PKU and Your Diet

Diet for life

A big challenge in life with PKU is the Phe-restricted diet. When you go to a restaurant and all you can get is a salad—“but no, not the bleu cheese; oh I can’t have ranch either…what’s in the house? You know, just give it to me plain”—you may feel limited, not just in dietary options, but in social settings as well. But there is enough scientific evidence to suggest that “diet for life” is important.

What do the experts say about diet for life and the goal for blood Phe levels?

In 2000, a National Institutes of Health (NIH) panel of experts decided that lifelong care is required for the treatment of PKU.¹² This solid statement settled the debate about how long people with PKU should remain on the diet. This was the statement that has come to be known as “diet for life.”

There was a time when people believed that it was only important to stay on the diet until about age 6 or 8, when the brain is growing the most. Even though it is still not fully understood why high Phe levels can cause brain damage, more evidence is suggesting that maintaining relatively low Phe levels is important in adulthood as well as childhood.

What should we aim for?

Just as it is important to keep the PKU “diet for life,” the NIH experts also agree that there is a certain goal for Phe levels in people with PKU. The experts said, “Maintenance of Phe levels between 2 and 6 mg per dL for newborns through 12 years of age appears to be medically necessary for ensuring optimal outcome.”¹² The range that they suggest (2–6 mg/dL) is a common target that people with PKU should aim for. Because we are all different and our bodies may have different needs, the experts left a little “wiggle room” for doctors and dietitians to determine individuals’ Phe tolerance.

The important thing to remember is that people with PKU should stay on the diet for life and aim to keep their blood Phe in the target range provided to them by their doctor or dietitian.

What will enable me to attain my target Phe goal?

A combination of these items has been the basis for PKU management for years:

• Phe-free formula
• Phe-free protein replacement bars
• Low-Phe natural foods
• Low-Phe medical foods

In the future, there may also be pharmaceutical therapy that would reduce blood Phe and potentially allow a person with PKU to eat more foods from a normal diet while keeping blood Phe levels low. New research continues in this area.