The Pharmaceutical Journal
Vol 270 No 7233 p133
25 January 2003

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Nutrition and health conference

Nutrition messages must be simplified and healthy foods made easily available

In the keynote address, Dr Ian Gibson, vice-chairman, Parliamentary Food and Health Forum Committee, said that Britain was still lingering at the bottom of the league on diet-related disease tables. Obesity was one example, with the number of obese people growing by 1,000 each day. The National Institute for Clinical Excellence (NICE) had estimated that obesity costs the economy £1.9bn and the NHS £0.5bn a year. What is needed is a move away from telling people what to eat and what not to eat towards a more population-based approach to nutrition and health. Nutritional messages have to be simplified and healthy foods brought within the reach of everybody, both financially and geographically.

Diet and cancer

Two speakers updated participants on diet and cancer. Dr Naomi Allen (Oxford University) presented some preliminary results from the European Prospective Investigation into Cancer and Nutrition (EPIC). This is a prospective cohort study of over 500,000 men and women recruited in 10 European countries to investigate the association between diet and cancer risk. Alcohol intake exceeding 60g a day (six pints of beer) or smoking more than 20 cigarettes is associated with a nine-fold risk of upper gastrointestinal cancer, and the two together increase risk by 50-fold. High intake of fruit and vegetables (456g daily) reduces the risk of upper GI cancer by half and colorectal cancer by 26 per cent compared with low intake (287g). However, no links with fruit and vegetables has been shown for prostate cancer, and consumption of tomatoes and tomato sauce is associated with increased risk — a surprising finding given that previous studies have shown reduced risk with tomato products. Dr Allen pointed out that these are preliminary findings, which need to be confirmed.

Professor Timothy Key (University of Oxford) gave an overview of a review on diet and cancer conducted for a new joint World Health Organization/Food and Agricultural Organization of the United Nations report, which will soon be published. Evidence shows that obesity increases the risk for cancers of the oesophagus, colorectum, breast (postmenopausal), endometrium and kidney. Body weight should be maintained in the body mass index range of 18.5–25kg/m2 and weight gain in adulthood should not exceed 5kg, he said. Alcohol causes cancers of the oral cavity, pharynx, oesophagus and liver and causes a small increase in the risk for breast cancer. Consumption of alcoholic beverages should not be recommended and if consumed, intake should not exceed two units a day. Fruit and vegetables probably reduces the risk for cancers of the oral cavity, oesophagus, stomach and colorectum, while preserved meat and red meat probably increase the risk for colorectal cancer. However, not all the data on meat are consistent. In addition, very hot drinks and foods probably increased risk for stomach cancer. Drinks should not be consumed scalding hot, he said.

Diet and cardiovascular disease

An update on the link between nutrition, homocysteine and cardiovascular disease was given by Professor Martijn Katan (Wageningen University, Netherlands). He said it is well established that homocysteine levels could be lowered by folic acid and vitamin B12, but other dietary factors could play a role. One of these is betaine, a methyl donor in the remethylation pathway of homocysteine to methionine. Betaine is used to reduce high levels of homocysteine in patients with hereditary disease of homocysteine metabolism, but its effects in the general population are unclear. Coffee has been linked to high homocysteine levels, but caffeine is not responsible. One of the culprits appears to be chlorogenic acid, a phenolic antioxidant, present in high concentrations in coffee.

Diet and plasma cholesterol

The link between diet and plasma cholesterol has become a controversial subject during recent years, with some experts suggesting that it has such a limited effect in comparison with statins that giving dietary advice is not worthwhile. Professor Tom Sanders (King's College London) said that dietary advice to decrease the intake of saturated fatty acids and lose weight typically only achieves a 5 per cent reduction in plasma cholesterol concentration. However, a combination approach employing advice not only to control weight and decrease saturated fat but also to increase the intake of soluble fibre (eg, oats), to use soy products and oils rich in monounsaturated (eg, olive oil) in moderation combined with the use of phytosterol enriched yoghurts and spreads (eg, Benecol, Flora Pro-Activ) could result in a 20 per cent reduction in plasma cholesterol. Thus, it is possible to decrease the average plasma cholesterol concentration in the middle-aged population from 5.8mmol/L to below 5mmol/L by means of diet.

The Mediterranean diet

Professor Michel de Lorgeril (University of Grenoble, France) said that, for secondary prevention of cardiovascular disease, the focus should not be on serum cholesterol, because this did not improve clinical outcome. Promoting the importance of the Mediterranean diet, he said there is a need to reduce intake of fat and saturated fat, but n-6 polyunsaturated fat should not be increased. Instead, there is a need to emphasise n-3 fatty acids, including the parent compound, alpha linolenic acid (ALA) and the longer chain derivatives — eicosapentaenoic and docosahexaenoic acids.

Is chocolate addictive?

The addictive powers of chocolate was the subject of a presentation by Dr Peter Rogers (University of Bristol). It has been widely speculated that chocolate contains potentially psychoactive substances, including caffeine, theobromine, phenylethylamine, serotonin and tryptophan, which could lead to addiction. However, these compounds do not explain the liking, craving and addiction to chocolate. One study has shown that both milk chocolate, which contains high concentration of these substances, and white chocolate, which contained low concentrations, reduced chocolate craving. Moreover, cocoa drops do not reduce craving, indicating it is the sensory characteristics of the chocolate, not the chemical ingredients, which produce the effect. Craving for chocolate and any other foods could be explained in terms of dietary restraint and concern about weight. In other words, craving, and indeed "moreishness" arise or are exacerbated as a result of attempting not to eat the foods or to restrict the quantities consumed. Chocolate is considered to be a fattening food. Individuals think they should not eat it at all or only in small amounts, but dietary restraint would be followed by an increased urge to eat it. The traditional view that craving is due to an addiction, which leads to blaming of the food in question is not credible, Dr Rogers concluded.