Shaping our diet

When I flew over for the annual meeting of the American Association of Cereal Chemists (AACC) in Portland, Oregon at the end of September, I attended a symposium entitled ‘Should grains be the foundation of the Food Guide Pyramid?’. Yes, it sounds dull, but it turned out to be a real eye-opener – showing the new ways in which people are encouraged to eat themselves up over what they eat.

The Food Guide Pyramid (1) is a tool used to promote healthy balanced diets, first launched by the US Department of Agriculture (USDA) Center for Nutrition Policy and Promotion in 1992. It presents a hierarchy of food types, with those at the base making up the foundation of a healthy diet and those at the top representing rich foods to be eaten sparingly. Cereal products, such as bread, pasta or rice, make up the base of the pyramid – recommending that a normal diet would revolve around these food stuffs.

The pyramid is currently under review, with the public consultation phase currently underway. The aim of the renewal process is to update the pyramid in line with current nutritional knowledge, but in the process the Food Guide Pyramid has been opened up to all of today’s uncertainty about what we eat.

Official diet advice has been issued in the USA for around 100 years, mainly with the intention of ensuring that people consume the basic energy and nutritional requirements in order to work and live, which has been particularly important in times of shortage during war or depression. Cereals (principally wheat, but also others such as rice and oats) provide a good source of energy, protein and nutrients in appetising forms, and also lend themselves to being eaten in conjunction with other foods. So they were the natural choice for the basis of a foundation diet.

Over time the problem has been inverted; a relative abundance of food has led to over-consumption being as big a concern as eating too little. In line with this, diet recommendation has changed from being a predominantly technical issue into a social one. The emphasis has changed from recommending a foundation diet that adequately provides the essentials for life, to a total diet that covers everything we eat.

It is one thing to give people access to the food required to live – it is another to make them choose one food item over another. But there is a deeper problem. We now expect our diets to optimise our health rather than to provide what we need to survive. It is in this changing context that the 1992 Food Guide Pyramid (already a guide to a total diet) has taken some undeserved flak (2).

The AACC symposium discussion of whether cereals should still be the foundation of the pyramid follows a number of public health concerns about the consumption of refined cereals. Cereal grains consist of three main parts: the outer layer of bran that protects the grain, the germ from which a new plant would grow, and the endosperm that is an energy store making up the bulk of the grain. During milling, the bran and the germ are separated from the endosperm. Refined flour consists only of the endosperm fraction with some traces of the bran and germ, while whole flour has the bran and germ remixed into the endosperm fraction.

Digestion of the starch in the endosperm can occur much faster if eaten on its own rather than with the bran, which in turn requires the body to produce insulin more rapidly. Researchers have proposed that this is linked to the development of short-sightedness (3), the development of diabetes, and obesity. The bran and germ contain many nutrients and minerals that could promote wellbeing, so these are missed if only the refined section is eaten. Furthermore, the bran is high in fibre, which aids digestion; under-consumption of bran may increase the risk of bowel cancer. One survey suggests that 24,000 lives may be saved each year in the UK if everyone ate a portion of whole grains every day (4).

The 1992 Food Guide Pyramid was based on balancing the intake of foods that people eat. Now there is pressure on the USDA to change the Food Guide Pyramid to stipulate the levels of food that people should eat. At present cereal products in commonly consumed forms compose the foundation of the pyramid, but it is proposed to change this to whole-grain cereal products that people don’t currently eat. Additional pressure comes from alternative pyramids based on foundations which emphasise selected oils (5) or fruits and vegetables (6).

In the light of this evidence, making whole grains the basis of the Food Guide Pyramid appears the sensible option and was the thrust of the AACC symposium. But this would actually represent a significant and detrimental change. Whereas the original purpose of food guides was to propose a healthy diet out of the foods that were available and that people generally wanted to eat, now it is being turned into a prescription of what we should be eating at the expense of what we would prefer.

Take bread, for example, one of the most popular cereal products. It is eaten around the world in many different forms: steamed breads in the Far East, flat breads in the Middle East, sliced loaves in the UK, to name a few. But one thing almost every country has in common is that people prefer their bread to be white. When Portland’s pioneering artisan baker, Greg Mistell, was asked why he doesn’t make more whole-grain breads, he said: ‘Because people don’t buy them.’ In China, flours are sold in various grades based on the endosperm extraction rate, and social status can be derived though being able to purchase the most pure. People just like it that way, and the same is true for pasta, rice and noodles.

Changing the foundation of the Food Guide Pyramid to state explicitly whole grains would require a monumental public health campaign if it is not going to be ignored. The objective of the exercise is changed from providing guidance on how to have a balanced diet to mass re-education. Is this worth it? How can we measure the benefits of eating more whole-grain foods against the pleasure derived from eating refined products?

The benefits of eating refined cereals seem to have been forgotten. Our current diet has developed with standards of living and nutritional advances that have seen the average height in the UK increase by three-quarters of an inch each generation (7), and the average life expectancy of a 65-year-old increase by between four and five years over the past century (8).

At a time when health worries lead the headlines on a weekly, if not daily, basis (as has been previously noted on spiked (9)), such a change to the Food Guide Pyramid will tend to heighten people’s anxiety over what they eat, rather than allow people to relax and actually eat normally. Making a food that few people like to eat the foundation of a recommended normal diet only further mystifies what the ‘normal’ diet is.

It would be better to fend off these criticisms of the original Food Guide Pyramid. This doesn’t mean that we should do nothing to improve our diets, but just to suggest that potential health gains aren’t worth the anxiety that could be created by another public health campaign. Recognising the increased benefits of eating whole grains is valuable; one of the major research themes at my research centre is to develop new techniques for increasing the bran content of breads without undermining the texture, colour and taste. Hopefully, in the future we will all be able to get the benefits of whole grain while still enjoying the foods we like.

Peter Martin is a research associate at the Satake Centre for Grain Process Engineering, at the University of Manchester Institute of Science and Technology (UMIST).

(1) Center for Nutrition Policy and Promotion, US Department of Agriculture

(2) Scales tip in favor of new food pyramid, USA Today, 4 November 2002

(3) Bread blamed for short sight, BBC News, 3 April 2002

(4) Eat whole grain, live longer, BBC News, 21 Februrary 2002

(5) Food Pyramids, Harvard School of Public Health

(6) The California Cuisine Pyramid, UCLA Center for Human Nutrition

(7) Stand up for your height, BBC News, 2 July 2001

(8) Expectation of life at age 65: by sex, 1901 to 2021, Social Trends 33

(9) Shooting the messenger, by Rob Lyons