What's your REAL age?

Look closely at these two celebrities - which one do you think is older? At 43, television presenter, Anthea Turner is four years older than Joan Collins's daughter, writer, Tara Newley, who is 39.

But forget birth dates - their biological ages tell a vastly different story. According to Dr Daniel Sister, Harley Street anti-ageing expert and director of the Radical Beauty Clinic, Anthea has a biological age 14 years younger than her 43 years, while Tara is just three years younger than her actual age.

Biological age, say experts, describes the age of our organs, skin, hair and immunity. It also assesses our emotional ability to cope with "age accelerators".

This means that depending on lifestyle, address, diet, stress levels and even pets, a 35-year-old person could have a body more than 10 years younger or older than their actual age.

In many respects, ageing is a result of "degenerative" factors overcoming "protective" factors. "Degenerative factors such as toxins, poor nutrition and ultraviolet light can strain the body," explains Dr Sister. "Vitamins, relaxation, emotional support and good nutrition nurture the body and help it to recover from challenges. You age more quickly when stress and degeneration outweigh the body's ability to recover."

Stress at work or in relationships, he says, can also be extremely damaging. "Stress leads to abnormally high adrenaline levels, poor sleep and, eventually, adrenal exhaustion where the body can no longer relax or cope well. Blood and nutrient supply become compromised, tissue becomes toxic and ends up ageing abnormally fast."

Dr Sister believes hundreds of factors, which slow or accelerate ageing, come into play every day of your life. He has constructed a questionnaire to analyse life expectancy. The answers are individually rated between minus 15 to plus 15, each figure representing a year. The factors below are just a sample of the full test.

"Leading a healthy lifestyle can set the clock back by as much as 20 years over the course of a lifetime," says Dr Sister.

TARA NEWLEY

Actual age: 39

Biological age: 36

MAJOR ANTI-AGEING FACTORS

Lives in London: -4
Beginning of a serious relationship -3
Smokes up to a pack of cigarettes a day: -7
Exposed to lots of sun in childhood: -5
No aerobic activity: -10
Yoga once a week: +3
Has no pets: 0
Optimistic life outlook:+10
Steady weight:+5
Eats two or three servings of leafy greens daily: + 3
Eats two or three servings of fresh fruit daily: +2
Prefers fish and poultry to red meat: +2
Gets enough dietary fibre:+2
Doesn't snack or eat late at night: +2
Takes a vitamin/mineral supplement:+10
Taking selenium supplements:+ 10
Intestinal dysfunction: -10
Low alcohol intake:+6
Walks instead of driving:+2
Mother of two children under five: -2

ANTHEA TURNER

Actual age: 43

Biological age: 29

MAJOR ANTI-AGEING FACTORS:

Lives in peaceful, rural area: +2
Is happily married: +10
Has never smoked: +7
Sunscreen and avoids sun: +2
Works out daily:+3
Lives with pets and animals:+2
Very optimistic life outlook:+12
Steady weight: +5
Eats two or three servings of leafy greens daily:+3
Eats two or three servings of fresh fruit daily: +2
Prefers fish and poultry to red meat: +2
Gets enough dietary fibre: +2
Doesn't snack or eat late at night: +2
Takes a vitamin/mineral supplement: +10
Taking selenium supplements: +10
Healthy gut: +10
Low alcohol intake: +6
Drives regularly: -2
Lives with three children aged between five and 10:-6

Each number represents "anti-ageing points". The more points you have, the younger your real age will be. The full questionnaire incorporates more than 50 different lifestyle aspects. For further information contact: the Radical Beauty Clinic on 020 7487 3220.