Don't turn your back on calcium continue…

You may even be at greater risk if you consider the other factors that contribute to osteoporosis:

• The decline in oestrogen. Up to half of women over the age of 45 have some degree of type 1 osteoporosis (bone loss is most profound during the first decade after menopause).
• Smoking. It suppresses the activity of the osteoblasts (the bone-building cells) and also causes changes in oestrogen metabolism in women, resulting in an earlier menopause.
• Being thin and/or fine-boned.
• Excessive use of alcohol. This reduces calcium absorption and damages liver and bone cells.
• Avery high intake of protein increases the amount of calcium lost by the body. Veganism. Avoiding all animal products means avoiding some of the richest sources of calcium.
• Lack of exercise. Physical inactivity or prolonged bed rest are associated with the loss of bone density. Astronauts experience noticeable bone loss when in space, due to the effects of weightlessness.
• Excessive, long-term use of salt, in addition to being bad for your health in general, leads to increased calcium loss from your bones.
• Pregnancy and lactation. If there is insufficient calcium in your diet while you are pregnant or breasffeeding, calcium will be drawn from your bones and teeth to provide for the growth of the baby.
• Little or no exposure to the sun. Housebound people, elderly folk and office workers often don't enjoy enough sunlight to assist their skins in the manufacture of vitamin D, which is needed for the absorption of calcium from the gastro-intestinal tract.
• Unbalanced diets. Not only quick-fix slimming diets are low in nutrients. Our average, modern-day diets often lead to an insufficient intake of nutrients. Although you might be taking in sufficient calcium-rich foods (like cheese!), you might be taking in too little of the other bone-fortifying nutrients such as vitamin D, magnesium (soy, dried beans, nuts), zinc (chicken heart and liver, beef liver, lamb), copper, manganese and boron, found in a large variety of other foods.
• Genetic inheritance accounts for 80% of the variance in peak bone mass. Blacks have a higher bone mass than whites and Asians, and men have a higher bone density than women. A strong family history is a risk factor for osteoporosis - daughters of women with osteoporosis have been shown to have lower-than-expected bone density.
• Certain health conditions such as diabetes, rheumatoid arthritis, Cushing's syndrome, amenorrhoea resulting from anorexia nervosa and/or excessive exercise, gastrectomy, immobilising diseases, male hypogonadism (low testosterone levels), chronic liver disease or malabsorption.
• Consumption of large amounts of black coffee over a long period of time.
• Hyperthyroidism and over-treatment with thyroxin.
• The prolonged use of drugs such as corticosteroids (cortisone).

What is the role of calcium in theJody?

Everyone knows that calcium is required for healthy bones and teeth, but most people believe that calcium is only important in childhood. Wrong! There is a need for calcium throughout one's life in order to build and maintain calcium levels in bone.

Calcium acts as a metabolic regulator. Changes in the level of calcium within the cell result in the switching on and off of the processes of muscle contraction and nerve excitation.

Calcium is also involved as a co-factor in many enzyme processes. It is needed in cell division, the immune system and is also required in order for blood to clot.

More recently there has been some evidence to suggest that calcium has a positive role to play in maintaining a healthy blood pressure.

Clearly, calcium is an essential nutrient and a major role player in our general wellbeing; good health being an essential prerequisite for shedding weight successfully and permanently.

Dietary sources of calcium

The major foods in the diet that contain calcium, include milk, cheese, yoghurt, white bread, white flour, and green vegetables. The absorption of calcium by the body is dependent on many factors, including the form of calcium in the food. The best sources of available calcium are dairy foods. Green vegetables and whole grain cereals contain phytates that bind calcium and prevent absorption.

A balanced diet is important for the provision of calcium and other bone fortifying nutrients throughout your life.

Making the most of meat

Meat only poses two possible threats, namely its visible fat and the fact that too much of any good thing is .... well, not much good. Eating too much meat means you are eating too much saturated fat, absorbing too many unwanted fat kilojoules and pushing your protein intake through the roof.

Enjoyed in moderation though, lean red meat (with all visible fat removed) is quite a bright star in the nutrient skies. It is rich in potassium, B vitamins, zinc and iron and an excellent source of protein. Served in small, lean portions with the addition of dietary fibre, red meat will enhance your health rather than harm it.

Fibre, as found in grains, dried beans and vegetables, helps to fight heart disease, digestive disorders and certain types of cancer. These foods, when served with meat, will assist your body in coping with the hidden fats in the meat. Fibre-rich foods will also help you feel satisfied faster and for longer - an excellent way in which to help you control your meat intake and so too, those unwanted fat kilojoules.

You can make some clever cuts in your meat consumption, and I am not referring to cutting it out. I mean buying and eating cuts that contain less of the hidden fats (often called the marble fat) and cholesterol-causing saturated fat. Be 'pound' wise and buy clever cuts. Those are the hind-quarter cuts such as fillet, rump, topside and leg of lamb. They contain the least hidden fats. However, even after the visible fat has been removed, you'd be surprised to know how much fat is hidden in what you deem 'pure' meat.

The cooking method also dictates how much fat you will eventually consume. Red meat actually loses weight during cooking or grilling on a rack, and depending on the period of time for which the meat is exposed to the heat, between 7 and 23% of the fat could drip away. That is provided of course you don't consume the pan drippings! With stews and casseroles, in which the fat becomes part of the sauce, no dripping away of fat takes place and it seeps into the cooking liquids. Those you end up eating by way of the gravy or a sauce. And needless to say, frying meat in fat or oil obviously adds even more fat (and unwanted) kilojoules to your unsuspecting body - rather a stupid thing to do if you want to be lean and healthy. So consider your cut and its cooking method with great care if you care about your weight.

Best of all course, is to go wild. it you enjoy red meat, 'have venison often. A very large serving of grilled game steak (300 g) will only add a humble 9,6 g of fat to your intake, whereas a similar serving of grilled beef steak (rump, fat removed) could add as much as 30 g of fat.

Similarly, if you enjoy poultry, be game for game. Ostrich, pheasant and quail are ultra-lean and 300 g of roast game will only provide you with about 10,5 g of fat. On the other hand, if you roasted (with the skin intact) and consumed its domesticated counterpart the chicken, the exact same size of serving will happily lay in the region of 39 g of fat on your body.

Be cautioned, though; game and venison tend to be dry - as a result of their low fat content - so don't defeat the whole object by adding buffer, oil, bacon, lard or cream to the dish. Use wine, fruit and stocks instead to moisten the meat. As for a sauce or gravy, the stock of game or venison is delightfully robust in flavour. Reduce your cooking liquid by boiling it rapidly with garlic, aromatic peppercorns and herbs until richly brown and thickened to your liking. A wiser, leaner and more nourishing bet than a creamy sauce, for sure.

Don't inhibit your^- nutrients

There is no point in trying to follow a healthy diet if you are not aware of the fact that the absorption of certain nutrients can be inhibited. In other words, their assimilation and uptake by the body can be hindered by some or other bad food combination with nutrient inhibitors.

The nutrients most at risk are calcium and iron. Thus, try not to consume calcium-rich foods with alcohol, high-fibre cereals or red meats - they restrict the absorption of calcium. This means for example, that it is not wise to combine cheese and wine or cereal and milk. Serve wine with low-fat meat, chicken, fish, fruit and vegetable snacks and your cereal with fruit juice instead of milk. Vitamin D, however, aids the absorption of calcium. As sunlight is an excellent way to improve your vitamin D levels, serve lean, fruity milkshakes around your pool instead of fruit juices. That way your body will benefit fully from your clever combinations.

The absorption of iron is hampered by the simultaneous intake of tea, red wine and high-fibre cereals, so don't serve, say, iron-rich liver with whole wheat bread or brown rice, Rather serve it with potatoes or white rice. On the other hand, foods rich in vitamin C assist in the absorption of non-heam iron (iron derived from vegetables), so combine those foods for optimum nutrition. For instance, a salad made from iron-rich spinach, vitamin C-rich tomatoes and sweet peppers would be an excellent choice for super-A nutrient absorption without any threat of inhibitors.

How drugs affect nutrients

The ways in which drugs alter nutritional balance tend to be subtler and take longer to develop than the effects of food on medication. Drugs may have an influence on food intake due to changes in taste and appetite, they may decrease the absorption of nutrients, change their metabolism or cause them to be excreted in increased amounts (accompanied by diarrhoea and vomiting).

Drugs that affect food intake

Sensitivity to taste is one of the more delicate senses which can be affected fairly easily. Some drugs dull the tastebuds and make eating a less pleasurable experience - which, of course, may have the effect of making you eat less. Three drugs which decrease the sense of taste are clofibrate (a cholesterol-lowering agent), levodopa (an anti-Parkinson agent) and penicillamine (a chelating agent).

One or more of the four basic tastes (sweet, sour, salty and bitter) may be affected. For example, amphetamines decrease sensitivity to sweetness, while fluorouracil (a cytostatic agent) increases it. Diabetics who have to use insulin over prolonged periods find that they experience decreased sensitivity to both salty and sweet tastes. Other drugs - such as allopurinol (an anti-gout agent) - simply leave an unpleasant taste in the mouth.

Drugs that alter appetite

As the table below shows, some drugs directly stimulate the appetite, while others depress it. (Oral contraceptives, for example, tend to have the former effect.)

Drugs that decrease the absorption of nutrients

Drugs can affect the absorption of nutrients in several ways (including changes in the time the food spends in the digestive tract, in the acidity of the stomach, bile acid activity, enzyme systems, mucosal cells, or through binding to nutrients).

Firstly, the absorption of certain nutrients may be affected when the digestion of food is accelerated - a side effect of certain pills given for high blood pressure (ganglion blockers) - or when micro-organisms necessary for digestion are destroyed. In particular, drugs used to prevent indirectly the absorption of cholesterol from food into the body are often accompanied by reduced absorption of other nutrients (especially fat soluble vitamins). As another example, antacids are given to 'mop up' the excess acid in the stomach, but thiamin (vitamin B1) needs an acid medium lower down in the digestive tract to be absorbed, so antacids may impair its absorption.

Drugs that affect nutrient metabolism

Interference with nutrient metabolism can occur when a drug is similar in structure to a vitamin and therefore displaces a vitamin in a metabolic pathway. One example of this is the interaction between methotrexate (amethopterin), a cancer chemotherapeutic agent, and folic acid. Methotrexate kills cancer cells by displacing folic acid

and is therefore called a 'folic acid antagonist'. The problem is that the healthy cells are also prevented from using folic acid, which results in a type of anaemia.

The Pill and vitamin deficiency

The effect of oral contraceptives on nutritional deficiences has received wide attention in recent years. It has been shown that usage of 'the Pill' can decrease the absorption of vitamin B12, vitamin C, folic acid, vitamin B6, riboflavin, magnesium and zinc. On the plus side,however, it increases iron and calcium absorption. Although the Pill does seem to affect absorption and metabolism of many nutrients, there is little scientific evidence that women using it require increased amounts of nutrients to prevent nutritional deficiencies, provided of course that they are healthy and are following a balanced diet. In these circumstances, nutrient levels do not fall to alarming levels.

Some researchers have however established that the depression suffered by certain women who use the contraceptive pill can be due to a deficiency in vitamin B6, which can be treated by supplementation with this vitamin. A number of theories have been proposed regarding the cause of the pre-menstrual syndrome (PMS) and its link to the Pillone of these being that women who suffer from PMS also have low levels of vitamin B6. However, there is as yet not enough scientific evidence to justify fortification of the Pill with vitamin B6, or to suggest that doctors should treat the problem routinely with vitamin B6 supplementation.

How food affects drugs

In order to work properly, drugs must be present in the correct amounts at the receptor sites of the cell membranes. A number of factors can affect the way in which a drug works and, therefore, its effect on the body. Food is one of the most important of these factors. It can affect the absorption of a drug, its movement through the blood, its metabolism and its excretion.

Food and drug absorption

When drugs are taken orally, their absorption is influenced in different ways by the presence of food in the digestive tract. For example, food causes increased secretion of hydrochloric acid (HCl) in the stomach which can result in the destruction of some penicillin antibiotics that are taken by mouth. For this reason, penicillin should always be taken 1 hour before or 3 hours after meals.

Calcium in milk and dairy products tends to bind with tetracycline antibiotics to form non-absorbable compounds, with the result that the drug is lost in the stool. This means that these foods should not be eaten at the same time or within a few hours of taking the medication. However, the instruction 'Not to be taken with milk products' which sometimes appears on medicine labels can be misleading as it does not mean that you cannot consume any milk products while you are on the medication.

Iron salts (such as ferrous sulphate) can also bind with tetracycline antibiotics and result in the loss of the antibiotic. Therefore, anyone using an iron supplement as well as a tetracycline should take them at least two hours apart.

On the other hand, the absorption of some drugs can be increased when they are taken with foods. For example, foods with a high fat content increase the absorption of Griseofulvin, an antibiotic and antifungal drug. Iron supplements are also absorbed better when they are taken with vitamin C or foods rich in vitamin C, such as orange and guava juice. Interestingly, although some drugs (such as aspirin) are absorbed better on an empty stomach, they should nevertheless be taken with food - or at least milk - because of their irritating effect on the stomach lining.

Food and drug metabolism

Certain reactions inside the body can chemically change a drug (`metabolize' it) so that it is quite a different compound by the time it leaves the bloodstream. For example, some drugs combine with body proteins as they move through the bloodstream, which has the effect of preventing these drugs from entering the cells where they were intended to act. Others are broken down into smaller chemical components by the liver, the kidneys and the digestive tract. The metabolism of specific drugs can be influenced by the following in food: protein content, alcohol content, charcoal broiling, certain types of vegetables, caffeine intake, dietary fibre and the times food is eaten in relation to drug intake.

Food and the excretion of drugs

When metabolized by the body, some food alters the pH of the urine making it either more or less acidic - which in turn affects the excretion of drugs and therefore, the duration of their effects. For example, if excretion is decreased, more of the drug will be reabsorbed into the blood and its effects will be prolonged.

As an illustration, vitamin C makes the urine more acidic, thereby reducing the excretion of acidic drugs like phenobarbital and aspirin. When taking an antibiotic for a urinary tract infection, it is beneficial to acidify the urine, because this will result in decreased excretion of the antibiotic.

What drugs should you take when?

In order to minimize the adverse effects of foods on drug absorption, metabolism and excretion, the timing of drug administration in relation to food intake is very important. This is why it is essential to adhere to any such instructions which may accompany a prescribed drug. For example:

• If rapid absorption of the drug is desired, the doctor/pharmacist may specify on the prescription that the drug should be taken before meals.
• Drugs that irritate the stomach (such as indomethacin, phenobarbitone) should be taken when the stomach is 'cushioned' with food. In this case, the prescription should specify that the drug is to be taken after (or in the middle of) a meal.
• Fat-soluble drugs should not be taken with a fatty meal, since the medication will be absorbed with the fat content in the food; because fat is digested slowly, the drug may not be absorbed into the bloodstream as rapidly as it should be.
• Acetylsalicylic acid, Bisacodyl, Erythromycin and tetracyclines should not be taken with milk (see above).
• Ampicillin, Cloxacillin and Erythromycin-based drugs, as well as stearate and Penicillin G should not be taken with fruit juices or carbonated beverages.