Does a baby decrease cancer risk? And what exercise should I do?

CANCER CONFUSION

CANCER CONFUSION

I am constantly reading that the risk of breast cancer increases if you have your first child late in life, and I'm confused. Is the risk even greater if you never have children (I'm childless and likely to remain so)? Or is it having a child late in life that is the risk factor, rather than the length of time one has been childless?

For most women who develop breast cancer, there is no obvious cause. A very small number of women carry a gene that makes it more likely that they will develop the disease. When the characteristics of women who get breast cancer are compared with those of women who do not get breast cancer, several things stand out. One of these is the age at which the women have their first child. Women who have their first child early in life are less likely to get breast cancer than women who have their first child after the age of 30-35. Women who never have children have a similar risk to women who have their children late. So, it seems that having children at a young age provides some protection from breast cancer. Not having children at all, or having them after the age of 30-35, removes this protection. One theory is that breast-cancer risk is somehow linked to how long a woman is exposed to the hormone oestrogen in her lifetime. Nine out of 10 women will never develop breast cancer.

SLIMMING CHANCE

I am trying to both lose weight and get fit, but I can't decide what sort of exercise to do. Are some types of exercise better than others for weight loss? And is it possible to predict how much weight one can lose with certain types of exercise?

All types of exercise will help you to lose weight, but the more strenuous the exercise, the more weight you will lose. One pound in weight is equal to about 3,500 calories. So, if you eat 3,500 more calories than your body needs, you will put on about a pound in weight. If you burn up an extra 3,500 calories through exercise, you will lose about a pound in weight. The best combination is to reduce the number of calories that you take in, and also burn up some of your excess calories by exercising more. If you walk for half an hour at a good pace - about four miles per hour - you will burn up about 150 calories. To get rid of a pound you will need to walk for about 12 hours - that's about an hour and a half every day for a week. Fast jogging at eight miles per hour burns up three times as many calories. To lose a pound, you will have to jog for about a half an hour a day for a week. Try to find a sensible combination of reduced food intake and increased exercise.

DON'T LOSE SLEEP

I fly across the Atlantic about four times a year for work. The return flight from Chicago to the UK is overnight, and I find it very difficult to sleep on the plane. Consequently, I am exhausted when I arrive home and it takes me several days to recover. On my last flight, a friend gave me a sleeping pill, and it made a huge difference. I am reluctant to ask my doctor for a prescription for sleeping pills, because I know that she is reluctant to prescribe them in any circumstances. Are there any risks of addiction from taking three or four sleeping pills a year?

Doctors are reluctant to prescribe sleeping pills to healthy people because they worry that three pills a year will gradually turn into three pills a month, and then three pills a week, and then a pill every night. Long-haul air travel is physically exhausting. If you are able to sleep as you cross time zones, you are much less likely to suffer from jet lag and exhaustion. Don't hesitate to discuss sleeping tablets with your doctor. A prescription for five tablets will probably last you for more than a year. If you only take them when you fly, there is no significant risk of addiction. You may find that they become less effective as your body becomes accustomed to them. But the benefit that you derive from a good night's sleep will far outweigh any potential harm.

HAVE YOUR SAY: READERS WRITE

NK, who works for a major drug manufacturer, writes:

The person who was complaining of tablets appearing intact in the toilet bowl should know that some tablets are designed to pass through the intestine unchanged. The formulation is known as Gits (gastro-intestinal therapeutic system), which is designed to release the active medication from within the tablet as it journeys through the gut. The outer casing is not absorbed or broken down in this process, and appears in the stool apparently unchanged. In fact, the medication has been released and the patient will have gained benefit from it. Tablets that use this formulation normally offer an explanation in the patient information leaflet that comes with the tablets.

Questions, suggestions to A Question of Health, 'The Independent', Independent House, 191 Marsh Wall, London E14 9RS; fax 020-7005 2182; e-mail health@independent.co.uk. Dr Kavalier is unable to respond personally

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