Guide to Diet - Canadian Porphyria Foundation

Disclaimer
Care has been taken to ensure that the information in this guide is accurate at the time of production. This information is, however, intended for general guidance only. The Canadian Association for Porphyria disclaims for itself and for the author of this guide, all responsibility for any mis-statements or for consequences of actions taken by any person while acting on information contained herein. Physicians and patients must make their own decisions about therapy according to the individual circumstances of each case.

This guide is intended to give an overview of porphyria and some diet suggestions that may help minimize attacks or symptoms. It will address key points, such as: To develop a care plan that is specific to your condition, it is advised that you consult your physician and a dietitian.

What is Porphyria?

Please refer to the HEME PATHWAY for this section.

Porphyria refers to a group of rare conditions that are usually inherited, but may be acquired by way of chemical exposure or disease. There are different kinds of porphyria, but all are due to a deficiency of an enzyme involved in the production of "heme" (the red pigment or color of hemoglobin in blood).

Enzymes are protein substances produced by living cells, and are essential to life. They, in essence, get the necessary chemical reactions running in the body. Enzymes are also very specific, like a key for a lock.

Porphyrins, which are produced in the liver and bone marrow, are light-sensitive compounds, necessary for and involved in the production of heme. Heme is a mixture of iron and porphyrins, which goes on to make "hemoglobin". Hemoglobin is in red blood cells, and its job is to hold onto oxygen until the red blood cell reaches a destination where oxygen is needed. Hemoglobin also gives blood its red colour, and porphyrins give heme its colour. Additionally, porphyrins are involved in the production of myoglobin (the reddish muscle cell pigment) and cytochromes (found in all cells, also giving them colour). Since porphyrins ultimately give cells their red colour you can see why urine can sometimes be reddish coloured during a porphyric attack.

When porphyrins are produced faster than what the body can handle, they build up in the blood, urine and stool. This porphyrin excess is what gives one or many of these symptoms: stomach pain, light sensitivity, skin sensitivity, vomiting, overall muscle pain, and personality changes. In severe instances, breathing problems and seizures may result. This is why it's important to eat properly and regularly, and to avoid drugs or other things that may typically set off a porphyric attack.

Heme is produced via a variety of stages, which are called, "The Heme Pathway". This pathway is much like a recipe that needs many different ingredients added together, at different stages, to make the desired end-product.

Here is an analogy to explain this complex "pathway" in the body:
Imagine that the pathway is actually a river of porphyrins and porphyrin substances which together flow into and make up a big red-coloured pool called the Heme Pool. Like a recipe, various ingredients (or porphyrin substances) are added to this "river" at various stages to form the Heme Pool. Along this river there are several gates (which represent different stages of the Heme Pathway). These gates must be opened fully by an operator in order to keep the proper flow of the river into the Heme Pool. Each gate has a different operator that has a unique key (which we'll call an Enzyme Key) for the gate that he must open. The job of each operator is to insert their Enzyme Key into their gate, and to turn the key fully so that their gate will only open part way, thus decreasing the flow of the river, resulting in a lower level in the Heme Pool.

One day the operator at the third gate comes to work and is not feeling well. Because of past incidences, we know that when he wasn't well, he had taken medications that didn't agree with him; drank alcohol; didn't eat all day; or got too much sun. One or two of these things seemed to affect how he did his job.specifically how far he could turn the Enzyme Key in the gate. When he had exposure to these "irritants" before, it could not open fully. Regardless, he still has to go to work, since no one else can operate his gate. Unfortunately, because his gate doesn't open fully, the flow of porphyrins start the Pool to tell the first gate operator to turn up the porphyrin tap to increase flow. "Heme levels are decreasing!" they say, not even aware that the third gate operator isn't doing his job properly. This keeps continuing until there is a flood at the third gate. This flood puts the whole flow into chaos until the operator at the third gate can get back to normal. For this particular gatekeeper in the past, having him take sugar often helped him get back on track. In a worst case scenario, a specialist would have to be brought in to help get the third gate operator back to work and restore normal operations. If only he would have known to stay away from those irritants, he may not have had any problems!

In the different types of porphyria, different "gate operators" are affected by different irritants down the pathway. This is why there are different symptoms for different types. This story, although simplistic, helps visualize what is actually going on in the body when you have porphyric symptoms or an attack.