Super-foods (feature article)

[Guest guest]

Eat your veg. It could be the next best thing to giving up smoking

 

Eating the wrong foods could be responsible for up to 30 per cent of

cancers, but there is growing belief that 'superfoods' are the key to

preventing it. Can broccoli really be that good for you? Andrew Purvis

finds out

 

Sunday October 10, 2004

The Observer

 

http://observer.guardian.co.uk/foodmonthly/story/0,9950,1320913,00.html

 

It's an image familiar to every TV viewer - Anthony Hicks, 58, real-life

front man of the Government's Quit Smoking campaign, propped in a

hospital bed with his voicebox removed, eyes sunken, skin the colour of

tobacco smoke, croaking intermittently about plans to spend Christmas

with his daughter. Ten days later, the caption tells us, Anthony is dead

- killed by cancer of the lung and larynx, a compliant victim of his own

smoking habit.

 

There is no ambiguity in the NHS message - and those of us who don't

smoke breathe a sigh of relief (because we can). We walk to the kitchen,

take a ready-made lasagne from the fridge, place it in the microwave; if

we're feeling generous to ourselves, we might fry a fillet steak in a

little butter, eat it (guiltily) with a plateful of oven chips and treat

ourselves to a can of lager and a tub of chocolate chip ice cream.

 

Unwittingly, we are placing ourselves in the same high-risk category as

Anthony - victims not of cigarette smoke but of our Western diet. In its

World Cancer Report, published last year, the World Health Organisation

(WHO) quietly dropped the bombshell that 30 per cent of cancers in the

West can be attributed to dietary factors - placing food second only to

tobacco as a preventable cause of cancer. If we all improved our diet

overnight (dream on), 2.1 million lives a year could be saved. Instead

of 20 million people worldwide suffering from cancer, the figure could

be 14 million (and a further half of those could be avoided by also

banning smoking). Of the 10 million new cases every year, three million

could be prevented by eating wisely.

 

What's more, as Western-style diets take hold in developing countries,

they too are at increased risk of cancer. The evidence, says Sara Hiom,

head of health information at Cancer Research UK, is in various

migration studies conducted with Japanese women, who are prone to far

lower rates of breast cancer than those in the West. 'Within one

generation of migrating to America,' Hiom explains, 'their breast cancer

risk was that of the indigenous population of America.'

 

This and other environmental factors have put us in the grip of a global

cancer epidemic. By 2020, new cases are expected to rise from 10 million

to 15 million a year. Within 20 years, the number of people living with

cancer is projected to increase from 20 million to 30 million. All this

could be prevented, the WHO implies, by giving up our drip-feed of fast,

processed and convenience foods which are high in fat, sugar and salt.

 

Even if we consume none of these, we cannot feel smug. As we unpack our

organic boxes and make our Saturday-morning forays to farmers' markets

in search of free-range poultry, low-fat ostrich steaks and wholemeal

bread, another danger lurks in the drinks cabinet. After obesity (cited

by Cancer Research UK as an 'absolutely cast-iron' cause of the

illness), excess alcohol consumption - defined by the WHO as 'more than

two units a day' - is the biggest risk factor in cancers of the oral

cavity, pharynx, larynx, oesophagus, liver and breast. Anthony Hicks,

heavy smoker, RIP.

 

So there we were worrying about our children's heart disease, stroke and

diabetes as a result of 'the obesity epidemic', when all along cancer

was a cast-iron risk. But what can we feed our ill-fated progeny to

prevent it?

 

In our unhealthy but strangely health-obsessed world, there is no

shortage of suggestions. Broccoli is often cited by nutritionists and

health writers as a kind of wonder vegetable because it contains

vitamins A, C and E - a hat trick of antioxidants, compounds that

'scavenge' free radicals (oxygen particles that can damage body cells

and possibly cause cancer). Butternut squash and sweet potato also score

three out of three and, like most fruits and vegetables pigmented orange

and yellow, are sources of beta-carotene - one of a group of

antioxidants known as carotenoids. In fact, the body converts

beta-carotene into vitamin A, which is found in green leafy vegetables

among other things.

 

Another carotenoid with potential is lycopene, which is present in

tomatoes. Some studies have suggested it may reduce the risk of prostate

cancer. Tomatoes contain vitamin A and vitamin C as well, making them a

doubly valuable addition to the arsenal. If your children can't stand

fresh tomatoes, though, don't worry: several studies have shown that the

processing of tomatoes makes lycopene more readily available for the

body to use, so ketchup, tomato sauce and pizza topping (which make up

three-quarters of the lycopene intake of Americans) are just as likely

to prevent cancer.

 

Red peppers are excellent for vitamins A and C, while selenium (a

mineral) is present in many plants, including broccoli, beets, cabbage

and garlic as well as nuts, offal, fish, eggs and poultry. A review

study in 2001 reported that selenium, an essential trace element, is

necessary for the functioning of an enzyme that protects against

oxidative damage to cell structures. In animals, it reduced the

frequency of transplanted tumours and may provide protection in the

later stages of human cancer.

 

Several other plant compounds (phytochemicals) have shown promise in the

fight against cancer, albeit in limited trials in the laboratory and in

animals. Glucosinolates (from cruciferous vegetables such as broccoli,

Brussels sprouts, cabbage and pak choi) confer various health benefits

while indole-3-carbinole, another constituent of these vegetables, has

been shown to prevent colon cancer in mouse models. Flavonoids are

another promising group. Quercetin (found in apples, onions, tea and red

wine) blocks the hormone activity in human prostate cancer cells, while

allicin (the main ingredient in crushed garlic) has been shown to

inhibit the proliferation of human cancer cells in the colon,

endometrium and breast.

 

In May, a study by Professor Ian Johnson for the Institute of Food

Research found that a substance called allyl-isothiocyanate (AITC) stops

colon cancer cells dividing relentlessly - the mechanism that causes

tumours. AITC - a breakdown compound of sinigrin (found in brassicas

such as broccoli, mustard, cabbage, horseradish, cauliflower, kale and

wasabi) - is produced when particular vegetables are chopped, chewed,

cooked or digested. Unlike chemotherapy drugs, it appears to target

tumour cells without damaging healthy cells.

 

Despite this growing body of research, the World Health Organisation

offers no advice about specific plant foods in its 2003 report. It

simply lists fruits and vegetables - generally - as one dietary factor

that may decrease the risk of cancer of the oral cavity, stomach and

colorectum. Eat plenty of these (as traditional hunter-gatherers did,

consuming more than 800 different plant-based foods on a regular basis)

and you may be protected. It is what is lacking in our food - the

vitamins, minerals, fibre, phytochemicals and micro-nutrients in a

plant-based diet - that counts.

 

But surely working out what we need to eat to boost our chances can't be

rocket science. If we know there are lower incidences of cancer in

certain parts of the world, such as Japan and rural China, we can

monitor what those populations are eating and identify what it is that

we are doing wrong.

 

At the Oxford University laboratories of Cancer Research UK, principal

scientist Professor Tim Key is doing precisely that. 'All our work here

- and cancer epidemiology everywhere - is based on that premise,' he

says. 'The reason we bother doing our work is that cancer rates vary

around the world and have also varied with time in some countries - so

it's clearly not genetics that determine it but something about

lifestyle. Diet is one of the top candidates on the list.'

 

With such a bleak epidemic looming, the subject is being researched with

a vengeance. In one project, Epic (the European Prospective

Investigation into Cancer and Nutrition), scientists are analysing the

food questionnaires of half a million people in 10 European countries to

shed light on the links between diet and long-term health. The results

are due in the next few years. Coordinated by the WHO and supported by

the European Union, Epic is the largest such study ever undertaken - and

Professor Tim Key is principal investigator of the Oxford cohort, a

group of 65,000 human guinea pigs .

 

If anyone can help devise a cancer-busting diet, it is Professor Key -

but his suggestions are conservative to say the least. The risk inherent

in obesity is 'absolutely cast-iron and confirmed to be true', he says.

'For breast cancer in menopausal women in particular, obesity increases

blood levels of oestrogen - and oestrogen is directly linked to breast

cancer risk. The link with alcohol is also confirmed, so keep your

weight down and don't drink too much.'

 

Eating lots of fruit and vegetables (as the WHO suggests) is 'only a

probable', he says, 'and for no specific [plant] food is there

convincing evidence that it's important'. Red meat is under 'serious

investigation', he adds, because 'there is quite a lot of evidence that

high intakes of meat - and it's stronger for processed and preserved

meat than for fresh meat - may increase the risk of large bowel cancer.

It's a hot topic of research.'

 

And what about boosting soya intake and cutting down on dairy products,

like the rural Chinese who are less at risk from breast cancer? Of the

first, he says the evidence 'has not been very strong' while the second

is 'an interesting area'. I mention Professor Jane Plant's book Your

Life in Your Hands, in which she puts forward a persuasive argument that

giving up dairy produce helped her survive five diagnoses of breast

cancer, but Professor Key is not convinced. 'In less developed countries

where there isn't much food around,' he says, 'women start menstruating

at a late age, they have several children and breastfeed them for a long

time. These factors are all known to reduce breast cancer risk.

Worldwide variation is not just to do with diet.'

 

It isn't the Holy Grail I am looking for, and I begin to wonder about

all those cancer-busting carotenoids, flavonoids and phytochemicals

cited by health writers and nutritionists. Isn't there a shred of truth

in it? 'Everyone wants to know which fruits and vegetables they should

be eating,' Professor Key acknowledges. 'Is it brassicas, is it garlic?

None of these things are sorted out. Reports in the media and in

scientific journals are usually based on a single study which may

identify an interesting effect in a laboratory - but that doesn't mean

it will work in people. The only scientifically based advice we can give

is: 'Eat a variety of fruits and vegetables, and base your choice on the

ones you like and can afford.'

 

It's good advice, but no good at all to those of us who are indecisive

in the supermarket aisle (or who never look at price labels). But in

California, naturally, the selection of nutritionally perfect fruit and

veg has been perfected as a science. David Heber, MD, a scientist at the

UCLA Center for Human Nutrition in Los Angeles, has devised a formula to

help consumers with the weekly shop. In his review article 'Vegetables,

fruits and phytoestrogens in the prevention of disease' (published in

the Journal of Postgraduate Medicine ), he divides foods into seven

colour categories and suggests we eat one type from each group every day

- red (tomatoes and related products), red/purple (berries, grapes, red

wine), orange (carrots, mangoes, pumpkin), orange/yellow (cantaloupe,

peaches, oranges, papaya), yellow/green (spinach, avocado, honeydew),

green (broccoli, cabbage, cauliflower) and white/green (leeks, onion,

garlic, chives).

 

Apart from the red wine (presumably less than two glasses a day), it is

not so different from the superfoods programme outlined by Dr Steven

Pratt, a Californian plastic surgeon, in his book, Superfoods: Fourteen

Foods That Will Change Your Life. It recommends a diet of 14 colourful

foods (such as broccoli, tomatoes, pumpkin, soy, spinach, wild salmon,

oranges and black tea) containing the range of nutrients we need. Though

mainly for weight loss, the diet 'can change the course of your

biochemistry', Dr Pratt claims. 'These foods can help stop the cellular

damage that can develop into disease,' he says - an optimism shared by

Katherine Tallmadge of the British Dietetic Association. 'The reasoning

sounds good,' she says. 'These are the kinds of healthy wholefoods we

should be eating.'

 

The truth is, few of us will heed this advice, somehow believing that

cancer will strike elsewhere - and in the distant future. We have

organic muesli for breakfast, we eat up our greens (once or twice a

week). Why should it happen to us? For one group of people, however, the

link between cancer and diet is real. Already diagnosed, often with

weeks or months to live, they will seize dietary advice with both hands

because it may prevent secondary tumours occurring and brace their

immune systems for the toxic onslaught of orthodox chemotherapy.

 

Michele Eve, 40, a mother of three living in Bristol, was diagnosed with

breast cancer four years ago this month and immediately went on a

cancer-busting diet. She was not prepared to wait for the randomised,

double-blind placebo trials of over-cautious scientists to tell her what

she should be eating.

 

'I was in a bookshop,' she says, 'and the first book I picked up was

about the Bristol Cancer Help Centre. I just feel so lucky that it's in

my home town.'

 

While undergoing chemotherapy ('I was very ill indeed,' she says) and

eventually surgery, Michele adopted the lifestyle changes recommended by

the holistic charity. In addition to counselling and complementary

therapies (including shiatsu, meditation and spiritual healing), these

involved switching to a plant-based, wholefood diet with lots of fruit

and vegetables, pulses and whole grains but very little meat and dairy

produce. 'I gave up fish as well and went completely vegan,' she says,

'though that was my choice.'

 

Four years later (and just one year short of being medically 'clear'),

Michele is completely well - something she attributes both to orthodox

treatment and the Bristol approach. 'When they took the lump out, the

specialist couldn't believe it,' she says. 'All the cancer cells had

gone - which is very unusual. He seemed amazed, but I wasn't. I think

the diet helped me fight the cancer and it was the one thing I could do

something about immediately when everything else was up in the air. When

given a 50:50 chance, you ask yourself " Which half am I going to be in,

then? " You can make a choice.'

 

On a damp, doleful September day, I make my way to Bristol and find the

reception area of the Bristol Cancer Help Centre suffused with natural

light. There is something about the tall windows, high ceilings and

minimalist decor of the former convent that makes it seem sunnier

indoors than out - and when I peer into the relaxation room, where

participants in a five-day residential course are sharing their

experiences of cancer, I notice they are sitting not on polypropylene

chairs (standard issue in institutions) but reclining sun loungers

arranged like radiating spokes around a nutrition therapist.

 

'Would you like a drink?' asks Clare Ben jamin, who has invited me here

to find out about Michele Eve's diet.

 

'A coffee would be nice,' I say, but the request is met with an

apologetic smile and a tray of herbal teas.

 

At once I am reminded of the lack of consensus when it comes to treating

cancer with diet. In the best-known and most controversial approach,

Gerson therapy (invented by German-born doctor Max Gerson in the

Thirties), coffee is the very thing that is believed to work - albeit

administered by enema rather than bone-china cup. When combined with a

strict nutritional regime - principally 13 glasses of fruit juice a day

and injections of vitamin B12 and liver extract - coffee is said to

dilate the bile ducts in the liver and help it excrete cancer-causing

toxins.

 

In June, Prince Charles provoked a venomous attack by the medical

establishment for suggesting Gerson therapy had worked for a cancer

sufferer he knew and merited further research. 'I have no time at all

for " alternative " therapy that places itself above the laws of

evidence,' blustered Professor Michael Baum of University College

London. 'The power of my authority comes with a knowledge built on 40

years of study and 25 years of active involvement in cancer. Your power

and authority rest on an accident of birth.'

 

Professor Karol Sikora, Britain's most eminent cancer specialist, was

equally damning of the diet, saying there was no rationale for it. 'Why

would a coffee enema work?' he asked. 'It's popular at the higher end of

the middle classes, partly because it's expensive and there's an element

of religious mania to it. But the idea that huge amounts of vitamin C

can cure you of cancer is wrong.'

 

Yet here at the Bristol Cancer Help Centre (where sufferers are urged to

take supplements of 500-2,000mg of vitamin C a day, in addition to seven

or more portions of fruit and vegetables), Professor Sikora is an ally.

Visit the centre's website and there he is in his lilac shirt, clashing

tie and serious spectacles, saying: 'Bristol represents the gold

standard for complementary care in cancer.' Climbing the stairs, I pause

on the landing beneath a portrait of HRH, the centre's patron. Somehow,

the Bristol Approach satisfies both sides in a polarised and very angry

debate. When I ask even the most conservative cancer specialists about

the centre's dietary advice, nobody is prepared to knock it.

 

'Well, we're not exactly making people eat live lizards,' says Jane Sen,

the professional chef and cookery writer who helped devise the Bristol

guidelines. Looking at our lunch menu, chalked on a blackboard in the

award-winning restaurant (the centre was named Caterer of the Year in

2000 by BBC Radio 4's Food programme), I can see what she means. I'm not

a great fan of soybean curd, but Malay-spiced tofu with aubergine,

mustard-seed rice, sesame stir-fried broccoli, red pepper, spinach and

sprout salad doesn't sound bad, even when lightly drizzled with peanut

vinaigrette. I ask Jane Sen what is so cancer-busting about it.

 

'The colour is important,' she insists, 'because a colourful plateful

[green broccoli, bright red peppers] means you are eating a variety of

ingredients and getting all the plant nutrients you need. Make sure you

have something raw in every meal [like the shredded spinach in this one]

because raw food still has all its vital energy.' Sprouting seeds should

be consumed three times a week, she says, because they are 'the freshest

things you can eat', with a raised nutritional value. 'Think of all the

energy needed for a tiny thing like that to grow to such a height.'

 

Somehow, it sounds right - but it's hardly Professor Baum's kind of

science. What I am after is a forensic breakdown of the meal's active

ingredients. How does each one fight or prevent cancer - and are any of

the alleged benefits scientifically plausible? In its factsheet 'The

scientific basis for the Bristol approach to cancer care', the centre

offers a few clues. Soya products (such as the Malay-spiced tofu I am

eating) are listed along with six other foods and micro-nutrients that

are 'known to be actively beneficial in cancer prevention and reduced

recurrence': they are cruciferous vegetables (such as broc coli),

tomatoes, onions, garlic, omega-3 fish oils and the mineral selenium.

 

However, when I run this list past Liz Butler, the nutritional therapist

at the Bristol Cancer Help Centre, she is more circumspect than the

promotional literature. 'Tomatoes are a source of lycopene,' she says,

'but lycopene is not a magic bullet like a drug. There has to be a

balance of things in the diet; if you look at one antioxidant in

isolation, you're just messing about.' It's the range and variety of

micro-nutrients that counts, she explains, and the way these compounds

work 'synergistically'. In one study conducted for the Institute of Food

Research, due to be published shortly, anti-cancer agents were found to

be up to 13 times more effective when several foods in a wholefood diet

were combined.

 

The best approach, say Bristol nutritionists, is to eat lots of plant

foods with known benefits for general health (not just those that may

protect against cancer), with an emphasis on 'adding foods to the diet'

rather than subtracting them - the opposite principle to most diets.

 

One controversial addition is supplements in capsule form, since most

experts say a balanced diet delivers all the vitamins and minerals we

need, and the approach has even been linked to an increased risk of

cancer. Beta-carotene supplements (which are recommended on the Bristol

programme) slightly increased the risks of recurrence in a trial

involving people with lung cancer, and another study showed that high

vitamin C intake interfered with apoptosis - the natural cell death that

stops tumours occurring. 'We recommend supplements because people who

are ill, fatigued or busy may not get an ideal diet every day,' Liz

Butler explains. 'There is also evidence that minerals in crops are

declining due to intensive farming.'

 

Cancer sufferers are also advised to cut down on foods 'associated with

an increased risk of cancer'. These include red meat, dairy products,

smoked and salt-cured foods, refined sugars, processed foods, caffeine,

alcohol and table salt. Game and poultry should be organic; fish should

be non-farmed and from deep unpolluted waters, and oily fish should be

small varieties such as sardines and pilchards which carry fewer

contaminants. Despite such rigours, hundreds of people passing through

the Bristol centre say they have benefited from the guidelines while on

courses - and 92 per cent continue to follow them at home.

 

So, does the Bristol approach - and Jane Sen's diet - stand up to

scientific scrutiny? The only study that has ever looked at the outcome

of Bristol patients compared to others (published in the Lancet in

September 1990) concluded that women with breast cancer who had attended

the centre fared worse - though campaigners and scientists later argued

that the study was flawed. When I ask if the centre keeps its own

records of recovery and mortality rates, the answer is no. However, yet

another supportive clarion call comes from Professor Karol Sikura.

Patients on the Bristol programme show fewer side effects during

chemotherapy, he says - an idea that comes as no surprise to nutritional

therapist Liz Butler. 'The rationale behind everything we do is

restoring people's biochemical balance,' she says. 'Then, their immune

system is running well and they benefit more from their conventional

medical treatment.'

 

In the fight against cancer, then, the message is clear: legitimate

science is leading us inexorably towards a vegan diet. Last year, the

WHO made its statement about fruit and vegetables. In March, the Food

Standards Agency published the results of research it had funded into

the link between colorectal cancer and red meat. 'The results support

other published studies showing that higher levels of red meat

consumption increase the risk,' it concluded.

 

With dairy products, too, there is mounting evidence that avoiding them

may reduce the risk of breast cancer. Though cautious about Professor

Jane Plant's reasoning in Your Life in Your Hands (in which she

attributes her own recovery to abstinence), Professor Tim Key at the

Epic project confirms that part of her argument is correct. 'It relates

to a hormone called insulin-like growth factor 1 (or IGF-1),' he says,

'and there is some evidence that if you eat more dairy products, blood

levels of this hormone go up. There is also some evidence that women

with high blood levels of this hormone are more likely to get breast

cancer. So that is quite a tantalising story.'

 

Three months ago, the Lancet concluded that there probably was an

association between animal products and some forms of cancer and further

studies will be published soon, Professor Key reports. 'In fact, we've

been working on that here and have shown that vegans have low levels of

this hormone - and they don't eat any dairy products.' Yet, in his

ruthlessly reductionist way, the principal investigator for Epic-Oxford

says the link between dairy products and cancer is 'not an established

fact'. In terms of advising the public, he concludes, 'the truth is that

we don't know. Some studies have shown the reverse. However, if people

want to take a gamble and say, " I'll give up dairy products because it

might turn out to be true " , fair enough.'

 

It doesn't sound like a gamble to me.