MacDonald A, Rylance G, Hall S K, Asplin D, Booth I W
Children's Hospital, Ladywood Middleway, Birmingham.
Arch Dis Child. 1996 May;74(5):412-7. doi: 10.1136/adc.74.5.412.
The optimal dietary management of children with phenylketonuria (PKU) has rarely been rigorously explored. The aim of this study was to assess longitudinally the effects of three factors thought to influence plasma phenylalanine concentrations in PKU: total energy intake; protein intake from natural foods allowed freely in addition to allocated phenylalanine exchanges; and the distribution of protein substitute throughout the day. Nineteen subjects, 15 girls and four boys aged 1-16 years, were enrolled. Food intake was weighed, and twice daily plasma phenylalanine concentrations measured during either 3-day or 4-day periods, for a total of 21 days throughout six months. There was a negative correlation between the percentage of protein substitute eaten by the time of the evening meal and the fall in plasma phenylalanine concentration during the day (r = -0.941; p < 0.0001). On average, 49% of pre-evening meal plasma phenylalanine concentrations were less than 100 mumol/l in children who had taken at least 65% of their protein substitute by the time of their evening meal. There was no correlation between excess natural protein intake from freely allowed foods and (a) pre-breakfast or pre-evening meal plasma phenylalanine concentrations or (b) the daily change between pre-breakfast and pre-evening meal concentrations. Nor was there any correlation between excess natural protein intake on the previous day and plasma phenylalanine concentration on the following morning. Energy intake was not correlated with plasma phenylalanine concentrations. It is therefore preferable to distribute the protein substitute evenly through the day in order to achieve stable phenylalanine concentrations, rather than to carry out further fine manipulation of the phenylalanine intake, which would make management of the diet even more difficult.
苯丙酮尿症（PKU）患儿的最佳饮食管理很少得到严格探究。本研究的目的是纵向评估三个被认为会影响PKU患儿血浆苯丙氨酸浓度的因素：总能量摄入；除分配的苯丙氨酸交换量外可自由摄入的天然食物中的蛋白质摄入量；以及全天蛋白质替代品的分布情况。招募了19名受试者，其中15名女孩和4名男孩，年龄在1至16岁之间。对食物摄入量进行称重，并在3天或4天的时间段内每天测量两次血浆苯丙氨酸浓度，在六个月的时间里共测量21天。晚餐时食用的蛋白质替代品百分比与白天血浆苯丙氨酸浓度的下降之间存在负相关（r = -0.941；p < 0.0001）。平均而言，晚餐时摄入至少65%蛋白质替代品的儿童，晚餐前血浆苯丙氨酸浓度有49%低于100 μmol/l。可自由食用的食物中过量的天然蛋白质摄入量与（a）早餐前或晚餐前血浆苯丙氨酸浓度，或（b）早餐前和晚餐前浓度的每日变化之间均无相关性。前一天过量的天然蛋白质摄入量与次日早晨的血浆苯丙氨酸浓度之间也没有相关性。能量摄入与血浆苯丙氨酸浓度无关。因此，为了实现稳定的苯丙氨酸浓度，最好将蛋白质替代品均匀分布在一天中，而不是对苯丙氨酸摄入量进行进一步精细调整，那样会使饮食管理更加困难。
