No available dietary assessment method is without error in measuring dietary intake. This has led to an increased interest in biological markers of dietary intake. This article is a review of the literature investigating whether the concentration of carotenoids in blood can serve as biological markers for the intake of fruit and vegetables. The literature indicates an association between intake of fruit and vegetables and the concentration of total carotenoids, alfa-carotene, beta-carotene, lutein and beta-cryptoxanthin in plasma. The same association was not observed for plasma lycopene. Results from several studies also indicate that plasma alfa-carotene and plasma total carotenoids are more suitable as biological markers of the intake of fruit and vegetables than the other carotenoids. As there are large individual variations in the plasma carotenoid response after intake, carotenoids in blood will be a better marker of intake at group level than individual level. Furthermore, the average value from several measurements of carotenoids in blood will be a better marker of long-term intake than a single measurement. Several factors in addition to fruit and vegetables influence the concentration of carotenoids in blood. It is important to assess these factors when carotenoids in blood are used as biological markers of the intake of fruit and vegetables.
Recent research has documented that a high intake of vegetables and fruits reduces the risk of cancer in the mouth and pharynx, larynx, oesophagus, lung, stomach, pancreas, breast and bladder. A large intake of salt increases the risk of cancer in the stomach, and a large intake of red meat increases the risk of cancer in the colon and rectum. Furthermore, the studies demonstrate that regular physical activity reduces the risk of cancer in colon, and that obesity (BMI > 30) increases the risk of cancer in the endometrium, breast and kidney. There is also evidence for increased cancer risk in the mouth and pharynx, larynx, oesophagus, liver, colon, rectum and breast from high alcohol intake. It has been calculated that a 65% increase of the intake of vegetables and fruits will reduce the incidence of cancer by about 23% or about 4,000 cases in Norway every year. It is also estimated that recommended diets, together with maintenance of physical activity and appropriate body mass, can reduce cancer incidence by 30-40%.
BACKGROUND: We present a survey of the intake of fruit and vegetables among Norwegian children and adolescents and examine the association between fruit and vegetable intake and intake of macronutrients and micronutrients. MATERIAL AND METHODS: In 2000 and 2001, a nationwide dietary survey using four-days records was conducted among four-year-olds and students in the fourth and eighth grades (UNGKOST-2000). RESULTS: The average intake of fruit and vegetables was nearly 250 gram per day, increasing with age. The percentages of children eating more than 500 gram fruit and vegetables per day were 5% among the four-year-olds, 7% among fourth-graders, and 11% among eighth-graders. A positive association was observed between intake of fruit and vegetables and intake of fibre and all micronutrients, while a negative association was found between fruit and vegetable intake and percentage of energy coming from added sugar and saturated fatty acids. INTERPRETATION: The study shows that children and adolescents have less than half the recommended intake of fruit and vegetables. Furthermore, higher intake of fruit and vegetables is associated with higher dietary quality.
The purpose of the study was to investigate the consumption of fruit and vegetables among boys and girls in a teenage cohort with respect to changes, gender differences and stability of consumption over time. In 1990, a representative sample of 13-year-olds from Hordaland county was recruited (n = 924) and surveyed regularly until the age of 19. The frequency of consumption decreased dramatically from the age of 13 to the age of 19. At the age of 13, 57% reported eating fruit daily, whereas only 21% of the boys and 37% of the girls reported eating fruit daily at the age of 19. Corresponding results for the consumption of vegetables showed that 42% reported eating vegetables daily at the age of 13, compared to 29% at the age of 19. No clear gender differences were found. The consumption frequency at group level at the age of 13 was a good indicator of the consumption frequency at a later age during adolescence. While younger adolescents until now have been at the focus of campaigns aimed at increasing fruit and vegetable consumption, our results point to the importance of focusing also on the older adolescents.