Diet prescription - TYR

Establishing a prescription is done in a stepwise manner:

Step 1	Fill the protein (TYR) requirements through the use of measured quantities of natural protein from breast milk, regular infant formula in infants and by natural food intake beyond infancy
Step 2	Fill the protein requirement by adding the TYR/PHE-free L-amino acid supplement that provides a TYR/PHE free mixture of amino acids, and other nutrients
Step 3	Fill energy requirements by adding non-protein calorie sources as needed. Energy needs should be based on ideal body weight whenever possible and are the same as for the healthy population
Step 4	Adjust fluid volume to meet requirements
Step 5	Calculate vitamin, mineral, trace-element, essential fatty acid (EFA) content of the final mixture, adjust or supplement as needed

Dietary recommendations:

Protein recommendations
For healthy individuals, protein recommendations are based on the rates of growth, protein deposition for children of different age groups, the amino acid composition of whole body protein, as well as the efficiency of dietary protein utilization and more recently by a stable isotopic technique.^1,2

In HT1 patients the majority of patients will take the TYR/PHE-free protein supplement, which will provide approximately 75% of total protein intake, the tolerance for natural protein for HT1 is comparable with Phenylketonuria³.

Amino acids do not require digestion and are directly available for absorption by the small intestine, which leads to rapid absorption and cause a transient imbalance of amino acids in the systemic circulation as opposed to whole protein intake^4,5,6

For HT1, the amino acid recommendations can be based on the natural protein recommendation with an added factor for the compensation of 20% for the use of amino acids instead of intact natural protein. Clinical practice differs throughout the world; no consensus exists on protein substitute dosage.

ESPKU preliminary recommendations for Protein in PKU, can also be applicable for TYR1:

Total protein intake should supply age-related safe levels of protein intake, based on WHO/FAO/UNU2007, with an additional 20% of L-aminoacids to compensate for the ‘digestible indispensable amino acid score’ and further 20% to optimize impact of L-AA on blood TYR control.

Protein recommendations for HT1, based on preliminary report of the ESPKU recommendations for protein in PKU:

Age	gProtein/kg bodyweight
0-2 months	2,5
2-12 months	2,0
1-4 years	1,5
4-10 years	1,2
10-14 years	1,1
>14 years	1,0

Energy requirements infants		Energy requirements children
Age/months	Kcal/kg/d	Age years	Kcal/kg/d – M	Kcal/kg/d – F
1	110	1-2	82	80
2	102	2-3	84	81
3	95	3-4	80	77
4	83	4-5	77	74
5	82	5-6	75	72
6	81	6-7	73	69
7	79	7-8	71	67
8	79	8-9	69	64
9	79	9-10	67	61
10	80	10-11	65	58
11	80	11-12	62	55
12	80	12-13	60	52
		13-14	58	49
		14-15	56	47
		15-16	53	45
		16-17	52	44
		17-18	50	44
		<18

Human energy requirements, report of a joint FAO/WHO/UNU Expert consultation. October 2001⁸

Fluid requirements, based on requirements of healthy population
Age	Weight (kg)	Recommendation (ml)
0-3 months		150 x weight (kg)
4-6 months		130 x weight (kg)
7-9 months		120 x weight (kg)
10-12 months		110 x weight (kg)
>1 year	1-10	100 x weight (kg)
	11-20	1000 + 50 x (weight in kg – 10)
	> 20	1000 + 20 x (weight in kg – 20)

Human fluid requirements Report of a Joint FAO/WHO/UNU expert consultation 2001⁸

% of Tyrosine found in protein of milk, cereals, vegetables and fruits⁹
Protein source	% Tyrosine found
Milk, cereals	5%
Vegetables	3% – 4%
Fruits	3%

References

Pillai RR, Kurpad AV Amino acid requirements in children and the elderly population. Br J Nutr, 2012, 108(Suppl 2) S44−9.
Lango R, Levesque C, Ball RO et al. Available versus digestible amino acids − new stable isotope methods. Br J Nutr, 2012, 108(Suppl 20) S306−14.
Hennermann JB, Roloff S, Gellermann J et al. Chronic kidney disease in adolescent and adult patients with phenylketonuria. J Inherit Metab Dis, 2013;36(5):747-756.
MacDonald A, Rocha JC, van Rijn M et al. Nutrition in phenylketonuria. Mol Genet Metab, 2011, 104(Suppl) S10−18.283.
Gropper SS, Acosta PB Effect of simultaneous ingestion of L-amino acids and whole protein on plasma amino acid and urea nitrogen concentrations in humans. J Parenter Enteral Nutr, 1991, 15 48−53.
Gropper SS, Smith JL Advanced Nutrition and Human Metabolism. California, USA: Wadsworth Cengage Learning, 2013, pp. 183−244.
van Rijn G, Carbasius Weber E. Dieet bij metabole ziekten 1st Ed. WKZ/UMCU Utrecht. 2011:24-38.
Human energy requirements, report of a joint FAO/WHO/UNU Expert consultation. October 2001
Dixon MD, MacDonald A, White F, Stafford J. In: Clinical Paediatric Dietetics. 4^th ed: West Sussex: John Wiley & Sons Limited, 2014:422.

Diet prescription - TYR I