Our early ancestors, having no hamburger bars and no tin-openers, probably lived on a diet consisting largely of fresh plant food: leaf and root vegetables, fruit, nuts and whatever was growing to hand. Meat and fish were luxuries, because hunting and fishing were time-consuming and possible only when there was a surplus of vegetable food in store. Millions of years of evolution adapted our bodies to this kind of diet. So it would be reasonable to assume that today – after only the blink of an eye on the evolutionary timescale – a diet with plenty of fresh vegetables and fruit but little meat and fish would still suit us. This simple assumption is now backed up by evidence from research, both into our dietary needs and into the dietary causes of disease. Modern advice for a healthy diet is relatively straightforward. Eat more cereals, vegetables and fruit; eat less meat and animal produce; eat fresh and unprocessed food where possible. A diet such as this has less sugar, less fat and fewer chemical additives than the more usual Western fare. All these things have the potential to harm us. On the other hand, ‘stoneage’ eating gives us more fibre, more complex carbohydrates (that is the starches in grains, pulses and roots), more vitamins and more minerals than we get from a meat-based, processed and packaged diet. These ingredients are all good for us, and may protect against a wide range of disorders.
Foods to cut down on
First let us consider the ‘baddies’, the foods most of us need less of. Fat’s best-known crime is probably its role in causing heart disease and strokes, by blocking blood vessels. The culprit seems to be saturated fatty acids from animals: milk and cheese, fat and lard for frying and of course meat itself. Fat is also concealed in processed foods such as sausages, biscuits, chocolate and pies. Reducing the quantity of animal fat in your diet is an excellent way to reduce your risk of cardiovascular disease although it must be stressed that the most effective way to protect yourself from heart disease is not to smoke. Eating well for your heart and blood vessels also seems to protect against certain kinds of cancer, including cancer of the breast and bowel.
What about carbohydrates? Plain sugar is sometimes described as an ‘energy food’. What this label actually means is that there is nothing in sugar except energy. This also explains another term: ‘empty calories’. The body can burn many foods to get energy, and anyone with a tendency to plumpness is already getting too much. This is bad enough, but most sweet foods contain simple sugars such as glucose and so deliver energy into the body all in a rush – the sugars dissolve and are quickly absorbed into the bloodstream. This sets the body’s carefully balanced energy-budgeting system swinging madly. The excess calories are soon disposed of, and two hours after the chocolate bar or sticky bun you can be left feeling let down, depressed and irritable – and tempted to eat more sweets. The complex carbohydrates in starchy vegetable foods pasta, rice and beans for example – provide plenty of energy but are released much more slowly into the bloodstream. This is because the large starch mole-cules must be broken down during digestion before they can be absorbed. This regular, even supply of energy is much easier for the body to cope with. Also, over-indulgence in sugary foods is a possible cause of diabetes mellitus.
Another major nutrient, protein, is of course essential to the daily maintenance and renewal of our bodies. It is a myth, however, that red meat is the only or even the preferred source of protein. Fish, beans, nuts and liver are just as good, often cheaper, and tend to bring with them a much wider range of nourishing substances.
Food additives, the chemicals added to food to preserve, flavour or colour it, are usually synthetic com-pounds not found in nature. In the West all of these are tested for safety, so they are not immediately poisonous. However, they may not all be completely safe and from time to time manufacturers or governments appear to have seconds thoughts and withdraw one or more of them. For example, many scientists believe that nitrate compounds, used to preserve bacon and sausages, may play a role in causing cancer of the stomach. Evidence also shows that children who consume large quantities of sweets and soft drinks containing artificial colourings and flavourings are more prone to be ‘hyperactive’ – irritable, hard to control and unable to concentrate. This behaviour can often be prevented by excluding artifically dyed or flavoured foods from their diet.
Foods to eat more of
Fibre keeps our bowels regular by giving them something to get a grip on. This undoubtedly helps to keep the digestive tract healthy and protects it from prob-lems such as diverticular disease, a painful condition in which waste matter builds up in little pockets in the wall of the large bowel, instead of moving smoothly through it.
To many Westerners, bran springs to mind as an obvious source of fibre. Fortunately the ‘stoneage’ diet is full of fibre, because plants have cellulose fibre instead of bones as their supporting ‘skeleton’. All unprocessed vegetables contain fibre: beans, peas and whole cereal grains provide plenty. But ‘regularity’ is only the first of many benefits of fibre. Its advantages are rather similar to those benefits ascribed to a low-fat diet – avoidance of cancer, gall-bladder disease, heart disease and bowel disease. This is not so surprising, because a high-fibre diet is likely to be low in fat. But there are many reasons to believe fibre brings its own benefits, in addition to the ones you get from avoiding fat. High-fat foods alter the blood chemistry and particularly the chemistry of the liver, our own internal food processor. Fibre, on the other hand, changes the chemistry in the bowel. It cuts down the length of time for which food (and possible poisons) linger, and it encourages ‘friendly’ bacteria to grow. These bacteria have evolved with us. We feed them fibre and they ‘look after’ our bowels, keeping them healthy and also providing us with certain vitamins. Without fibre, less friendly bacteria take over and under these conditions bowel cancer and gallstones are thought to be more likely.
Vitamins derive their name from the same Latin word that gives us vital – which they are. The vitamins and minerals we know about play a role in almost everything the body does.
Vitamins and minerals act together, too, in ways nutritionists are only just beginning to understand. For example, iron (essential for healthy red blood cells) needs to be eaten with folic acid and vitamin C in order to do any good; and vitamin B6 can have bad effects if the intake of magnesium is low. Processing tends to take vitamins and minerals out of food. Sometimes they are put back artificially, but because nutritionists are still not completely sure what we need, these replacements are almost certain to be incomplete. The simplest, most elegant and most natural way to get them all is by eating foods in their freshest possible state, before anything has been lost.