The Scientific divide
Text of speech given by ProfessorTom Sanders at the Food Foundation debate.
There is a popular belief that modern food production techniques are responsible for many of the ills of society particularly among the Green Movement, and that we should return to some Tolkeinesque rural idyll where food is produced locally using organic farming methods and that food should be bought in farmer's markets and corner shops. I wish to challenge this view.
- World food production has kept pace with population growth through the adoption of technology developed through scientific discoveries.
- As the world population is forecast to double over the next fifty years, food production must increase in order to meet demands. The challenge for science is to facilitate this.
Nowadays most of the food we consume
- is produced by large farms in a variety of countries
- is processed industrially
- and sold in supermarkets and multinational food outlets
This is termed the globalisation of the food supply.
Urbanisation and then globalisation mean that people no longer depend upon food produced locally.
Trade, foreign travel and migration have resulted in some convergence towards a global diet. Pizza, pasta, burgers-some have called this Cocacolarization and Mcdonaldization of food supply.
But it has also allowed new foods to liven up the British food repertoire. It is worth remembering that until relatively recently British food was feared throughout the world.
Globalisation has increased both the choice and supply of food available. For example, we now enjoy a plentiful supply of fruit and vegetables throughout the year. As a consequence fruit consumption has increased by 50% compared with the 1970s and the average intake of vitamin C is now twice as high, partly owing to the increased consumption of fruit juice.
Globalisation has also enabled ethnic groups to readily obtain foods for their traditional cuisines – for example fresh ingredients to make curries as opposed to curry powder.
Over the past 15 years food retailing has become increasingly centralised with a handful of large supermarkets selling more than 80% of food. This has increased the efficiency of food trade, enabled food to be fresher, decreased food prices relative to total income and improved the variety and quality of food available.
This centralisation of the food supply has also helped to iron out regional differences in food supply in the UK. For example, the major retailers now offer the same choice of products nationwide.
I now want to comment on the impact of these changes on health. The relationship between food intake and health is complex.
- Food can be contaminated and spread infectious disease – indeed in the past TB was spread by milk
- An inadequate food intake results in malnutrition
- But a food intake in excess of energy requirements leads to obesity
- The composition of the diet also seems to be related to risk of heart disease, stroke and cancer which are leading causes of death in the UK and most developed countries
Globalisation means that food can become contaminated in one country and cause outbreaks of foodborne illness in another. This has already happened. In the USA, the import of contaminated strawberries and raspberries from Mexico and Guatemala have led to large outbreaks of hepatitis A and cyclosporiasis.
Centralisation of the food supply presents new opportunities for foodborne illness to infect large numbers of consumers. This has already happened. There are many examples: E.coli 0157, salmonella in eggs and poultry, antibiotic resistant camplylobacter and BSE. In the USA, central contamination of Schwan's ice-cream caused gastoenteritis in 224,000 people.
Globalisation and centralisation necessitate the monitoring of food quality throughout the food chain "from the plough to the plate". This complex process requires a sophisticated infrastructure and thus favours larger companies.
Globalisation has been blamed for the current worldwide epidemic of obesity. "Junk food" high in fat and sugar being the leading culprits. However, rates of obesity are high in the former communist countries such as Russia and Ukraine where so-called junk food consumption is low.
- Last week the National Audit Office reported that one in five people in the UK are obese. The press releases blamed a diet high in fat and sugar along with decreased physical activity.
- here is compelling evidence that physical activity has declined because of an increase in watching television (up to 30 hours a week), sitting in front of a computer and increased use of the car.
- However, there is little evidence that we are eating more calories, fat or sugar. Indeed both household fat and calorie consumption have fallen by 25%. Probably more important is the increase in portion sizes of food eaten outside the home and passive overconsumption such as idle munching of biscuits and snackfoods while watching TV!
- There is a strongly held belief by many dietitians that an increased intake of fruit and vegetables would help the prevent and treat obesity but there is no evidence from controlled studies to support this contention.
There is a simplistic and widely held view that dietary fat increases risk of heart disease. But this is wrong – some of the lowest rates of heart disease recorded in affluent populations are in countries with high intakes of fat, for example Greece and Iceland. It is the type of fat that matters.
The risk of heart disease is increased by a high level of cholesterol in the blood. Saturated fatty acids, found in meat and dairy fat, are known to contribute to raised blood cholesterol levels. The intake of saturated fatty acids has fallen by about 50% over the past 30 years and heart disease has also declined by about one-third.
Recent controlled trials show that further reductions in saturated fatty acid intakes will only lower blood cholesterol by 2-5%. At best this might prevent 5-10% of heart attacks.
There is currently much enthusiasm for fruit and vegetables in the prevention of cardiovascular disease. The Five Alive campaign aims to encourage people to eat five portions of fruit and vegetables a day – about 400g or 1lb a day. Well controlled studies have shown that a balanced diet containing plenty of fruit and vegetables helps to lower blood pressure but that advice to increase fruit and vegetables alone was less effective. Fruit is a good source of vitamin C and vegetables are a good source of some antioxidant vitamins, which were thought to help protect against heart disease. However, recent systematic reviews of all the controlled trials conclude that there is no benefit from an increased intake of vitamin C, betacarotene or vitamin E. At present, no intervention studies have shown any benefit in terms of reduced risk of heart disease from advice to increase fruit and vegetable consumption.
Two large reports published 4-5 years ago by WCRF and the Department of Health suggested that an increased consumption of fruit and vegetables might help prevent cancer. The evidence was based mainly on observational studies and were confounded by tobacco and alcohol intake.
The more recent pooled analysis of all the studies and clinical trials have failed to show that increased fruit and vegetable consumption protects against cancers of the colon and breast when adjustments are made for other lifestyle factors such as smoking and alcohol intake.
Nevertheless, there is mounting evidence that people who avoid fruit and vegetables completely are at increased risk of these cancers. People who avoid fruit and vegetables are not eating a balanced diet.
Government policy on nutrition has been prescriptive and focused on labelling foods as "good" and "bad". "Fatty and sugary foods" are blamed for obesity and "fruit and vegetables" are promoted as a panacea for all ills.
To quote the Secretary of State for Health – Alan Milburn:
"Experts agree that eating fruit and vegetables is the second most effective way to prevent cancer and heart disease after reducing smoking."
I cannot agree with this statement.
The centrepiece of the government Nutrition Policy is The National School Fruit Scheme. This involves giving each child between the age of 4-6 years of age a piece of fruit daily – an apple, a satsuma or a banana. The nutritional contribution this makes to their diet is trivial – an equivalent of 2-5 teaspoons of sugar, 2-4g of fibre and between 5-25mg of vitamin C – a vitamin that is in adequate supply in their diet anyway with over 91% of children aged 4-6 meeting reference nutrient intake. The cost of this scheme is a staggering £52 million. While there may be a case for a smaller scale project targeted at low income groups where fruit is not consumed, this blanket approach is a logistical nightmare and a wasteful use of scarce resources. The utility of this political gesture needs to be questioned.
In conclusion, Mr Chairman, I have tried to outline the scientific divide between the Green Movement and the scientific community. Globalisation and centralisation of the food supply has multiple benefits but also present new threats. People are now living longer between 4-5 years longer than in the 1970s and young people are taller than previous generations which suggest that overall diet has improved. Much of our knowledge concerning food and health is incomplete. However, the best advice at present is to focus on achieving a balanced diet rather than demonizing or promoting certain foods. Nostalgia for some former era needs to be tempered with the knowledge that health and nutritional status was poorer and infectious disease rampant in the past. At a time when we have unravelled many of the secrets of the human genome, we still remain ignorant of the extent to which food effects our health. I would propose that the £52 million which the government is squandering on the School Fruit Scheme would be better invested into human nutrition research to answer these questions.
© Tom Sanders 30 January 2002