November 11, 2005

Most people would like to practice healthy eating, but identifying the priorities can be a challenge. With so much information available through family, friends, and the mass media, and so much of it seeming to contradict, no wonder the average consumer sometimes fails to recognize the most established dietary guidance, supported by extensive scientific research and leading health institutions. One example of this, is the ‘5-a-day message’. International and national health experts around the world are in total agreement about the benefits of eating 5 portions (approximately 400g per day) of fruit and vegetables daily. Here AFIC outlines some key scientific conclusions on the health benefits of 5-a-day…

The scientists and your mother agree!

"Eat your fruits and vegetables" is both a traditional and scientifically established dietary guideline.

Worldwide, the WHO estimates that low intake of fruits and vegetables is estimated to cause about 19% of gastrointestinal cancer, about 31% of heart disease and 11% of strokes. An expert report published by the World Cancer Research Fund (WCRF) in 1997 estimates that 30 - 40% of cancer cases throughout the world are preventable through modifications to typical diets. This represents between 3 and 4 million new cases of cancer each year. The WCRF report states that the evidence for the role of diet in protection against cancer is strongest and most consistent for diets high in vegetables and fruits. The panel of experts concluded that the consumption of 400 grams/day or more of a variety of vegetables and fruits - could, irrespective of other diet and lifestyle patterns, decrease overall cancer incidence by at least 20%.

The 2003 World Health Organization (WHO) / Food and Agriculture Organization (FAO) expert consultation report on diet, nutrition and prevention of chronic diseases reported that there is convincing evidence that fruits and vegetables decrease the risk for obesity and cardiovascular diseases and also probably decreases the risk of diabetes.

Although all fruits and vegetables are believed to contribute benefits, green leafy vegetables such as lettuce and spinach, cruciferous vegetables such as broccoli, cauliflower or cabbage, and citrus fruits such as oranges, lemons, and limes (and their juices) make especially important contributions. Note that tuber plants, such as potatoes and cassava, do not count towards the 400g/day fruit and vegetables target but regularly including some of these starchy foods in the diet is important for other health reasons.

Barriers to Meeting the 5-a-day Target

A glance at some of the statistics on the WHO surveillance data website indicate that most Asian countries consumption rates fall short of the recommended target: China’s population on average consume about 300g/day; Thailand’s average consumption rate is recorded as less than 200g/day and surveys in India record about 130g/day.

There are multiple reasons why so many are consuming less than optimal quantities of fruit and vegetables and there is extensive work underway to examine how to overcome some of these obstacles.

Cost and convenience are important factors for many. But misunderstanding of the real health benefits and risks is also a factor for some. There are some consumers whose concerns about pesticide residues overshadow their understanding of the very well established benefits of fruit and vegetable consumption, but, there is no firm evidence to support these fears: Indeed, the 1996 Harvard Report on Cancer Prevention (Volume I: Human Causes of Cancer) concluded that 65% of cancer deaths in the United States can be linked to tobacco use, diet, obesity, and a lack of exercise, and that just 1% could be attributed to food additives and contaminants such as pesticides and/or chemical residues.

Multiple studies attest unequivocally to the benefits of 5-a-day, and studies to examine the health risks associated with exposure to pesticide residues have to date not demonstrated a significant, quantifiable risk to health.

Achieving the 5-a-day Target

To maximize the benefits gained from fruit and vegetables, the first guiding principle is to aim for as wide a variety of produce as possible. Choosing all colours of fruit and vegetables is a good strategy. For example many of the orange/yellow fruits and vegetables such as pumpkin and mango are a good source of the carotenoids, white vegetables such as onions, garlic are a good source of sulphurous compounds and the green vegetables are an excellent source of many B vitamins. Furthermore, increased fruit and vegetable consumption can replace foods high in saturated fat, salt and total energy content and thus improve overall nutritional quality of the diet. Consumers should not allow misplaced fears about trace contaminants to become a barrier to achieving the 5-a-day target.

400g of fruits and vegetables per person per day (excluding potatoes and other starchy tubers) for the prevention of chronic diseases translates to approximately five or more servings of fruit and vegetables every day. One serving can be estimated as roughly the amount that fits into the palm of a cupped hand. Obviously, those of smaller body size will need to consume less than 400g/day, so the 5-a-day cupped handful works as a guideline for children, young people and their parents, as well as smaller adults.

Examples of fruit and vegetables portion sizes for an adult

Ø       1 teacup of raw salad greens

Ø       1 medium sized piece of fruit

Ø       Small tumbler (150 mls) of 100% fruit or vegetable juice

Ø       ½ teacup of cooked veggies

Ø       ½ teacup of cut-up fruit and veggies

Ø       ¼ teacup of dried fruit

The recommendations suggest that individuals should aim for three vegetable serves and two fruit serves. Also health experts advise that dried, canned and especially frozen foods can also count towards the 5-a-day target. As a general guide dried, canned, juiced products can provide 2 of the 5 daily portions, and the remaining 3 portions are best in the form of fresh or frozen and relatively unprocessed.

Some Myths and Facts on Pesticide Use in Asia

For most Asian consumers, the fruits and vegetables they buy are likely to have been grown with the help of pesticides to protect against insects, moulds, viruses and other pests that reduce yield and quality. Here are some facts to address common myths underlying consumer concerns about pesticide-treated produce:

Myth 1: Farmers spray crops with so many chemicals, it’s dangerous to eat them

Fact - Although there are occasional examples of misuse and overuse of pesticide chemicals, the majority of farmers use pesticides responsibly and according to strict safety guidelines which ensure any residues are low enough for health to be unaffected. Pesticides cost money, and farmers have a strong incentive to use sparingly to keep down their costs.

Myth 2: Pesticides cause cancer

Fact - It is important to note that, to date, the studies that have examined possible links between approved levels of pesticide residues in food and ill health have been unable to establish any definite link.  However, the scientific evidence on the link between development of chronic degenerative diseases such as heart diseases and cancer, to a limited consumption of fruits and vegetables is undisputed.

Myth 3: We don’t know what chemicals are being used

Fact - Before allowing any pesticide to be used on a food commodity, limits are set on how much of a particular pesticide may be used on a crop during its cultivation, and the safe amount of individual pesticide compound residues that may be present on food at point of sale.

Myth 4: We don’t know what pesticides in the diet are doing to our health

Fact - One of the most important tools in the safety evaluation of pesticide use on food crops is the calculation of what is an Acceptable Daily Intake (ADI). The ADI for any given pesticide is a measure of the quantity of a particular chemical in food that can be consumed daily over a lifetime without any known risk to health. It should be noted that ADIs have significant safety margins built into them, usually in the order of 100.

Myth 5: Pesticides are poisons so even very tiny amounts must be toxic to the body

Fact – Most pesticides are designed to breakdown soon after application so many crops treated with pesticide before harvest will have no residues at point of sale. Also, some pesticides are only poisonous to the pest they have been developed to resist, and have little impact on the human body.

It’s also important to understand that the human body has learnt to cope with small amounts of many toxic chemicals produced by the plants we eat: these chemicals are produced by plants as their own natural defense system against many insect and parasitic pests.

Further Reading

Ø       World Cancer Research Fund Report (1997), “Food, Nutrition and the Prevention of Cancer”

Ø       World Health Organisation (2002) Diet, Nutrition and the Prevention of Chronic disease Tech Report Series No. 916.

Ø       AFIC  Short Briefing on Pesticides Residues www.afic.org/