Ready to provide concrete dietary advice - Agneta Yngve

Yngve and her research group are studying the correlation between health and our food habits. At the Unit, research is also being conducted into another important public health field, physical activity. The aim of the Unit is to create a more in-depth and detailed knowledge of diet and exercise so as to be able to offer objective, knowledge-based data for advice and recommendations in public health issues.

Yngve's research has largely concerned the eating habits of children and their parents. She led an EU-financed dietary survey, part of the so-called Pro Children project, in nine European countries. The researchers studied how much fruit and vegetables children and their parents eat. The participating countries were Sweden, Belgium, the Netherlands, Denmark, Austria, Iceland, Norway, Portugal and Spain. The data was collected during the autumn of 2003 using a questionnaire which was distributed in selected schools. A total of around 13,000 eleven year-old children and their mothers took part.

The results showed major differences between the countries when it came to how much fruit and vegetables children and their mothers eat. Girls consistently eat more fruit and vegetables than boys. Children in Austria, Denmark and Portugal eat most fruit. Eleven year-olds in Iceland and Spain get the least fruit. When it comes to vegetables, the picture is somewhat different. Children in Portugal, Sweden and Denmark eat the most vegetables; children in Iceland and Spain eat the least. In the Nordic countries, vegetables are mostly eaten raw or in the form of salad. In many other countries, it is more common to have cooked vegetables or vegetables in soups.

"In Sweden, the school lunch contributes a lot to the vegetable intake of eleven year-olds," explains Yngve.

According to this study, the average intake in all coutries fails to reach the amount of fruit and vegetables advocated by the official recommendations for children in each country (recommendations differ between countries). Fewer than half the children reported in the study that they eat fruit and vegetables every day. The average intake of fruit and vegetables varied from 143 grams a day in Iceland to 265 grams a day in Austria and Portugal. In Sweden for example, a daily intake of 500 grams of fruit and vegetables is recommended, not including potatoes.

Nor did the mothers of the eleven year-olds reach the recommended quantities of fruit and vegetables in their diet. There was a clear correlation between the mother's intake and that of the child. Mothers who ate more fruit and vegetables had children who did the same.

The researchers found no correlation between overweight in children and the intake of fruit and vegetables. Such a correlation has been seen in other studies where intake has been followed over time.

"This field requires further research with more thorough methods of measuring eating habits, body fat and weight plus development over time," says Yngve.

With her co-workers in Sweden, she has carried out another study of the eating habits of young people. The study focused on the intake by younger children and teenagers of the important B vitamin, folate (also called folic acid). Folate is necessary to normal cell division in the body. A lack of folate can cause such things as neutral tube defects during foetal development plus anaemia and an increased risk of cardiovascular diseases.

"Since we have no statutory folate enrichment of foods in Sweden, it is especielly important for us to know whether we are getting what we need in our diet."

A total of 692 children and teenagers from Örebro and southern Stockholm took part in the 1998-99 survey. The participants were either 9-10 years of age or 15-16. There dietary intake over 24 hours was recorded using an interview. They also provided blood samples which were analysed for their homocysteine content. The homocysteine content rises in the case of folate deficiency. An elevated value is a risk factor in cardiovascular disease. The researchers also collected details of the older group's school grades. This information was compared with the teenagers' folate intake and homocysteine levels to see if there was a correlation between folate deficiency and poor school performance. The blood tests were also used to find a genetically conditioned metabolic fault which increases the need for folate. This fault occurred in nine percent of the participants in this study and caused a substantial rise in homocysteine level.

The results of this study showed that young people are eating considerably less fruit and vegetables than recommended. The results also showed that many Swedish children and young people are getting small quantities of folate, which is particularly problematic in the genetically compromised group. Particularly amongst the teenagers, there were many with the genetic fault who ate too little folate.

"This is worrying, in regard to such things as future risk of cardiovascular disease and the risk of foetal injuries when the girls get a bit older and want to have children," says Yngve.

The study also showed that folate deficiency can cause poorer school results. The researchers found a correlation between rising homocysteine level (indicating folate deficiency) and falling grade levels in teenagers. This correlation remained even when statistical adjustments were made to remove any effects from the mother's educational level.

"This must be investigated further to see if any other factors can be found to explain the appearance of a correlation between folate status and school performance. But we know that folate is important for normal nerve cell function in the brain and the rest of the central nervous system."

There are only a few vegetables, including legumes, spinach and others with dark leaves which are good sources of folate. Children and teenagers in the study got the greatest quantities of folate from milk and yoghurt.

"If vegetables poor in folate are chosen like cucumber and tomatoes, it does not matter how much vegetables a person eats; they will still have a low folate intake. It is time to try and give more concrete and specific dietary advice."