What is the difference between black and green olives, and is one better than the other?

Green olives are picked before they have been ripened by the sun and so contain the bitter-tasting chemical oleuropein. Black olives, however, are picked when ripe. An average 3g green olive contains around 3 calories and 0.3g of fat, while black olives have about 7 calories and 1g of fat. Olives bottled in olive oil can have another 25 calories each. The good news is that over half the fat in olives is the heart-friendly monounsaturated type.

Not surprisingly, those processed with brine can be incredibly salty. If you eat 20 olives you could notch up a little over 3g, more than half your daily salt maximum. Olives also contain small amounts of vitamin E, which is needed for our skin, and a range of supernutrients with antioxidant and antibacterial properties.

What can I eat to keep my prostate in good shape?

When it comes to helping to prevent prostate cancer, tomatoes are what you think of first. They are rich in the pigment lycopene, an antioxidant that collects in the prostate gland. Studies suggest that those eating ten or more servings of tomatoes a week, or tomato juice and purée, had a reduced risk of prostate cancer. Lycopene is best absorbed by the body from cooked or canned tomatoes, because the cooking loosens it from cell walls and fibre which otherwise make it hard to digest. Other foods containing lycopene include pink grapefruit, watermelon and papaya.

Meanwhile, a vitamin D deficiency has been diagnosed in many prostate cancer patients. Oily fish, such as mackerel, herrings and sardines contain vitamin D, as well as eggs. Another way to stock up on vitamin D is to get some safe exposure to sun each day between April to October. If you are not getting enough sun and vitamin D-rich foods, a 10 microgram daily supplement is a good idea.

Finally, some advice for younger men: keep your waistline in shape. A study reveals that white men who gained more than 10lb, and black men who gained more than 1st 11lb, from the age of 21 were twice as likely to develop advanced prostate cancer as their peers who stayed slim.

I drink six diet colas a day. Will the artificial sweeteners damage my health?

In terms of whether you will exceed the acceptable daily intake (ADI) of artificial sweeteners, the answer is no. In the case of the sweetener aspartame, which is used to sweeten diet drinks in the UK (often in conjunction with acesulfame k), you would have to drink 6-7 litres a day to reach the ADI. Your current consumption of just over two litres falls well short of this.

That said, I would advise you to cut back, if only because research indicated that women who drank four servings of cola a week over a five-year period had lower bone density, especially in the hip, which increases the risk of osteoporosis in later life. Cola also contains caffeine, and we are advised to consume no more than four caffeine drinks a day.

To read more of Amanda’s advice, visit The Times Health Club at timesonline.co.uk/healthclub You will find a further Q&A with her, and a fitness Q&A session with Matt Roberts. If you have a nutrition question, e-mail

amanda.ursell@thetimes.co.uk

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