Every day scientists are discovering new benefits of fruit juices. Recently, US researchers revealed that beetroot juice can keep dementia at bay, as it contains nitrate, which opens blood vessels, boosting blood supply to the brain. Find out what ailments other juices help to treat. But too much is bad for the teeth — and waistline. Pomegranate juice How it works: Pomegranate juice fights prostate cancer. It contains chemicals which reduce cell damage and potentially kill cancer cells, according to scientists at the University of California. They asked 50 men with prostate cancer to have a glass (0.24 litre) of the juice daily. They then kept track of the men\'s levels of prostate-specific antigen (PSA), a protein linked to prostate cancer. Usually cancer patients\' levels double in 15 months but in patients who drank pomegranate juice it took an average of 54 months for their PSA levels to rise. What else: Fights heart disease and lowers \"bad\" LDL cholesterol — antioxidants in pomegranate juice reduce the formation of fatty deposits on artery walls. (Antioxidants are compounds which destroy free radicals, harmful molecules produced by the body and environment and are linked to many diseases, including cancer.) It is always best to have fresh juice where possible but if not, go for pasteurised over concentrates which can be packed with sugar. Purple grape juice How it works: It fights memory loss. A study by psychiatrists at the University of Cincinnati found that drinking the juice daily improved patients\' memory significantly compared with a placebo. Experts think the grapes provide brain-boosting antioxidants. What else: It lowers cholesterol and can be as effective as a daily aspirin in helping to prevent blood clots. The fruit also contains higher levels of disease-fighting antioxidant compounds than apple juice, according to the US Department of Agriculture. Cranberry juice How it works: A recent study showed that cranberry juice prevents the growth of E. Coli, the most common cause of urinary infections. Researchers who presented their findings to the American Chemical Society said drinking a glass of the juice prevented bacteria from developing into an infection in the urinary tract. But the juice will not treat cystitis if the infection has already occurred. What else: Raises the levels of \"good\" HDL cholesterol through high levels of polyphenols the antioxidants in the fruit; reduces the risk of gum disease and stomach ulcers. Cherry juice How it works: It fights cramps and gout. Recent studies at Northumbria University have shown that runners who drank the juice of Montmorency cherries — a tart-tasting fruit that is rich in antioxidants — twice a day for five days before the London Marathon recovered much more quickly and experienced less muscle pain than those who didn\'t. It can also ease the agony of gout by helping the body to excrete the uric acid linked to the painful joint condition. What else: Drinking a glass of cherry juice a day offers the same health benefits as eating 23 portions of fruit and vegetables, according to a study. Pineapple juice How it works: It combats arthritis. The enzyme bromelain, found in the flesh and juice of pineapples, helps the body digest proteins but also has other benefits. When taken on an empty stomach, bromelain acts as an anti-inflammatory agent which has been shown to reduce arthritis joint pain and swelling. One study showed a combination of enzymes including bromelain may be a safe alternative to anti-inflammatory medicines for people with osteoarthritis of the knee. What else: Helps ease symptoms of coughs and colds and thins the blood, although doctors are not yet clear why. Orange juice How it works: Orange juice contains an antioxidant called hesperidin, which improves blood vessel function and reduces the risk of heart disease. US researchers found that men who drank 500ml of orange juice (containing 292mg of hesperidin) daily had lower blood pressure than those who took an antioxidant supplement. What else: Prevents the formation of kidney stones. Tomato juice How it works: Researchers have shown that lycopene, the substance that makes tomatoes red, is a great antioxidant. It protects skin from sun damage by neutralising the harmful effects of UV light. In tests, people who ate more tomatoes had 33 per cent more protection from sunburn. What else: Studies have shown that a regular consumption of tomatoes reduces the risk of prostate cancer. According to the Cancer Research UK, \"The evidence is promising enough to encourage men to eat more tomatoes.\"