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3rd Dietitians’ Workshop

3rd Dietitians’ Workshop
  • Endocrinology and metabolism
  • Phenylketonuria (PKU)

Resource type



Dietitians, nutritionists, psychologists and physicians from across the world met in Istanbul (Turkey) on March 14th 2013 to discuss the latest research and developments in the dietary management of PKU.

Over 100 delegates heard presentations detailing the latest research in PKU management. Opportunities to discuss issues raised by the main presentations, compare and contrast local practices and share best practice were provided by workshop sessions. Themes explored included:

  • evaluating the challenges of the nutritional management of PKU, in particular the occurrence of obesity and bone mineral density
  • consideration of new perspectives in the dietary management of PKU, including nutritional support for adult patients and the development of taste and taste preferences
  • development of dietetic guidelines for PKU with an appraisal of the differences in PKU dietary management among Europe, USA and the rest of the world.

dietitians welcome

Prof Anita MacDonald1 , introducing the workshop, noted that over half of the delegates were medics. It was, she said, a reflection of the differences between countries in the delivery of nutritional support to patients with PKU.

The final program, abstracts, a selection of presentations and videos recorded during the Workshop are available on the Serono Symposia International (SSIF) website.


Challenges of nutritional management

Obesity, a global epidemic


Childhood obesity is a concern, said Dr Júlio Rocha2 , because of not only the high prevalence but also the lifelong health effects, such as cardio metabolic diseases. But is obesity a particular concern with PKU?

Measuring obesity is not easy, a range of methods are available but interpreting results can be problematic. Body mass index (BMI) scores can be a useful indirect indicator of body fat but more direct methods, such as dual energy X-ray absorptiometry (DXA), bioelectrical impedance analysis (BIA) and plethysmography give more accurate evaluation of abdominal/visceral fat tissue.

Dr Rocha reflected that key information to assess the overall ‘health’ of the PKU diet is lacking. There is also a lack of knowledge about the impact of food supplements. The stated carbohydrate levels of supplements may not appear high compared to natural foods, but in what form are these carbohydrates? How much is sugar?

Obesity in PKU

obesity in pku

There are no evidence-based studies clarifying if overweight in PKU can be related with the disease itself or with the special diet together with lifestyle behavior, said Prof Hulya Gokmen-Ozel3  in her following presentation

Generally, in PKU, high energy foods are encouraged because of the importance of dietary energy intake in maintaining good Phe control and the influence of energy on protein utilization and nitrogen balance. Such foods promote anabolism and prevent protein insufficiency.

Prof Gokmen-Ozel discussed the results of a European Nutritional Expert Panel in PKU (ENEP) study that had looked at the prevalence and dietary practice in obesity at PKU centers within 10 European countries. The study found that the definition of obesity varied from country to country and a range of measurements were used to define obesity.

Accepting that the variations in the methodology make data comparison difficult, Prof Gokmen-Ozel presented preliminary results which showed:

  • 15-34% children below 18 years were defined as overweight or obese
  • 23-52% of adults were overweight or obese
  • females are more prone to obesity in early ages, but males later in life
  • PKU patients are not more likely to be overweight or obese than the general population.

Bone status in PKU

bone fracture

There are a number of studies that show bone mineral density (BMD) is reduced in PKU, said Dr Martijn de Groot4 . Reported mean BMD values typically range from 0.5 to 1.00 standard deviations (SD) below the mean of matched controls. Reduced BMD could increase fracture risk at different ages, particularly later in adult life, as adequate bone mineral accrual is essential to prevent the development of osteoporosis and associated fractures.

The cause of reduced BMD in PKU is unknown. Elevated    blood-phenylalanine (Phe) concentrations, increased variations of blood-Phe concentrations, insufficient nutritional value of dietary therapy and noncompliance to therapy have been suggested as potential causes. Pathophysiologically, reduced BMD in PKU could result from decreased bone synthesis and/or increased bone degradation. Recent findings suggest that the latter is at least partly involved.

Whether there is a resultant increase in the risk of fracture with ageing is not yet known, but Dr de Groot recommended that monitoring with DXA and recording the levels of key biochemical markers, should be considered.

There is no clear treatment for BMD in PKU at this time. Promoting weight-bearing exercise is worth considering as a treatment advice. Prescribing calcium and vitamin D supplements is only of value where there are deficiencies. There is no evidence that bisphosphonates have any indication.


New perspectives in dietary management

A matter of taste

matter of taste

Taste preferences are developed early in life, from before birth until six months, explained Prof Kees de Graaf5 . Various factors can play a role in this, such as cultural, health-related and social behaviors. Children develop preferences for foods that have an ‘energy reward’, such as sugars and fats.

It is possible to influence children to develop a taste for ‘unpleasant’ foods such as protein hydrolysates if they are exposed to them in the ‘window’ of the first six months of life.

The taste preferences of children up to 3-4 years of age can be modified through repeated exposure to certain foods over a short period. However this gets harder as the child gets older.

Managing adults

managing adults

It is important to find ways of engaging with adult patients and to keep listening to how the patients themselves prefer to be managed, said Ms Sarah Boocock6 .

Patients, whether on or off diet, need support that works. This is particularly a challenge when patients have moved to an adult hospital where they are expected to take care of their own management.

Methods used with adults by the University Hospitals Birmingham (UK) include:

  • sending reminders via email, text messages and social media
  • providing psychological support (especially for pregnant women)
  • making access to hospital services easier.


Initial results suggest that this kind of support improves adherence.

Oral presentations

oral presentations 1

News of the success of ‘le Phetout’, an education tool for PKU patients was presented by Ms Annie Spiewak7. The tool helps PKU patients to calculate the Phe content of different foods. Following initial trials with over 100 patients, a new version of the tool with wider food options is being developed.

oral presentations 2

Do PKU patients have adequate physical development? This is, said Dr Amaya Bélanger-Quintana8  a controversial issue. The published studies provide data for only a few countries and primarily address the first years of life. Also, many of the existing studies are old and do not reflect new dietary management options. Dr Bélanger-Quintana introduced an ongoing retrospective multicenter multinational study in Europe that was comparing the developmental and dietary data from birth to 18 years of age in PKU patients. To date, preliminary data show that 57% of children seem to grow as expected, 23% grow less than expected and 20% grow more than expected.

oral presentations 3

Preventing maternal PKU syndrome in a second or third pregnancy requires high levels of support as it places a huge practical and social burden on the patient and their family said Dr Margreet van Rijn9 , presenting the case of a young pregnant PKU woman in her second pregnancy.


1 - Prof Anita MacDonald (Dietetic Department, The Children’s Hospital, Birmingham, UK)

2 - Dr Júlio César Rocha (Centro de Genética Médica Dr Jacinto Magalhāes, Porto, Portugal)

3 - Prof Hulya Gokmen-Ozel (Department of Nutrition and Dietetics, Hacettepe University, Ankara, Turkey)

4 - Dr Martijn J. de Groot (Beatrix Children's Hospital, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands)

5 - Prof Kees de Graaf (Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands)

6 - Ms Sarah Boocock (University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK)

7 - Ms Annie Spiewak (CHU Pellegrin, Bordeaux, France)

8 - Dr Amaya Bélanger-Quintana (Unidad de Enfermedades Metabólicas, Servicio de Pediatría, Hospital Ramón y Cajal, Madrid, Spain)

9 - Dr Margreet van Rijn (Section of Metabolic Diseases, Beatrix Children’s Hospital, University Medical Center Groningen, Groningen, The Netherlands)

Terms of use

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İstanbul, Turkey
Mar 14, 2013
Target audience
Dietitians, nutritionists, Healthcare professionals
by Excemed
Endocrinology and metabolism