Michael Clapham

Phenolic composition and antioxidant capacity of a novel variety of purple potato

There is a growing awareness of the potential health benefit of diets rich in fruits and vegetables and nutritional guidelines indicate that an increase in their consumption may reduce the risk of CVD and certain cancers . This effect has been ascribed in part to low molecular weight phenolic compounds which can act as antioxidants due to their extensive conjugated πelectron systems which allow ready donation of electrons or hydrogen atoms from their hydroxyl moieties to free radicals (2). Potatoes (Solanum tuberosum L) provide a rich and varied source of micronutrients in the human diet, >80% of the UK population consume potatoes on a weekly basis. A novel purple potato, Purple Majesty has been introduced to the UK market by Albert Bartlett. Anthocyanins are the most abundant phenolic present in purple potatoes and there is some evidence that they are able to elicit endothelium dependent vasorelaxation and may be protective against CVD . The aims of this study were to investigate the antioxidant potential of purple potatoes compared with white potatoes, to establish the effect of domestic processing on phenolic composition and antioxidant capacity and to compare the findings with other vegetable sources to establish whether purple potatoes could provide a rich source of antioxidants in the human diet. Purple potatoes contained higher overall levels of total phenolics and anthocyanins and had a greater antioxidant capacity compared with white potatoes. Domestic processing significantly reduced the total phenolic content of purple potatoes (p=0.0004) but did not influence anthocyanins or the overall antioxidant capacity. In conclusion, cooked purple potatoes contain significantly higher antioxidant capacities than cooked white potatoes (p=0.0001). Purple potatoes could provide a rich source of antioxidants in the UK diet and they compare favourably to other ‘purple vegetables’ for example in this study, purple potatoes contained 105.5 mg GAE/100g Fresh Weight compared to Red cabbage, 439 mg GAE/100g Fresh Weight.

Assessing the validity and acceptability of DietPhone as a dietary measurement tool in adolescent girls

Introduction Dietary assessment is essential for investigating the relationship between diet and disease. Previously it has been assumed that dietary measures used in adults were appropriate in younger age groups. However research has highlighted that measuring the diets of adolescents in particular, poses unique challenges (Livingstone et al, 2004). It has been suggested the development of new and innovative techniques for obtaining dietary intakes of adolescents could improve the accuracy of reporting in this age group. This study aims to investigate whether DietPhone is a valid dietary assessment tool and whether it is acceptable to use with adolescents. Methods Eleven third year girls were required to keep a five day dietary record using both diet diaries and DietPhone over separate time periods. Comparisons of the mean daily intakes of energy, protein, carbohydrate, total fat and calcium were made between the two methods. Using the Bland & Altman technique, the level of agreement between the two methods was determined. Additionally focus groups were carried out to establish whether this group found DietPhone to be acceptable to use. Results At the group level, analysis revealed good agreement between the two methods for carbohydrate, with a mean difference of 15.9g being observed. However there appears to be a lack of agreement for intakes of energy, protein, total fat and calcium, with mean differences of 169kcal, 9.3g, 8.3g and 72mg respectively. Furthermore wide limits of agreement were observed for all the nutritional parameters measured, suggesting a lack of agreement at the individual level. Nevertheless DietPhone was established as the preferred method of choice during the focus groups. In addition the group identified several modifications that could ultimately improve DietPhone. Conclusion Due to the lack of agreement observed between the two methods, it is not appropriate to recommend replacing diet diaries with DietPhone as a dietary assessment tool at this time. However it appears that participants enjoyed using DietPhone and it was favoured over using diet diaries, suggesting this technology is acceptable to use with this population. Therefore in the future, DietPhone has the potential to improve the accuracy of dietary assessment in adolescents.

The adequacy of long-chain n-3 fatty acid intakes in primary schoolchildren

By JM McKENZIE, MC CLAPHAM, and A MacGREGOR. Queen Margaret University, Edinburgh, Scotland, EH21 6UU Long-chain omega-3 polyunsaturated fatty acids (LC n-3 PUFA), particularly eicosapentanoic acid (EPA), and dococosahexanoic acid (DHA), play an important role in neurological and cognitive development in children (1) . Recent evidence suggests that the in vivo synthesis of these LC n-3 PUFA from α-linolenic acid (ALA) is less efficient than previously thought, which puts into question the adequacy of dietary intakes based on the conversion of ALA. Although sources of ALA can be found throughout the diet, intakes of preformed LC n-3 PUFA are restricted to relatively few, less commonly eaten foods, such as oily fish. In response, food producers have developed innovative approaches to increasing dietary intakes of LC n-3 PUFA, targeting many of these foods at parents by implying benefits in children’s learning and behaviour. There is currently no information available on the current intake of LC n-3 PUFA in children and no validated method of collecting intake data. The aim of this study was to assess the total intake of n-3 PUFA, with determination of the contributions of ALA, EPA, and DHA, in children aged 5-8 years old, using a food frequency questionnaire (FFQ), developed to incorporate both traditional and newly developed food products assumed to contribute to dietary intakes of n-3 PUFA’s. When compared against the DRV minimum recommendation for total n-3 PUFA, 0.2% of total energy (2) , intakes in females were significantly greater (n=22, p=0.007), however, intakes in males were not significantly different (n=11, p=0.184). Intakes of total LC n-3 PUFA appeared to be significantly lower that recommendations of 0.45g/day (3) (p<0.0005 for both males and females). This study indicates that despite the adequacy of dietary intakes of total n-3 PUFA in children, intakes of LC n-3 PUFA may be lower than the recommendations. Intakes of total n-3 PUFA, predominantly from ALA, were, however, significantly lower than the intakes reported in the National Diet and Nutrition Survey (4) (p<0.0005 for both males and females) indicating that the use of this FFQ to estimate n-3 PUFA intakes requires further validation.