Deodorants: the low-down

Every year, we spend £400 million on deodorants. We each sweat a litre of fluid a day from 2.6 million sweat glands, so should we be reaching for antiperspirants or are natural alternatives as effective?

WHY DO WE SWEAT?

We perspire to regulate our body temperature, but changes in weather, exercise, diet and medical conditions can increase the amount we sweat.

Sweat is a mixture of water, sodium and chloride and does not smell until it comes in to contact with bacteria. Unfortunately, bacteria occurs in moist parts of the bodies, including underarms.

ANTIPERSPIRANTS VERSUS DEODORANTS Antiperspirants stop us sweating by using zirconium and aluminium to block the pores which release the sweat. The astringent ingredients also contract pores, limiting the amount of sweat produced.

Deodorants mask the smell of sweat but do not prevent sweating. They contain a fragrance or have anti-bacterial ingredients, such as triclosan, which minimise the odour-producing bacteria effectively and safely. Deodorants may limit the smell, but they will still leave you with the wetness.

If you don't like the idea of stopping your body from sweating, deodorants are the best answer.

Some people believe that sweating is a natural way to release toxins - however, most are released through urine and faeces and in very cold countries, where people don't sweat as much, there have not been any marked health problems.

Most antiperspirants also contain a fragranced deodorant, although you can get unscented versions.

DO THEY CAUSE CANCER? Research at Reading University has suggested a link between the increase in breast cancer over the past 25 years and the introduction of antiperspirants.

Some researchers think that by preventing sweating, you block the excretion of toxins which can build up in the lymph glands and bring about a cancerous change.

Zirconium and aluminium in antiperspirants have also been found to enter cells and mutate DNA, which could lead to cancerous growth and disrupted hormone levels.

Breast cancer tumours in men and women tend to occur in the upper- outer section of the left breast, which could be because right-handed people apply more deodorant into their left armpit.

However, Cancer Research UK says there is no cause for concern because breast cancer is caused by a variety of factors including family health, lifestyle and diet.

Perfumes in deodorants can include preservatives such as parabens, which some scientists think accumulate in the body and disrupt sex hormones, which in turn can increase the risk of breast cancer.

However, other researchers say parabens have been used in 50 per cent of cosmetic products for years without problems.

WHAT ARE THE NATURAL ALTERNATIVES? Natural products do not act as antiperspirants to block sweat but are made of natural antibacterial agents and perfumes which limit the bad odour.

They come in a range of forms - from crystals to sprays and roll-ons - and are available in chemists and health food stores.

They are good for sensitive skins and contain natural anti-bacterial ingredients and essential oils for scent. Deodorant crystals are long-lasting and contain ammonium alum, which is a natural salt that prevents bacteria production and is not absorbed by the body, so it does not block pores (eg Crystal Spring, £4.49 for 90g, available from Holland & Barrett, pharmacies and health food shops, www.crystalspringltd.co.uk).

Other natural ingredients include zinc ricinoleate, which is a compound that keeps odour on the skin's surface so it doesn't become airborne and smell (eg Greenpeople, £6.49 for 75ml, in unscented and rosemary), but they last for only six hours.

Other naturally deodorising ingredients to look out for are witch hazel, lichen extract, sage and tea tree. Weleda Sage Deodorant Spray, £4.65 for 100ml, includes oil of sage and tea tree.

Applying sodium bicarbonate or baking soda directly to your armpits absorbs sweat and kills off the odour-producing bacteria. Cornstarch and talc also absorb moisture but could encourage bacterial growth.

SPRAYS VERSUS ROLL-ONS Sticks and roll-ons can be considered more effective because they are applied directly to the skin while aerosols simply spray ingredients into the air.

But any deodorant or antiperspirant works in the same way regardless of how it is applied. Aerosols dry quickly and are refreshing, and roll- ons can be applied exactly where you need.

SENSITIVE VERSUS SPORTS Sports antiperspirants which are labelled 'Extra Dry' or 'Active' usually contain more active ingredients than standard types and are designed to combat situations where you may sweat more than usual, eg after a sports match or in very hot weather.

However, the extra ingredients may cause irritation, especially if used after exercise or a hot shower when pores are open and the skin is soft.

Sensitive deodorants have less active ingredients so should sting less but are not as effective.

WHAT ABOUT '24-HOUR' DEODORANTS? Deodorants offering 24-hour protection simply contain more aluminium chloride to increase the effect. But this ingredient can cause irritation, such as redness and itching.

Trust Underarm Deodorant (Boots and Selfridges, £7.95 for

12.5g) is aluminium-free. One application claims to eliminate perspiration odour for five to 17 days and is not affected by washing, swimming or climate. It works by inhibiting the bacteria that leads to odour.

WHAT'S GOOD FOR SEVERE SWEATING? One per cent of Britons suffer from hyperhidrosis, which causes sweating hands, feet and underarms even in low temperatures.

Driclor (£5.45 for 20ml) and Anhydrol Forte (£4.42 for 60ml) contain 20 per cent aluminium chloride, which causes the sweat glands to swell up and gradually reduces the amount of perspiration that can be produced.

It is applied at night and washed off in the morning. The usage can be reduced when the condition is under control.

Both brands can cause skin irritation and sensitivity, so should be used only in severe cases.

CHEAP VERSUS EXPENSIVE Deodorants range from 59p (Superdrug roll- on in cottonfresh, pink, sensitive and sport) to more than £20. There is no difference in effectiveness between cheap and expensive brands.

Any antiperspirant will stop you sweating and any deodorant will mask the smell.

Expensive brands may be more popular because of their distinctive scent - eg Chanel's Allure deodorant spray, £22.99 - or natural botanic ingredients which are soothing for the skin - eg Dr Haushka's Floral Deodorant with anthyllis and jojoba oil, which are said to be calming for sensitive skins, £7 for 50ml.