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Fruits and berries boost winter health

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Icy winds, rain and snow have plunged sunny South Africa into the depth of winter and with the Arctic temperatures have come the usual plagues of colds and flu, including swine flu,which has appeared again. There are reports of patients who go on to develop pneumoniaand in some cases these unpleasant respiratory illnesses can even prove fatal, particularly in very young and in older patients.

The elements are truly conspiring against us. But nature always provides compensations. Just when we need nutritional support to protect us against winter viruses and bacteria, many healthy fruits that are rich in vitamin C and other phytonutrients that boost immunity, become available.

Cornucopia

We are indeed blessed in South Africa that so many vitamin C-rich fruitcome into season in our winter. There are all the citrus fruits, such as oranges, lemons, grapefruit, naartjies, and clementines, plus gorgeous strawberries, and guavas, that can supply us with the extra vitamin C we require at this time of year to provide protection against infections. Nowadays, other berry varieties, including raspberries, gooseberries and blueberries, are more readily available and can be purchased in some supermarkets.

These fruits and berries are also rich phytonutrientslike anthocyanins, phenolic acids, flavonoids, tannins and sterols, that can protect us against acute infections and other ailments, such as heart disease, cancer, and possibly even Alzheimer’s.

Research studies

A number of studies have been investigating the effect of strawberries on heart disease and cancer. A Canadian study showed that patients with hyperlipidaemia (raised blood fat levels) who had already been using a variety of dietary treatments, including soy, dietary fibre, plant sterols and nuts, to reduce their blood lipid levels, were able to reduce their LDL-cholesterol (‘bad’ cholesterol) levels even further by adding 454 g of fresh strawberries a day to their diets. The researchers also found that the high antioxidant content of strawberries caused a significant reduction in cardiovascular damage caused by oxidation in these patients (Jenkins et al, 2008).

Another study conducted in Finland showed that older non-obese adults with at least one risk factor for coronary heart disease(i.e. high blood pressure, raised blood fat levels, raised blood glucose levels), who ate a mixture of different berries for 8 weeks had signficantly improved platelet function, HDL-cholesterol (‘good’ cholesterol) and lower blood pressure, compared to control subjects (Erlund et al, 2008).

In Scotland, researchers assessed the ability of blueberry, pomegranate, blackberry, blackcurrant, raspberry, lingonberry and strawberry extracts to prevent the growth of cervical and colon cancers in a laboratory study. Strawberries produced the best results with an 80% reduction in the activity of cervical cancercells (McDougall et al, 2008).

Although these studies are just starting to investigate the potential protective effect of berries and more extensive investigations are required, there is an indication that eating fresh berries, particularly strawberries, may help to reduce the risk of heart disease and certain types of cancer.

Anti-viral effects

A number of animal and laboratory studies using cell cultures have indicated that berries have anti-viral, antibiotic and anti-fungal effects. Mulberry was found to be active against the HIV-virus, blueberry against giardia (a parasite that infects the digestive tract), various berries, including cranberry act against Helicobacter pylori (the bacterium associated with treatment-resistant gastric ulcers), blueberry and cranberry can help combat Escherichia coli (the bacterium that is at present wreaking havoc in Europe) and strawberry has anti-fungal properties. Scientists are no yet sure how berries achieve these protective effects, but it is possible that their high tannin content may be anti-viral, anti-fungal and antibiotic (Arbor, 2009).

Alzheimer’s Disease

Researchers are aware of the fact that diets rich in fruit and vegetables (i.e. rich in antioxidants) improve cognitive health, including Alzheimer's Disease.  Animal and laboratory studies show that the flavonoids and polyphenols from berries accumulate in the brain and have a beneficial effect on the function of neurons (structures in the brain and nervous system that transmit nerve impulses) via anti-inflammatory and antioxidant pathways (Arbor, 2009).

Human studies in this field are still scarce, but one preliminary trial indicated that after 12 weeks of eating blueberries, older adults suffering from early memory loss, showed significant improvements in memory function. Eating fresh berries regularly may thus help to slow down cognitive deterioration.

The down-side of berry consumption

As is usually the case when we consider any food or drink, there are also negative aspects to eating large quantities of berries to boost our health and immunity. Commercially produced berries may be contaminated with high levels of pesticides. The USA’s Environmental Working Group 2011 Shopper's Guide to the Dirty Dozen and Clean 15 Fruits and Vegetables, listed strawberries as number three of the fruits most heavily contaminated by pesticides, while blueberries filled position number 10.

To circumvent this problem of pesticide contamination, it is safest to use organically grown berries and fruits whenever possible.

Beating the winter blues

Those of us who are currently not only struggling to keep warm in this inclement weather, but are also plagued by colds and flu, can turn to the abundant supply of fresh fruits and berries that are on sale in the South African winter. Combat respiratory tract infections with citrus fruits, guavas and berries. If possible eat a variety of these fruits and purchase organically grown varieties, to beat the winter blues.

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