The role of plant-based foods in the diets of adults (18-90y) in Ireland

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Kent, Gráinne
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University College Cork
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Plant-based (PB) diets are generally associated with good health and environmental sustainability but there is a wide range of PB diet definitions in the literature. PB foods, including ‘fruit & vegetables’ and ‘cereals, grains & potatoes’ provide important nutrients in the diets of adults and are promoted within food-based dietary guidelines (FBDG). The aims of this thesis were to first develop a systematic methodology to identify the PB component of an omnivorous diet using two extremes of PB diet definitions, i.e., plant-based (all) (PB-A): ‘all plant-based foods’ regardless of dietary quality and plant-based (healthful) (PB-H): ‘healthful plant-based foods’ only and then to use this systematic methodology to examine the nutritional quality of the PB component of the diet using the two definitions (PB-A and PB-H) compared to the baseline diet in adults in Ireland. Additionally, this thesis aimed to estimate the current intake of ‘fruit & vegetables’ and ‘cereals, grains & potatoes’ in adults in Ireland, to assess compliance with recommendations and to determine their contribution to overall energy and nutrient intakes. The analyses for this thesis were based on data from the National Adult Nutrition Survey (NANS), a nationally representative cross-sectional study that collected food and beverage consumption data from 1500 adults aged 18-90 years in the Republic of Ireland, between 2008 and 2010. Dietary data were collected using semi-weighed food diaries and nutrient intakes were estimated using UK and Irish food composition data. Mean daily intakes (MDI) of food groups and nutrients were estimated using SPSS©. The nutritional quality of the PB diet components and baseline diet was assessed by estimating energy-adjusted intakes of nutrients. Differences in the MDI of food groups and nutrients between PB diet components were assessed using independent sample t-tests. The percent contribution of food groups to energy and nutrient intakes were calculated by the mean proportion method. A novel 23-step protocol was developed which outlined the exclusion and inclusion criteria for the PB-A and PB-H components of the diet. This methodology was then used to examine the nutritional quality of the PB diet components using the two definitions (PB-A and PB-H) compared to the baseline diet (the overall diet consumed by the NANS population). Compared to the baseline diet, both PB diet components were of better nutritional quality in terms of many nutrients, including total and saturated fat, carbohydrate, dietary fibre, vitamin C, thiamin, folate, sodium, potassium, iron, but of poorer nutritional quality in terms of protein, MUFA, PUFA, total sugars, vitamin D, vitamin B12, calcium and iodine (PB-A only). Compared to the PB-A component, the PB-H component of the diet was of better nutritional quality with regards to total and saturated fat, PUFA, protein, carbohydrate, dietary fibre, free sugars, B-vitamins, vitamin C, potassium and iron but was of poorer quality for vitamin D and vitamin B12. The MDI of ‘fruit & vegetables’ (285g/d; approximately 3.6 servings) was below the World Health Organisation recommendation of ≥400g/d and the Irish FBDG of 5-7 servings/d (≤ 150ml/d from unsweetened fruit juice). Despite low intakes, ‘fruit & vegetables’ made important contributions to intakes of PUFA, carbohydrate, dietary fibre, vitamin C, vitamin A, potassium, folate, vitamin E, magnesium and thiamin, while also contributing to intakes of total sugars and free sugars. The MDI of ‘cereals, grains & potatoes’ was approximately 4.5 servings, however, only 2.1 servings were from ‘wholemeal cereals and breads, potatoes, pasta and rice’, which was below the Irish FBDG recommendation of 3-5 servings/d. ‘Cereals, grains & potatoes’ made significant contributions to intakes of energy, carbohydrate, dietary fibre, protein, folate, thiamin, niacin, vitamin B6, iron, magnesium, calcium, potassium and zinc but also contributed to intakes of sodium and made smaller contributions to the intake of saturated fat and free sugars. The data presented in this study may benefit the scientific community, health professionals, policymakers and the food industry in understanding how intakes of high-quality PB foods can be increased in adults in Ireland in light of the shift towards a more PB diet for health and environmental benefits.
Plant-based , Plant-based diets , Adult diets , Fruit and vegetables , Cereals, grains and potatoes
Kent, G. 2022. The role of plant-based foods in the diets of adults (18-90y) in Ireland. PhD Thesis, University College Cork.
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