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Updated 08 March 2013

Fruit & veggies: super foods

A news report that fruit and vegetables provide little protection against cancer, should be no excuse to stop eating them. DietDoc explains why fruit and veg remain super foods.

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Last week HealthDay News published an article on “Fruits, Veggies Have Modest Effect on Cancer Risk - Researchers Conclude that the Link is Weak”.

Knowing the public, I can just hear people say: “Thank goodness, now I don’t need to eat fruit and veggies any more!”. This type of reaction is probably rather common in South Africa, where large sectors of the population only like eating starches and meat, and regard fruit and veggies as “Rabbit food!”.

Because it is important to understand that human beings don’t eat specific foods like fruit and veggies for only one reason, I would like to discuss the findings of the study that has caused the anti-fruit and veggie reaction, as well as reasons why these results do not mean that we now don’t need to include fruit and veggies in our diets anymore.

What the study found

According to the report in HealthDay News, US researchers analysed data from more than 470 000 people of both sexes in 10 European countries to determine if eating fruits and vegetables does, or does not protect against cancer.

The results of this "meta-analysis" indicated that there is only a weak link between high intakes of fruits and vegetables and a reduced cancer risk. However when the researchers specifically looked at cancers associated with smoking and drinking, they found a “somewhat reduced risk” for heavy drinkers who ate plenty of fruits and vegetables.

Dr Walter Willett, from the Harvard School of Public Health, who wrote an accompanying editorial, pointed out that “future research should focus on the potential cancer-reducing benefits of specific types of fruits and vegetables, and on the effects of fruit and vegetable consumption early in life".

I can understand where Dr Willett is going with his editorial seeing that I have 2 brochures published by CANSA in my office that are based on Willett’s research into the protective effects of dietary factors and lycopene in particular (which is found in fresh tomatoes and processed tomato products such as tomato puree and sauce) on prostate and other cancers (CANSA, 1999; Willett, 1999).

It is, therefore, not yet a forgone conclusion that human beings don’t need to eat fruits and vegetables.

It is also totally shortsighted to stop eating fruits and vegetables because of the results of this study. Fruits and vegetables have so many other important roles to play in the human diet that cutting them out, would leave us exposed to many other risks.

5 Good Reasons for Continuing to Eat Fruits and Vegetables

1) Variety

The first, and most important South African Food-Based Dietary Guideline (FBDG) states “Enjoy a variety of foods”.

The motivation for this FBDG is that people who have a varied diet are more likely to have a high intake of protective nutrients that will contribute to overall health. Fruits and vegetables are available in such profusion that they are ideal for adding variety to the diet. Just think, there are only 4 types of red meat available (beef, lamb, pork, venison), but just one family of vegetables or fruit can have 5 or more varieties (i.e. the cabbage or Brassica family includes broccoli, cabbage, Chinese cabbage, cauliflower, Brussels sprouts, and the citrus family contains oranges, lemons, limes, grapefruit, naartjies, tangelos and kumquats).

2) High fibre content

Foods with a high fibre content assist digestion and prevent constipation, which seems to be a major problem in modern life, particularly in women. Fresh and especially dried fruit, and most vegetables have a moderate to high dietary fibre content and can help to ensure regularity without having to resort to using harsh laxatives which damage the normal peristalsis of the digestive tract.

3) Low Glycaemic Index (GI)

Most vegetables and many fruits (especially deciduous and citrus fruits) have a low GI and are essential components for low-GI diets that help individuals with type 2 diabetes, PCOS, hypoglycaemia, and insulin resistance to stabilise their blood sugar and insulin levels and to lose weight.

4) Low Fat Content

Most fruits and vegetables have a very low or low fat content, which makes them ideal for inclusion in slimming diets to lower daily energy intake. In addition, most of the so-called “Negative Energy Foods” are vegetables or fruit (e.g. lettuce, cucumber, watercress, berry fruits, citrus, etc), which when included in a slimming diet will help to reduce the energy content of the diet.

The low or very low fat contents of fruits and vegetables also make them good foods for patients who need to reduce their fat intake (hypercholesterolaemia, gallbladder disease, etc).

5) Protective Nutrients, especially Vitamin C

According to the HealthDay report (2010), the protective nutrients found in fruit and veggies did not reduce the incidence of cancers in the meta-analysis performed by the US researchers.

It is, however, a fact that fruits and vegetables contain a large number of protective nutrients such as vitamins, minerals, so-called phytonutrients and dietary fibre.

Take Vitamin C as an example: Ironically we human beings, together with the fruit bat and guinea pigs, have lost the ability to manufacture our own vitamin C. These three species are dependent on dietary sources for their daily supply of vitamin C or ascorbic acid.

We all know what diets without fresh fruit and vegetables did to the sailors in days of yore who developed scurvy. Their teeth fell out, their gums bled and they succumbed to a variety of diseases caused by the lack of vitamin C. As soon as the British Navy made it mandatory for each crewman to receive a serving of lime juice (brimming with vitamin C) every day, the British Navy was no longer plagued by scurvy and their sailors were a lot healthier, which may just have been one factor that contributed to the success of the British Navy in days gone by.

So while the latest meta-analysis shows that eating fruits and vegetables may not protect us against certain cancers, there are still many good reasons for including these super foods in your daily diet.

Fruit and Veggies Rule!

(References: HealthDay News (2010). Fruits, Veggies Have Modest Effect on Cancer Risk. Tuesday, 6 April 2010; CANSA (1999). Health, Tomatoes & Lycopene. Information brochure written by Dr C Albrecht & published by CANSA; Willett WC (1999). Diet & Cancer. Information brochure published by CANSA.)

Any questions? Ask DietDoc

Read more:

The A-Z of Fruit and Vegetables
Top 10 super foods
Fruit and veg fight cancer

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Dr Ingrid van Heerden is a registered dietician and holds a doctoral degree in Nutrition and Biochemistry. She believes that "we are what we eat" and offers free nutrition and weight loss advice via her DietDoc service on Health24.com. Read more of her articles.

 
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