Ideal dose Ideal dose of protein of protein substitute intake substitute intake

What do protein substitues do What do protein substitues do?  provide 21 amino acids  help growth  lower phenylalanine levels  some provide vitamins and minerals

How much do we give?

School of Thought 1 UK advocate generous quantities of protein substitute

School of Thought 2 children with PKU don’t need big doses of protein substitute

Aim To investigate if a lower dose of protein substitute can achieve the same or better control when compared to the dosage recommended by the UK

Who did we study?  25 children  2-10y (median 6y)  13 girls; 12 boys  dietary treatment: x 50 mg phenylalanine exchanges x 50 mg phenylalanine exchanges - median protein equivalent intake: 2.2 g/kg/day - median protein equivalent intake: 2.2 g/kg/day

Dosages of protein substitute  High dose - 2 g/kg/day protein equivalent - 2 g/kg/day protein equivalent  Low dose g/kg/day protein equivalent

Week 1 Week 2 Week 3 Week 4 Week 5 Week 6 Week 7 7 week study

Week 1 Control normal dose of protein substitute

Week 1 Control 567 morning night day

Week 2 and 3 High

Week 2 and 3 HighLow

Week day Morning Night

Weighed food record

Week 4 and 5 Control normal dose of protein substitute

Week 5 Control 567 morning night

Week 6 and 7 HighLow

Week day Morning Night

Same food menu as week 3

Subject 1 girl 5y 5½exchanges

Subject 2girl 6y6 exchanges

Subject 3girl 7 y7 exchanges

Change in morning blood phenylalanine concentrations

Median change in blood phenylalanine concentrations a.m.p.m.

What are the reasons for differences in change in blood phe levels?  age: no correlation  exchanges: no correlation  PKU mutations  calorie intake

What are the reasons for differences in change in blood phe levels?  age: no correlation  exchanges: no correlation  PKU mutations: coming soon  calorie intake

Reduction in calorie intake

Summary  lower dosages of protein substitute increased plasma phenylalanine concentrations  in some children, it led to very poor phe control  individual differences may be due to severity of PKU  calories contributed by protein substitute is important

Benefits UK  evidence to justify dosage of protein substitute given  important to justify prescription costs None UK countries  should help improve dietary control