Knowledge about nutrition can be looked at in many different ways, and the focus in any consideration of human diet depends largely upon the context and situation. Certain foods or nutrients may be deficient in the diets of particular groups of people, such as elderly widowers, teenage girls or even particular cultural groups. These deficiencies must be addressed when considering such groups. Other foods might be eaten excessively in some situations, and may need to be reduced significantly in the diet. All food types should normally be eaten by all people to ensure a balanced diet, though adjustments can be made to compensate for the lack of certain foods that make up a typical western diet, such as meat or dairy products. In some cultures, for instance, milk products are rarely eaten, if at all, and calcium is derived from other calcium-rich foods. Vegetarians and vegans can also obtain essential nutrients such as complete proteins from vegetables, pulses and grains rather than from meat. Overall, though, a varied diet is much more beneficial than a diet heavy in one or more kinds of food. And, as the saying goes, moderation is the best approach.
The food and drink that we consume each day have a direct bearing on our state of health. It is important to vary our intake of foods so that we are deriving the full range of nutrients and other substances that the body needs. Too much of one or two food types, even healthy foods, is not recommended for long-term health. In addition to being more healthful, a varied diet is also a lot more interesting for the taste buds. A balanced and adequate diet is essential to our wellbeing. The extra time and thought needed to prepare good quality meals is easily rewarded with increased stamina and alertness, better resistance to illness, and clear and healthy skin, eyes and hair. However, to maximize the health benefits of what we eat, we need to understand some basic nutrition requirements and principles, which are discussed below.
IMPORTANT FACTORS IN NUTRITION
Quality of Ingredients
Fresh food is superior to processed and packaged food because in the processing, some nutrients are lost, and often, less desirable ingredients such as sugars, fats, and chemical additives are added. Fruit, vegetables, bread, meat and dairy products should ideally be consumed when fresh. Also pay attention to the quality of the food. Fruits and vegetables are freshest and most nutritious when in season and locally grown, as they can be picked later in the ripening stage, whereas produce that is transported large distances is usually picked well before it is ripe, as it travels better and lasts longer. Look for signs of quality: good colouring; aroma; firmness, crispness or softness, as appropriate; no signs of disease.
Price is not always an indicator of quality, but in general, you get what you pay for with foods, and cheaper produce carried by one shop might be inferior in nutritional value than slightly more expensive produce in a neighbouring shop. Good chefs choose their produce very carefully because they know that quality ingredients result in tastier, more nutritious, and appealing dishes. Good produce might cost more, but it will be higher in nutritional value. Some people spend more to buy organic produce. While there has been some research into the advantages of organic food over conventionally grown food, it is still not clear if there is a significant difference in overall nutritional value. However, the flavour of organic produce is usually reported to be better, and the possibility of chemical contamination is also greatly reduced.
Range of Ingredients
No one food or food group can supply us with everything that we need for good health. An important principle of nutrition is to eat a wide variety of foods daily. This gives our body the best chance of obtaining all the nutrients required. A diet dominated by bread will provide plenty of starch and other carbohydrates, but will be deficient in some vitamins, minerals and protein. A diet heavy in meat will supply lots of protein, but again will be deficient in some nutrients and can also over tax parts of the system. On the other hand, eating mainly vegetables and fruit may provide adequate levels of vitamins, but energy from carbohydrates and strength from proteins may be insufficient.
When we consider specific vitamins, minerals and other elements of the diet, we can see more clearly that we need a range of foods in our diet to obtain all the nutrients we need for optimum health. For example, dietary zinc can be easily obtained from red meats and some shellfish, but vegetables are a poor source of zinc. For cobalt and molybdenum, it is the other way around: leafy greens have a high concentration, while meats do not. Vitamin and mineral supplements are not a substitute for a balanced, varied diet. Vitamins and minerals are not absorbed beyond the body’s needs, and the body will either eliminate what it does not use or store it, which can result in toxicity. Also, it is difficult to keep track of every vitamin, mineral, or nutrient that you need and eat. The simplest way to get what you need is to eat lots of different foods. It is also more appealing from a culinary point of view.
Cooking Methods Used
Cooking food is useful because it softens hard ingredients, increases the availability of some nutrients (eg. carotene), releases and mixes flavours, and makes foods (some of which are inedible when raw) palatable. While proper cooking may slightly reduce the nutritional value of food, over-cooking should definitely be avoided. In general, the longer the cooking time, the greater the nutrient loss. Boiling can leach (cause loss of) out large amount of nutrients, although in the case of soups and stews this is not a problem because the liquid is consumed. Cook rice, lentils, etc. by the absorption method, rather than by boiling in water and then draining off the nutrient-rich excess water. Frying, grilling, baking and barbecuing can convert some materials into carcinogens (cancer-causing substances) if the ingredients are burnt, although the quantities present are usually minute. With over cooking, the chemicals in foods can sometimes change from useful to detrimental chemicals. It is important to include raw foods in the diet, such as fruits, vegetables and nuts. A platter of vegetable sticks and a couple of dips is a simple and healthy snack or meal.
Excessive use of fats and oils can occur in frying and baking. Instead, try dry frying, grilling or simply using a smaller amount of fat or oil. To improve taste, use herbs and spices in preference to salt.
The cooking equipment can also affect food. Glass, stainless steel or enamel pots and pans should be used. Copper can interfere with the vitamins in food. The use of aluminium pots and pans is said to increase the amount of aluminium entering the body, which could lead to health problems such as muscle weakness, bone problems and Alzheimer's disease. Cooking with acidic foods in aluminium (eg. vinegar, tomatoes, citrus fruits) can make the situation worse.
After food is prepared, its nutritional value for the body can be affected by the way the food is eaten, and the circumstances in which the meal occurs. Chewing is the first stage in the digestion of food. Without going overboard, food should be chewed adequately to reduce the particle size, add moisture for easier swallowing, and to add a number of enzymes that will breakdown starches into sugars. Saliva, secreted from six glands within the mouth, contains the water and enzymes necessary for this stage of digestion. Once the food has been mashed and mixed with saliva, swallowing occurs. This involves the combined action of muscles in the mouth, tongue and throat pushing the bolus of food down into the pharynx. As the food goes down, the epiglottis stops it from entering the wind-pipe (larynx). It then passes through the oesophagus and into the stomach.
A relaxed state of mind and body is necessary for complete digestion. When you eat 'on the run', your mental energy is not on the meal but on other things, and your physical energy is being used to keep your body and mind running, and diverted from the important processes of digestion. Stress and tension can lead to poor digestion through poor chewing, unbalanced stomach acid release and bowel blockages.