; sometimes supplements may be useful.

The amount of a mineral people actually absorb can vary, and will depend upon their own needs, and how much they already have of that nutrient in the body. Minerals are fairly stable in normal food processing conditions.

Dietary recommendations for the balance of nutritional components can be found in the section 'Achieving a Healthy, Balanced and Varied Diet'.

Health Supplements (top)

If you think that your diet is not meeting your nutritional requirements and for whatever reason you are unable or unwilling to change your dietary practice, food supplements rich in Essential Fatty Acids, plant phytosterols, essential amino acids as well as a multivitamin & mineral supplement may be of benefit. However, supplements with high doses of single vitamins and minerals can be dangerous for your health and should not be taken without the support of your doctor or a nutritionist/dietician with recognised qualifications.

Further Information (top)

For further detailed information on Diet and Health, we would recommend that you visit the British Nutrition Foundation website at www.nutrition.org.uk .