Nicole Merrifield

Born in the early 1980s, I was diagnosed with PKU, or Phenylketonuria (FEN-nil-KEE-toh-NOO-ree-ah), a genetically inherited disorder where the liver lacks an enzyme necessary for breaking down protein. The protein we eat is comprised of several amino acids and there is one amino acid in particular that my body cannot process: phenylalanine. Rather than convert phenylalanine (phe) into tyrosine, a building block known for helping to improve a person’s mood, the excess amino acid builds up and, overtime, can become harmful. Inherited by receiving two recessive genes, PKU is so rare that it only affects every 1 in 10,000 or 1 in 20,000 births, depending on where you look.

Fortunately, I was born during a time when newborn screening was mandatory and PKU was recognized as a condition that is treatable through the maintenance of a low-protein diet. For me, this meant not eating any meat, dairy products, NutraSweet or any other combination of foods that were known to be high in protein. Unfortunately, those who were diagnosed with PKU prior to any known treatment were oftentimes severely mentally handicapped.

As a child on the PKU diet, Phenyl-Free was the formula I was prescribed. I used to mix it with water using a mixer and drink it from a pyrex cup using a straw to avoid the bad taste.

As a child on the PKU diet, Phenyl-Free was the formula I was prescribed. I used to drink it straight from the same Pyrex measuring cup we mixed it in, but I had to have a straw to avoid the bad taste.

I grew up in a suburb not far from Pittsburgh, Pa., and maintained a low-protein diet for much of my early childhood. With PKU being (at the time) a relatively new science, my doctors had given me the assumption that one day I could throw away the gram scale, never conduct another blood test and above all else, eat anything I wanted. That’s because at a very young age, I was told I could discontinue the low-protein diet when I was 10. When my tenth birthday rolled around, the target age had been pushed to 16. And before I knew it, the new (and current) recommendation for PKU patients was to remain on the low-protein diet for life.

As many PKU patients often do when they reach the teenage years, I started to become more relaxed in following my diet. During one of my regular doctor appointments, my PKU geneticist (who I assume was frustrated with my lack of control on the diet) said, “You’re either on the diet, or you are off.” I looked at my mother, searching for some sort of guidance, when she told me, “It’s up to you.” It was then that I decided that I would go “off-diet.” The condition; however, was that if at any point my grades started to fall or if I had trouble concentrating, then I must return to the restricted diet.


Nicole Merrifield with husband Brandon, 2012

That was 19 years ago. While continuing to remain off-diet, I graduated high school, received my Bachelor of Arts cum laude, and recently completed my Master of Science degree while working full-time as a communications specialist for a U.S. Department of Energy contractor. My personal life has turned out well too. I am married to a fantastically supportive husband and have recently taken on the task of home ownership! It only seems natural that the next likely step in life is to start a family of my own. Yet, it’s the last of these personal goals that has forced me to revisit my PKU roots: women who are diagnosed with PKU must return to the diet and stabilize their protein levels prior to conception.

I realize that today’s young PKU patients have always been told they need to be on diet for life. My journey from a restricted to liberalized diet (and back again) is a rather unique story in the PKU community and could probably help other PKU patients considering the same options. That said, PKU Parlor is the platform upon which I will tell my story as I become re-familiarized with PKU, try out new recipes, investigate new medical advancements and most of all, learn to reintegrate PKU into my daily way of life.


Disclaimer: I am not a medical doctor and the comments I post on PKU Parlor should not replace the recommendations of your geneticist or PKU dietitian. PKU has as many variations of severity and you should always consult with your personal doctor before making any changes to your low-protein diet.

15 responses to “Nicole Merrifield

  1. James Kendall

    My wife has PKU and is currently suffering from schizophrenia like symptoms. I was doing research when I stumbled on your page here. After all the difficulties I have been reading about PKU, your site was a welcome change of pace. Thank you.

    • Nicole Merrifield

      Hi James, thank you for stopping by-even if it was by chance. I’m sorry to hear about the challenges facing you and your wife. Please feel free to visit often, post a comment or email me directly if you’d like: Best wishes, -NM

      • James Michael Feiling

        My name is Jim Feiling… I also have PKU and I wanted to thank you for sharing your story… It is an inspiration for me personally… to share mine, which I honestly have to say is interesting as well… thank you.

  2. My name is Neal Berthelot. I also have PKU. I am now 37 with three kids under 5 and am a stay at home dad. This Site is a great testament to those (like my self) who wish to pass on their life experience with PKU thus far… I started a blog as well and encourage younger tweens and teens to read my story as it is a great counter point to Nicole’s experience of going off the diet. Although back on my diet for 2 years and doing well, being off the diet for 20 years REALLY had a different effect on me. For those who wish to read more Great Job on the blog Nicole and good luck in the future with the family, There is nothing in the world better then raising a family!

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  4. This is really neat to read you blog. There is definitely a wide variety of attitudes and personalities in the PKU community, and I really like the educated and positive tone of your blog. : ) I thought it was cute that you drank your formula from a straw – I do that too!

    I am one who has never been off diet (and actually have never even considered it) so it’s been interesting to talk to people online who are trying to get back on. I have seen a lot of women struggle to get their levels back down after being off in order to get pregnant. So I think your blog will be really good for them!

    I am just curious, you obviously did well for yourself in the years you weren’t on diet. So were there any side affects for you? Did you have any mood or concentration problems?

    Best of luck!

    • Nicole Merrifield

      I never really felt like I had any side effects but I have heard others say they didn’t realize they were feeling crummy until they returned to diet. I’ve only been doing the diet for about a week now and for the most part I feel about the same with the exception that I am sleeping better than ever. I feel more restful when I wake than I have in a long time. Perhaps I’ll see more of an improvement the longer I stay on-diet.

      • Mackenzie


        you will feel so much better the more you watch your diet and the more careful you are. i have def slept alot better, better moods, better concentration, no head aches, just alot of way better things. i have been hard core for about 7 months and i wouldnt want it any other way. are you drinking formula? Cause i have noticed way more energy in myself since i have been hard core on my formula. i drink vitaflo orange powder packets and they arent bad at all. I use to hate my formula when i was little and i never drank it alot, so i was always hungry. Also since i was little they have raised my phe intake soooo much higher, which is awesome. I am still in the process of figuring out how high my phe intake is . when i was little i had only 17 exchanges in a day. now they have me at 800 mg of phe in a day. because my levels have been too low, they keep having to raise it. So we shall see where it leaves me when i take another level. So its not always a bad thing , you never know if you will be able to handle more. ya know. good luck 🙂

  5. Mackenzie

    my name is Mackenzie Guiliano (Marx is my maiden name). I live in dallas tx right now but i was born and raised in Pittsburgh pa also!!! 🙂 I randomly came upon your page when i was searching for PKU things. I am 26 years old and i was off diet when i was 9 years old because i was not growing right. When I got in my 20s i started feeling crummy and not myself. So I decided to slowly go back on diet when I was like 24 and then now at 26 years old i am fully on and drinking formula and Have been hard core about it for about 7 months now. i feel so much better on diet in so many ways. when i saw you are from pittsburgh i had to message you. what a small world and very ironic i came upon your page. who was your dietitian?? and Dr? Dr breck? Wendy sunquist? Nicole???

    this is so awesome!! Id love to keep in touch. All of my family is still in pittsburgh. so i go there often to visit. 🙂

    Id like to email back and forth– maybe facebook even. 🙂

    Mackenzie Guiliano

    • Cynthia Palamara

      hi Nicole and Mackenzie,
      my son is 21 and has PKU. we are from Pittsburgh, also. in fact, he just saw Dr Breck about a month ago. Wendy Sundquist moved to MD about 10 years ago and Nicole has left Children’s.
      congratulations to both of you on your return to diet. Jimmy, my son, is in a phase 3 clinical trial for peg-pal (about a year and a half so far). i, also, came across ‘pku parlor’ quite randomly. great blog, very inspiring. just had to respond when i saw the Pittsburgh connection…

      • Hi Cynthia! I love it when I get to chat with someone else from the ‘Burgh! Is Jimmy doing well on Peg-Pal? I’ve heard wonderful things about it but always want to know how hard it is to give yourself an injection. I imagine that the tradeoff of eating foods higher in protein is worth it! 🙂


        P.S. Thank you for the kind words about PKU Parlor!

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  7. Cynthia Palamara

    hi Nicole,
    Jimmy is doing great on peg-pal, thanks for asking ; ) his levels are in complete control and the injection process is just part of his day, much like brushing your teeth or getting dressed. at first, it must be done at the hospital/study center, but they eventually train you to do it yourself. he was/is very fortunate to be living in oakland (while attending Pitt) and that made it easier to show up on a daily basis. when needed, they would send a visiting nurse to give the injection (Christmas break, etc). now, he picks up his supply on a once a week basis. it is working out very well for him! enjoy the summer!

    • Jason

      Hi Cynthia,
      My son is 11 and has PKU and while he will drink his formula, he’s still hungry and is not a big fan of fruits and vegetables. So it is getting more difficult to keep his hunger in check. Did your son try Kuvan before he started the PEG PAL, if so, did he respond? Do you know how long the Phase 3 trials for PEG PAL are supposed go?
      Thanks Jason

  8. Lucy Lee

    Hi, Nicole, I am a Older PKU Adult. I was born before mandatory testing. I will be 60 years old this July. I am not looking forward to it. I am not sure if I have anything in common with you other than PKU. I come from a family of 8 children. 4 of us have PKU. Two of us 4 are Mentally Retarded and have been in State homes their entire life. Myself and my younger have Classic PKU. I am currently on diet. My brother has been off his diet since he was 3 years old and does not seem to have any problems. The reason I am on diet is when I was young the Dr.s made a math error on my diet. I did not know the diet was for life until years after my daughter was born. I was not on diet when I became pregnant. I was at a PKU workshop in Austin Tx in 1985. There were teenager still on their diet. I was at one time the only PKU mother in the state of Texas. I have a long PKU history. I hope your PKU wish list comes true. PKU has come a long way, but still needs things to be done for PKU. Anyway Thanks for listening. Lucy Lee

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