Avocados are a wonderful fruit but they have been given a bad name amongst slimmers because of the fat content.

But this fat comes in the form of beneficial essential unsaturated fats, which are exceptionally easy to digest.

Avocados are high in potassium, the mineral that helps prevent water retention and are also a rich source of vitamin E as well as vitamin C, B6, folic acid, calcium, magnesium and manganese. Avocados also contain lutein which is an anti-oxidant especially beneficial to the eyes. They have also been found to help produce collagen, which gives the elasticity to skin and is essential for maintaining bone health.

Avocados have been shown to help lower cholesterol as they contain a substance called beta-sitosterol which helps to stop the absorption of cholesterol in the small intestines. Beta-sitosterol can also help with blood sugar swings and may help to prevent a number of cancers including breast cancer. Epicatechin, the same antioxidant as found in green tea, is also present in avocados.

Avocados also contain another substance called mannoheptulose which has a cancer protecting effect. Mannoheptulose inhibits an enzyme which prevents the uptake of glucose into cancer cells. Cancer cells use glucose as their primary fuel so, by blocking the uptake of glucose into cancer cells, it is essentially starving those cells.

According to a new study watercress contains ingredients that help prevent damage to the body’s cells and DNA. The research, published in the American Journal of Clinical Nutrition in February, involved 30 men and 30 women, half of whom were smokers. They ate 85g of watercress a day for eight weeks — the equivalent of a small bag of pre—prepared salad — in addition to their regular diet. Damage to DNA is considered by experts to be an important trigger in the development of cancer.

The results of blood tests on the participants showed a 22.9% reduction in DNA damage to white blood cells. The researchers, from the University of Ulster, also noted a 100% increase in levels of the molecule lutein and a 33% rise in beta—carotene, both of which have antioxidant properties. Antioxidants help cells defend themselves against damage.

The research suggested that increased concentrations of carotenoids could improve the antioxidant effects. Carotenoids are naturally occurring food pigments that contain vitamins. The researchers concluded that ‘the results support the theory that consumption of watercress can be linked to a reduced risk of cancer via decreased damage to DNA and possible modulation of antioxidant status by increasing carotenoid concentrations.’

The benefits of eating watercress were especially notable among smokers, according to the study. This could be because smokers had significantly lower antioxidant levels at the start of the study compared with non—smokers, owing to their habit, it said.

Professor Ian Rowland, who led the project, said he believed the findings were “highly significant”. He said previous studies showed links between higher intakes of cruciferous vegetables and a reduced risk of several cancers. But he added: “What makes this study unique is it involves people eating watercress in easily achievable amounts, to see what impact that might have on known bio—markers of cancer risk, such as DNA damage. “Most studies to date have relied on tests conducted in test tubes or in animals, with chemicals derived from cruciferous vegetables. “Blood cell DNA damage is an indicator of whole body cancer risk, and the results support the theory that consumption of watercress is linked to an overall reduced risk of cancer at various sites in the body.

“The nature of the study group also means that the results are applicable to the general population eating a normal diet.”

Last year, scientists also published research showing how extracts of cabbages could kill off breast cancer cells when combined with chemotherapy. The new research found levels of potentially harmful triglycerides were cut by an average of 10%. Cells were also more able to fight off the damaging effects of particles known as free radicals. Cells were exposed to hydrogen peroxide, which generates large numbers of free radicals, and damage levels were recorded as 9.4% lower than would be expected.

We know that fruits and vegetables all do affect DNA damage, hence the five—a—day strategy to prevent cancer and although the watercress study and the cabbage research is interesting, we don’t recommend that you convert to eating 85g of watercress and stacks of cabbage each day. That’s an awful lot of cress and cabbage! Much better to look holistically at your diet and ensure that there’s plenty of fruit and vegetables, fibre and as little fat as possible. Having said that, it’s great to know there are simple things that people can do — like eating more vegetables — which could help them avoid getting cancers in the future.

So says a study from the German Institute of Human Nutrition published in the medical journal Cancer Epidemiology and Biomarkers Prevention in January 2007.

The study looked at over 200,000 women and showed that you do not even need to go to the gym to get the effect – housework had a significant reduction in breast cancer risk, specifically in postmenopausal women.

Earlier research in December 2006 had also shown this effect and found the benefit was greatest for those women with oestrogen receptor positive breast cancers.