Low zinc levels in men can lead to impotence, low sperm count and a loss of interest in sex. The right zinc levels (up to 100 milligrams daily) will increase male fertility and sex drive. But don't overdo it, she warns, as too much zinc can reduce immune function.

Reid also recommends food high in vitamin B3 for a healthy sex life ¨C red chilli peppers, liver, kidney, sesame seeds, pine nuts, and even coffee.

"Vitamin B3 causes the veins to dilate and help the blood flow, which is especially good for men."

Robyn Salisbury, clinical psychologist and director of Sex Therapy New Zealand, says we could be enjoying a happy and active sex life well into our 70s and 80s if we look after our bodies.

"The better you treat your body, the better it will treat you. When we are younger, we can get away with having a horrific diet and still having a good sex life.

"But when we are older, we need to look after our health and well being if we want good and frequent sex," she says.

"By the time people are in their 50s, if you are a smoker and have a poor diet, particularly a high-cholesterol and high-fat diet, as well too much alcohol, it is going to impact on your sexual function.

"If your veins and arteries are blocked because of a poor diet, blood flow will not be as effective, which means men will find it more difficult to get an erection and women will find it more difficult to become aroused.