Different people with PKU have different tolerances for phenylalanine. These responses are according to my personal experience with PKU and my tolerance as an adult with well-managed PKU.
What is PKU?
PKU is a genetic metabolic disorder. I cannot digest protein properly. There is one amino acid –phenylalanine, that my body doesn’t metabolize efficiently. Because of this I have to eat a low-protein diet in order to avoid a build up of phenylalanine in my blood that would cause neurological damage.
Do you have classic PKU?
No, I have a milder case. There are different mutations and I have not been analyzed to find out which one I have. My Phe allowance growing up was 400 – 600 mg Phe per day. That is about 8-10 g of protein. When I am pregnant (toward the end) or nursing I can tolerate more protein.
What can you NOT eat?
Meat, nuts, milk*, cheese, eggs*, tofu, soy products, normal pasta, whole wheat bread, nutrasweet, jell-o
*Because PKU is not an allergy, if there is a small quantity of milk or eggs in a food, I can sometimes eat it, depending on the amount of protein.
So…what DO you eat?
Rice, vegetables, fruit, rice or corn cereals, non-dairy ‘milks’, white bread, potatoes, chips, and special low-protein pastas made from starch, sorbet
If you can’t eat protein, how do you stay alive?
I drink a special formula every day that has all the amino acids and vitamins and minerals I need, minus phenylalanine. The amount I drink also gives me about 1000 calories. So this is a huge supplement in my diet both nutritionally and calorically. This way I am perfectly nourished, despite my restrictive diet.
What would happen if you ate too much protein?
This would cause high levels of phenylalanine in my blood and potential brain damage. There is not an allergic reaction or even an immediate effect. At this point in my life (when my brain is almost fully developed) it would probably cause cognitive and emotional problems – a lack of clarity, concentration issues, anxiety, depression. But I’ve never tried it. If a child with PKU does not eat a low-protein diet they may develop mental retardation.
What are some of your favorite foods to eat?
Toasted tomato sandwich, avocado sushi rolls, fruit smoothies (no dairy), low-protein taco salad/burritos.
What do you do when you go to restaurants?/Can you eat out?
I do eat out occasionally. I have come to love Asian restaurants. It’s pretty easy to get a vegetarian dish. At Mexican restaurants I usually order a tortilla with rice, tomatoes, lettuce and maybe guacamole. Even if it’s not on the menu, I’ve never had a problem ordering that. As a child I remember my family bringing my low protein pasta to restaurants for them to warm up. I would also eat salad (no cheese) and french fries.
How did you find out you had PKU?
Every baby in the U.S. and many developed countries is tested at birth as part of newborn screening. PKU was actually the first disorder to be tested by that heal prick, but now the test screens for dozens of diseases. The PKU test was first done on a large scale beginning in 1963.
Is PKU genetic? Does anyone else in your family have it?
PKU is a recessive gene mutation. My parents are both carriers. I have two sisters, and no one else in my family has it. Neither of my daughters have PKU but they are carriers. We do not know if my husband is a carrier, but it’s unlikely (about 1 in 50 chance). If he were, each of our children would have a 50/50 chance of being PKU positive.
How does PKU effect your pregnancies?
As a woman with PKU, it is extremely important to have blood levels in the safe range well before and during pregnancy. My blood Phenylalanine crosses over to the baby via the placenta at a concentrated level and affects fetal development. If my levels were high there would be a risk of birth defects. I have always kept my blood levels in this safe range, so I didn’t need to change anything in preparation for pregnancy. During pregnancy I am monitored by my doctors. I have one appointment per trimester, but send in blood samples (from a finger prick) every week to make sure my levels are good. Sometime during the second trimester I am usually allowed even more protein than normal in my diet, because the growing baby is absorbing a lot of it for growth.