It may be St Valentine's Day this week. But 14 February is also National Impotence Day – highlighting "la différence" in the way men and women can't do it. For men, it seems, the problem is normally "hydraulic" whereas for women, it's mostly in their heads. And the good news is we can all do it better. Here's how both men and women can boost their sex drive.
Artichokes, like wine, are good for ladies when men consume them, according to an old French saying. No surprise that the country that invented champagne also had the idea that food can improve lovemaking: until recently, French bridegrooms were given asparagus on the eve of their weddings. There's no science to suggest it did any good – but is there an evidence base for other favourite aphrodisiacs?
* Pumpkin seeds, along with Brazil nuts and almonds, are rich in the amino acid arginine, boosting levels of blood to the genitals, making them natural Viagra, according to both the nutritionist Patrick Holford and the television pundit Gillian McKeith. in 2005, McKeith caused a stampede on UK supermarkets when she revealed the power of the pumpkin seed on the female libido – though there's no sign of either sex rushing back to buy new supplies.
* Oysters, the richest source of zinc, nourish the prostate gland and boost testosterone production, according to the nutrition consultant Suzannah Olivier (author of Food Medicine, Robinson).
* Chocolate contains phenethylamine, a nutrient that enhances mood and is the chemical we produce in our brains when we fall in love, according to Olivier. "The higher the cocoa content of the chocolate the better the effect, so stick to 60-70 per cent cocoa solid chocolate," she says.
* It's the smell of food rather than its constituent parts that gets men in the mood, says the neurologist Alan Hirsch, the founder of the Smell and Taste Treatment and Research Foundation in Chicago. He measured the effects of aromas on penile blood flow and found that American men responded best to doughnuts, pizza, popcorn and strawberries. Men, he concluded, are turned on by smells that evoke the security and pleasure of childhood. Vanilla apparently works for the same reason.
* Any dish can be erotic when enjoyed with sensual pleasure, according to Dr Michel Odent. We all need substantial bursts of the "love hormone" oxytocin to get sexually aroused – and that's less likely to happen if his body is fizzing with stress hormones or her rational brain is on overdrive. Physically enjoying food quickens production of this pulsating hormone, as do dim lights and softly playing music, says Odent. His book The Scientification of Love (Free Association) provides the evidence base for the St Valentine's Day dinner date.
* Being wined as well as dined boosts endorphins, the pleasure hormones helping to release tension and inhibitions as well as testosterone, encouraging flirtatious talk. Too much wine, however, reduces men's sex drive and women who drink too much are more likely to have sex but less likely to enjoy it, according to research.
It's exactly 10 years since Viagra exploded into the public consciousness. As the first oral treatment for erectile dysfunction (ED), it quickly became one of the biggest success stories in pharmaceutical history – outstripping the "sunshine" antidepressant pill Prozac as the fastest-selling medicinal drug ever.
A consequence of Viagra's success was that it overturned the widespread view that ED was mostly in the mind. While stress and other pressures can disrupt male sexuality, persistent dysfunction usually has a physical cause – most frequently the first signs that the blood vessels are clogging up (atherosclerosis). "The blood vessels to the penis are among the smallest in the body and ED is often an early symptom of atherosclerotic disease, which is also a risk factor for heart disease and stroke," explains Dr David Goldmeier, a consultant in genito-urinary medicine at St Mary's NHS Trust in London.
Anyone suffering from ED should get their health checked for diabetes, obesity, high blood pressure and abnormal cholesterol, all of which need to be addressed. In the meantime, medication such as Viagra can be used to improve penile blood flow and therefore erectile function.
One in seven men doesn't respond to Viagra, however, while others have unacceptable side effects. A firmer favourite is newcomer Cialis, known as the first morning-after pill for men: the effects last for at least 24 hours, which means men with ED can have sex at night and again the next morning. "Preference studies have been published showing that on the whole men prefer Cialis because they get a better erection," says Dr Goldmeier – "though the studies were funded by its manufacturers of Cialis and need to be treated with caution."
Testosterone is essential to libido in both sexes and supplements in the form of gels, sprays and patches are available for both sexes. However, testosterone patches and gels (Andropatch, Testoderm, Androderm) are only licensed for the one in five 60-plus men who suffers from hypogonadism (very low testosterone levels). And female testosterone patches and sprays that are on the market as "the female equivalent of Viagra", to treat the newly recognised problem of female sexual dysfunction, are highly controversial. The British Society for Sexual Medicine does not recommend testosterone for women unless they are shown to have unusually low levels: "Low female sex drive is a much more complex thing than men not getting an erection," it says, warning of excess facial hair as a common side effect – not necessarily the look you want on St Valentine's Day. As Dr Phil Hammond points out in his new book, Medicine Balls (Black & White Publishing): "If you look at the criteria – not feeling like sex for a few days in the last month – then I've got female sexual dysfunction too."
The impact of hormone replacement therapy (HRT) on female libido has been pretty well written out of the equation during the recent repeated health scares that have linked post-menopausal oestrogen to a small increase in the risk of breast cancer. Bear in mind, however, that HRT was first seen as a miracle anti-ageing drug that zapped post-menopausal low libido along with the hot flushes – with a series of older female celebrities expressing their gratitude to the hormone therapy for enabling them to remain a little bit tarty-looking well into middle age and beyond.
The fine print of maintaining surging oestrogen levels was always a bit vague. Perhaps the single most important effect is the role of oestrogen in lubricating the tissues of the vagina – with plenty of evidence that the devastating impact on couples' sex lives following the menopause is particularly due to vaginal symptoms such as dryness and discomfort. For those considering HRT purely as a sex aid, doctors are likely to recommend oestrogen cream or slow-release suppositories that have an impact on the genital area.
One step removed from these sex hormones is another popular anti-ageing hormone, DHEA (Dehydroepiandrosterone), a natural precursor of both testosterone and oestrogen that, according to enthusiasts, can be taken as an oral supplement. It's widely touted on the internet as boosting libido – though so far without a shred of evidence.
Medication is almost never the whole answer to sexual problems: half of men who begin Viagra or Cialis are no longer taking it after a year. It takes two to tango, says Dr Goldmeier, and there isn't a prescription drug to cure relationship problems – and good communication is also needed.
The first step is to confront the problem: "Men so often feel self-conscious about coming to me with their difficulty and don't realise it's my job to talk to men in the same situation," says the urologist Dr Mike Kirby.
But there can still be problems once everything is working properly. Couples counsellor Tricia Barnes says it's common for couples to continue to experience an emotional barrier which prevents them enjoying their love life to the full, once the male partner can obtain and maintain reliable erections again.
"The fear and anxiety about sexual functioning may have been alleviated, but fear of establishing or re-establishing emotional intimacy remains," she says. Marriage guidance or couples counselling can help people communicate more openly and honestly including being able to talk about their likes and dislikes in bed.
The brain is said to be the biggest sex organ – so if you feel good you're more likely to get sexually aroused, and vice versa. A sudden inability to get an erection is most likely to have a psychological background in a man: often caused by anxiety or loss of confidence as a result of divorce, bereavement, redundancy or a similar life event.
More generally, sex becomes less alluring through boredom, incompatibility, low self-esteem, depression and fatigue and, particularly for women, a combination of lifestyle and physical changes that occurs, for instance, with the arrival of children and their departure from the family nest. So sensible guidance encourages a multi-faceted approach to sexuality, including: exercise to improve stamina and body image; improving skills to cope better with work and financial stress; and, for women, pelvic floor exercises to create better awareness of the muscles involved in sexual pleasure, boosting libido and self-esteem at a stroke.