Getting over crack habit

I crack my knuckles and people always say, "Ooh, you'll get arthritis." Is that true? Cracking my knuckles is a habit, but my elbows, knees, ankles and toes all crack on their own with alarming regularity.

The noise comes from ligaments stretching, not from the joints at all. Cracking your joints does not cause arthritis and is not a sign of early arthritis. It is, however, a very annoying habit if performed repeatedly.

Infectious colours

My three-year-old daughter loves to get her face painted. Whenever we go to a school fete or any other place where face painting is available, she always clamours to have it done. I have tried to hold her back as I worry that the brushes may spread infection. What do you think?

It is hard to get a clear answer on this question. I spoke to a dermatologist who said that most face paints sold in this country and from the EU would not contain potentially dangerous chemicals. The main risk is from allergic reactions and you would want to exercise care with children with eczema and sensitive skin.

Using the same brush on several children is unlikely to spread any infection unless one of them has an open cold sore or impetigo (crusty, open sore). Most common childhood infections including colds and chickenpox are spread by droplets in the air, so your daughter is more likely to catch a bug from standing in the queue rather than from the face painting itself.

Sniffing out my loss

My sense of smell has completely diminished over the past few years. I have been to the doctor and he can't find a blockage, so it is not a sinus/nasal problem. I have not got around to going to a specialist yet. I am 27, a non-smoker and vegetarian (I eat fish, but not eggs), and I am careful about eating a balanced diet. I can't seem to find much information on the subject. The only thing I could come up with is maybe a zinc deficiency. Could this be the case?

Loss of smell, or anosmia, is potentially dangerous as you can't smell gas or something burning. It is usually temporary and caused by a cold or sinusitis. But if it persists, you need to see an ear, nose and throat specialist. The usual causes are nasal polyps, allergies or dental problems.

Rare causes are side effects of medicines, insecticide poisoning and radiation treatment for cancers of the head and neck or brain tumours. Deficiencies of copper, zinc or other trace metals have been touted as causes but are hard to prove. Often no cause is found and the sense returns as mysteriously as it once disappeared.

Diet for indigestion

I have always suffered from indigestion, and have found that cutting out foods containing yeast, such as bread and beer, seems to help. Is there a medical reason for this, or might the improvement be psychosomatic?

Some allergy specialists believe that there is a condition called gut fermentation syndrome. Sufferers convert sugar into alcohol in their gut due to fermentation because the good bacteria which aid digestion are overwhelmed by other less helpful organisms such as candida. This is said to contribute to irritable bowel syndrome, aching joints and tiredness as well as to a tendency to vaginal thrush.

Repeated courses of antibiotics make matters worse. A low yeast, low sugar diet may help. Yoghurt containing lactobacillus to restore gut bacteria and a course of anti-fungal drugs should restore your gut's status quo. Gastroenterologists tend to scoff, but if it works for you, I am sure you will become a believer.

Deciding to circumcise

I want to be circumcised. But I am having diffculty finding a doctor to do it. My GP feels the operation is unnecessary. How can I get the operation carried out?

It is unlikely that you will be able to get it done on the NHS or persuade a private health insurance company to fund it. Many urologists will agree to do the operation privately for you. Your GP should be willing to recommend one or you can phone a private hospital or clinic. Ring the urologist's secretary first to find out whether they do circumcisions and to get a price. While respecting your decision, I advise you to consider the pain and expense. If you go ahead, ask for a general anaesthetic and a week off work.

• These answers are intended to be as accurate and full as possible, but should never be used as a substitute for visiting a doctor and seeking medical help. If you have a question for Dr Robinson, email drann@dircon.co.uk or write to her c/o The Health Editor, The Guardian, 119 Farringdon Road, London EC1R 3ER. She regrets that she cannot enter into personal correspondence.