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by the way it s washed. Supermarkets are very conscious of the
possibility of food-poisoning from packaged salad. Because salads
are typically neither cooked nor washed by consumers, they have
to be free from contamination if they are not to cause outbreaks
of E. coli or salmonella illnesses. Rather than take any risk of
causing such an outbreak, supermarkets insist that their salads
are carefully washed in what is effectively disinfectant. Accord-
ing to one food company boss, salads are typically soaked in a
bath which contains 50mg of chlorine in every litre of water
that s twenty times the concentration of chlorine in an average
swimming pool. Whether this heavy chlorination does anyone
any harm no one knows, but many people think it at least kills
some of the salad s taste.
146 " 101 FACTS YOU SHOULD KNOW ABOUT FOOD
79. The best way to stay young may be to eat less
t remains a controversial idea, but there is an increasing
Iamount of evidence for the idea that eating less may be the
most effective way to slow down ageing. The idea is that high-
energy foods make the body burn out faster. By reducing the
energy content of your diet, you let your body function more
gently and more sustainably.
Scientists are not sure how caloric restriction works, but
experiments on mice show that it does. One recent study at
Southern Illinois University showed that restricting calories has
a similar effect on the body to knocking out the effect of growth
hormones. The key seems to be insulin. Feed the body continu-
ally with a high-sugar diet and it adjusts by becoming less
sensitive to insulin. Low insulin sensitivity means body cells
begin to starve themselves of sugar (see Fact 49).
Moreover, some scientists believe that a high-energy diet,
particularly an HFS (high-fat, high-sugar) diet typical of what
we call junk food, helps generate chemicals in the body called
free radicals. Free radicals play a key role in the ageing process by
damaging cell membranes, proteins and DNA, the cell s master
chemicals, through a process called oxidation (not dissimilar to
rusting of metals). There is increasing evidence that restricting
your calorie intake cuts the damage done by free radicals.
Interestingly, recent research suggests that a calorie-restricted
diet could actually promote the growth of brain cells. This is
because the lack of calories seems to put the brain under mild
stress and stimulates cells to release a chemical called brain-
101 FACTS YOU SHOULD KNOW ABOUT FOOD " 147
derived neurotrophic factor (BDNF). BDNF is thought to be impor-
tant in encouraging neurons to grow and make new connections.
Although the whole idea of caloric restriction is highly con-
troversial, many experts now agree that most people can afford
to cut down on their carbohydrate intake. It also makes sense to
cut down on simple sugary food, especially refined sugar, and eat
a balance of more complex carbohydrates, found in foods such
as wholemeal bread, pasta, vegetables, pulses, brown rice and
other grains. These are broken down in the body into glucose
and other simple sugars slowly and steadily, to be used only as
and when required.
148 " 101 FACTS YOU SHOULD KNOW ABOUT FOOD
80. The first GM food product was the Flavr-Savr
tomato, which went on sale in 1994
he problem with tomatoes is that they go soft very quickly
Tafter they ripen. So normally, tomatoes are picked while they
are still green. With luck, they will be ripe by the time they get
to the shops, but by then they will have a very short shelf-life. In
the early 1990s, scientists at the Californian biotech company
Calgene realised that they go soft because of an enzyme called
polygalacturonase (PG). The PG enzyme is released when the
tomato ripens and softens it by breaking down cell walls. The
Calgene scientists realised that if they could knock out the gene
for the enzyme, they could make the tomato stay firm longer.
They worked out that by inserting a back-to-front copy of the
PG gene into the tomato s DNA, they could neutralise it. When-
ever the tomato made RNA copies of the PG gene, it would also
make copies of the back-to-front gene. The PG RNA would then
become entangled with the back-to-front PG RNA and so stop
working. With this modification, the Flavr-Savr tomato could be
left on the vine until it was perfectly ripe. It would still be ripe
and fresh when it reached the shops.
The technology was very clever. Unfortunately, Calgene had
made one fatal error. The strain of tomato they had chosen to
modify was one of the most bland and tasteless. So although
the Flavr-Savr was in wonderful condition when it was sold, it
had no flavour to savour, and no one actually wanted to buy it.
The Flavr-Savr was launched in America with a media flurry
as a scientific breakthrough. Not long after, it was quietly with-
101 FACTS YOU SHOULD KNOW ABOUT FOOD " 149
drawn as a commercial disaster. Naturally, food companies were
wary for some time after of launching GM food products.
Interestingly, about the same time as the Flavr-Savr tomato
was launched, some scientists were thinking of trying to put the
genes of Arctic fish in plants. A fish called the Arctic flounder
survives in icy waters because it makes an oil that stops water in
its body freezing. Some scientists thought that if they could put
the gene for this anti-freeze in plants, they might survive frosts
better. It was only an idea, but newspapers mixed the story up
with the Flavr-Savr tomato. So the myth spread that scientists
were trying to put fish genes in tomatoes. People even began to
think that the tomatoes would taste fishy.
150 " 101 FACTS YOU SHOULD KNOW ABOUT FOOD
81. A number of foods have been labelled
superfoods because of their supposed
health benefits
n 1990, Barbara Griggs and Michael van Straten came up with
Ithe term superfoods . Their idea was that a superfood is one
with functional properties over and above the basic nutritional
minerals and vitamins . In other words, they are suggesting,
certain foods contain special ingredients with health benefits
over and above normal nutrition. Some may slow ageing. Others
may reduce your risk of heart disease. Others may guard against
cancer. And so on.
The idea has really caught on as scientific research focuses on
chemicals in food that have particular effects on the body. The
media love stories about superfoods because they are easy to
understand and generate instant interest as they announce the
latest miraculous research findings. Food retailers love the idea
too, because they can add value to their products by making
health claims about them.
However, many nutritionists are sceptical of the claims. In an
article in Which? magazine, Professor Tom Saunders of London s
King s College points out that 100 years ago digestive biscuits
were being marketed as good for your digestion, while Coca-
Cola was originally marketed as a tonic. He believes that the
health benefits of superfoods are marginal, especially if not
eaten as part of a good, balanced diet.
One of the problems is the speed with which new research is
leaped on without real substantiation. In April 2006, news-
101 FACTS YOU SHOULD KNOW ABOUT FOOD " 151
papers reported that avocados contain chemicals called luteins,
and luteins, it seems, may help prevent your eyesight deteriorat-
ing as you get older. Yet this claim was based on research in
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