Karen Harris
Rita - Here's some info for you: A proper diet is important to all individuals, regardless of health. Everyone should maintain a diet that provides all essential nutrients and should avoid being overweight or underweight. A desirable weight should be maintained by good dietary habits over a long period of time rather than be alternating periods of overeating and under eating. Diet is important in the management of many diseases, diabetes mellitus for example. Also, many diseases can alter food intake. Therefore, attention to diet and nutrition is important in almost any disease. Importance of nutrition in porphyria Porphyrias are due to deficiencies in enzymes in the chemical pathway that makes heme from porphyrins and other precursor substances. This pathway of enzymes is called the heme biosynthetic pathway. Enzyme deficiencies in the porphyrias are usually inherited. However, the enzyme deficiencies along do not produce disease. Additional factors determine whether or not there will be disease manifestations. Diet is one of the additional factors that influences the manifestations of certain types of porphyria. The so-called acute porphyrias, which are acute intermittent porphyria, hereditary coproporphyria and variegate porphyria are characterized by acute attacks of abdominal pain and other symptoms. Attacks of these diseases can be brought on by restricting intakes of carbohydrate and energy. (Energy is measured in calories or kilocalories.) Conversely, providing a normal or increased intake of carbohydrate and energy is part of the prevention and treatment of attacks of porphyria. Therefore, attention to diet is particularly important in these three diseases. The acute porphyrias are affected by diet because the chemical pathway in the liver that makes heme from porphyrins and other precursor substances is very sensitive to intakes of carbohydrate and energy. In the acute porphyrias porphyrin precursors (8- aminolevulinic acid and porphobilinogen) and porphyrins are produced in excess amounts by the liver. Porphyrin precusors are in excess especially during acute attacks of porphyria. Nutritional Recommendations for the Acute Porphyrias The following are general recommendations that may not apply to all patients with acute porphyria. Individual nutritional needs vary and are affected by the nature and severity of a disease. Therefore, a physician should be consulted and the advice of a dietitian sought before implementing dietary recommendations for a complex medical condition such as porphyria. Other recommendations may need to be added or substituted to meet the needs of an individual patient. These general nutritional recommendations for acute porphyrias are very similar to those for diabetes meilitus. Therefore, physicians and dietitians may find that dietary instructions given for a patient with acute porphyria are not very different from that given for a disease they encounter much more frequently than porphyria. Nutritional recommendations for acute intermittent porphyria, hereditary coproporphyria and variegate porphyria emphasize a high carbohydrate intake as part of a balanced diet that provides all essential nutrients. The recommendations include an adequate intake of dietary fiber, vitamins and minerals. The goals are to prevent acute attacks of porphyria that may be related to diet, avoid deficiencies of nutrients and maintain a normal body weight. The following dietary guidelines are recommended. Energy intake should be prescribed at a level to maintain a desirable body weight. Carbohydrate intake should be 55 to 60 percent of total energy intake. Protein intake should follow the RDA. (Recommended daily allowance.) This may be increased in elderly subjects, and reduced if there is kidney impairment. Total fat intake should be less than 30 percent of total calories. (Particularly in individuals with high blood cholesterol levels, saturated fat should be less than 10 percent of total energy intake, polyunsaturated fat 6 to 8 percent, and the remainder monounsaturated fat.) Cholesterol intake should be less than 300 milligrams per day. Artificial sweeteners are acceptable. Salt intake need not be restricted unless it is important for controlling hypertension. (The management of hypertension (high blood pressure) may include salt restriction. This is not discussed here because most patients with porphyria do not have persistent hypertension.) Intakes of vitamins and minerals should meet the RDAs. Calcium intake in women should be at least one gram daily. Iron intake should be adequate to avoid iron deficiency. Women with heavy menstrual blood loss and patients who have had frequent blood drawings due to illness and hospitalization may require greater intakes of iron. (Iron is a component of heme. Iron deficiency can compromise heme synthesis and may exacerbate porphyria. Therefore, iron deficiency should be avoided in porphyria. Early iron deficiency occurs before there is anemia (low blood count). Early iron deficiency can be detected by tests such as serum iron and iron-binding capacity, and serum territin.) Alcoholic beverages should be avoided. Alcohol stimulates the heme biosynthetic pathway in the liver and can itself exacerbate porphyria. Alcohol has other harmful effects and can lead to weight gain. Some experts feel that small amounts of alcohol are not harmful in porphyria while others feel that even small amounts should be avoided. fiber intake should be about 40 grams per day, but should not be increased above 50 grams per day. (A high-fiber diet may increase the requirements for calcium, iron and trace minerals. High dietary fiber intakes should be avoided in patients with upper gastrointestinal problems (abnormalities in the esophagus or stomach) because sometimes excess fiber can accumulate in the form of "bezoars." Increasing dietary fiber intake sometimes causes abdominal cramping, diarrhea and flatulence. These can be minimized by increasing fiber intake gradually.) Foods contain many natural chemicals that can stimulate the heme biosynthetic pathway. Although none have been definitely linked to attacks of porphyria, the possibility that these chemicals might contribute should be kept in mind especially when attacks of porphyria recur in the absence of a definite inciting factor. Some of the dietary factors that might have an adverse effect on porphyria include charcoal-broiled meats (which contain chemicals similar to those found in cigarette smoke), certain vegetables (such as cabbage and brussel sprouts which may contain chemicals that in large amounts can stimulate heme and porphyrin synthesis), and high intakes of protein. Probably, none of these foods need to be completely avoided in porphyria. However, it is important to consume a well-balanced diet and not to consume any particular type of food in excess. (The best way to maintain a well-balanced diet is to learn to eat a variety of foods from what are commonly referred to as the four major food groups. Detailed advice on how to do this should be sought from a dietitian.) Devising a Diet for the Individual Patient Dietary recommendations such as those listed above need to be translated into a diet plan for an individual. This is best done with the advice of a physician and the help of a dietitian. It is standard practice for a physician to prescribe a diet for an individual, and for a dietitian to assist the patient in devising an individualized meal plan. The following are some considerations in devising a dietary plan to achieve the goals of a dietary prescription. Food intake should be consistent, but should take into account lifestyle and physical activity. The total daily energy intake should be distributed consistently with at least three regular meals each day. Total energy intake must be individualized, because it varies with age, sex, and body weight, and is affected by physical activity. (Dietitians employ standard methods to estimate daily energy requirements. One of these methods is the Harris-Benedict equation.) It can also be greatly altered by illness. Weight reduction in patients with acute porphyria Being overweight is a particular problem in patients with one of the acute porphyrias because reducing the intakes of carbohydrate and energy in an effort to lose weight can worsen these diseases. Severe acute attacks have occurred in patients who attempted to lose weight rapidly with very low energy diets. Patients with acute porphyria should avoid very low energy diets, and should inform their physician or nutritionist that they have one of these diseases before they enter a weight-loss program. Also they should not participate in a weight loss program except under the supervision of a physician. Patients with acute porphyria who are overweight and wish to lose weight should be prescribed a diet that will result in gradual weight loss. The energy intake should be 500 to 1000 kilocalories (or not more than 10 percent) below that needed to maintain weight. The diet should be well balanced and nutritionally complete. It may require time and considerable discipline to adjust ones diet to a moderately reduced level of energy intake. The patient will need to learn more about foods and the nutritional contents of foods in order to be successful in losing weight with this type of regimen. In contrast, entering a "crash diet" program requires little knowledge of nutrition in order to achieve a short term loss of weight. It may seem that overweight patients with porphyria are at a distinct disadvantage, because it is unsafe for them to enter into programs that can lead to rapid loss of weight. It should be remembered, however that most overweight individuals who lose weight rapidly eventually regain the lost weight. A regimen of moderate energy restriction, such as that recommended here, is in fact the medically preferred method of weight loss for all individuals. A patient who achieves the discipline and knowledge about diet that is required to lose weight in this manner is likely to enjoy more favorable long term results. In addition to avoiding attacks of porphyria, other medical complications of very low energy diets (gallstones, for example) do not occur with a regimen of moderate energy restriction. Nutritional management of acute attacks of porphyria Intravenous administration of glucose (a pure form of carbohydrate) is part of the standard treatment of acute attacks of porphyria. Glucose is given by vein because the stomach and intestine usually do not function properly during an attack, and material taken by mouth is not properly propelled through these organs. Glucose and other carbohydrates can repress the pathway for synthesis of herne in the liver. As a result, the overproduction of prophyrin precursors and porphyrins is repressed by carbohydrate administration. Heme therapy (intravenous administration of hematin or heme arginate) has a similar but much more potent effect, and probably leads to more rapid improvement. Therefore, heme rather than glucose is becoming more accepted as initial therapy for an acute attack. However, it is still important to administer glucose and other nutrients. Particularly if an acute attack is severe or prolonged, sufficient glucose can be given by vein to meet the total energy requirements of a patient. This is best accomplished by a catheter that is inserted into a large central vein. Additional nutrients, including vitamins, minerals, amino acids and fat can be given in the required amounts to maintain all requirements. Provision of total nutritional needs in this manner by vein is commonly called "total parenteral nutrition". Oral feedings can be introduced gradually as recovery from an attack begins to occur and there are signs that functions of the stomach and intestines are improving. After recovery from an attack a high carbohydrate regimen should be prescribed, as described above. Additive effects of other factors Nutritional changes are being increasingly recognized as factors that can bring about acute attacks of porphyria. However, harmful drugs (such as barbiturates and sulfonamide antibiotics) and steroid hormones (especially progesterone) are also important. Some women develop attacks during the second half of the menstrual cycle, when progesterone levels are high. Often an attack is due to a combination of factors rather than a single one. For example, attacks in women are more likely to occur due to a dietary indiscretion when progesterone levels are high than at other times. A dietary indiscretion also increases the chances that a harmful drug or alcohol will produce an attack. Consideration of the additive effects of many inciting factors has important implications for management of acute porphyrias. For example, attention should be given to diet and nutrition even in a patient with attacks that seem to be due primarily to a drug or a hormonal fluctuation. Eating behavior and porphyria Sometimes patients with acute porphyria have symptoms such as profound weight loss, recurrent vomiting, and eating attitudes that suggest "eating disorders" such as anorexia nervosa or bulimia. Usually these symptoms are due to porphyria itself and do not represent a primary eating disorder. However, mild forms of eating disorders are common, especially in young women, and difficult to recognize. Mild forms of eating disorders may have few consequences in healthy individuals. However, the effects can be profound when combined with a medical condition that is sensitive to changes in diet. For this reason, the study of eating behaviors has come important in a number of diseases such as diabetes, cystic fibrosis and inflammatory diseases of the intestine. There have been few studies so far in porphyria. Eating behavior is assessed not only by determining the dietary intake of a subject, but also by assessing eating attitudes and habits. This is done with questionnaires that are different from those used to assess dietary intake alone. It is likely that these assessments will become increasingly useful for the management of porphyria in the future. For the present, physicians familiar with eating disorders and dietitians may be most likely to recognize abnormal eating attitudes and behaviors that may contribute to attacks of porphyria. Nutrition in other types of porphyria A balanced diet that provides all essential nutrients is important for everyone. Otherwise, only a few specific dietary recommendations are justified for types of porphyria other than the acute porphyrias. ALAD porphyria (porphyria due to a deficiency of 8-aminolevulinic acid dehydratase). Effects of diet on this extremely rare condition have not been reported. However, because it bears some resemblances to the acute porphyrias, at least some of the same nutritional considerations may apply. Congenital erythropoiatic porphyria. Diet does not appear to play a specific role in this condition. The excess porphyrins in this condition originate from the bone marrow. The heme biosynthetic pathway in the bone marrow seems to be much less sensitive than in the liver to changes in carbohydrate and energy intakes. Because patients with this condition may be severely ill, however, their diets may be inadequate. Such nutritional deficiencies should be prevented because they may contribute to anemia and other manifestations. Porphyria cutanea tarda. Even though porphyrins in this condition originate from the liver, carbohydrate and energy intakes have not been described as major determinants of disease activity. However, excess iron and alcohol are clearly important. Alcohol and iron supplements should be avoided. Restriction of dietary iron is usually not necessary. Erythropolietic protoporphyria. Excess protoporphyrin in this condition originates primarily from the bone marrow, which as noted above is not highly sensitive to changes in energy and carbohydrate intakes. The bone marrow is sensitive to iron deficiency which, therefore, should be prevented by assuring an adequate intake of iron. Iron supplements should probably not be given unless laboratory tests for iron suggest that stores of this mineral are low. Occasionally, the liver seems to contribute significantly to excess protoporphyrin production in erythropoietic protoporphyria and there can be significant liver damage. For this reason, patients with this condition may be advised to follow dietary recommendations similar to those for patients with the acute forms of porphyria. Some basic information on diet and food choices Most people have little knowledge about the nutrient content of foods and the normal requirements for specific nutrients. What follows is some general information on these matters. This is not intended to replace information and advice on individual nutritional needs, which are best provided by a physician or dietitian. Included below are some of the standard dietary guidelines for healthy people. It should be evident that these do not differ very much from the dietary guidelines given above for patients with porphyria. People chose foods - not nutrients - when shopping, preparing meals at home, or ordering meals in restaurants. Their choices are determined by factors, such as ethnic background, culture, tradition, habits developed during childhood, income, education, occupation, marital status and age. Advertising of food products and recommendations by government agencies, health organizations, and health care providers also play an important role. Seasonal and regional availability and cost also influence choices. Agricultural policies, food regulations, and programs for feeding the poor are also important. Diet Composition Foods are composed of varying amounts of the following. The major macronutrients (fat, protein and carbohydrate) Minerals that are readily available because they are found in man large amounts (sodium, potassium and chloride). Minerals needed in large amounts and found mostly in particular foods (calcium, phosphorous and magnesium). Vitamins needed in known amounts. Trace minerals needed in small, known amounts (iron, zinc, iodine, fluorine). Trace minerals needed in small but less defined or unknown amounts (chromium, manganese, copper, selenium, molybdenum). Minerals of unknown value at least in humans (nickel, tin, vanadium, silicon, arsenic). Water. Non-nutrient substances. Non-nutrient substances include dietary fibers, which may impair the absorption of some nutrients, but improve colonic function and are possibly protective for cancer and arteriosclerosis. Other non-nutrient substances include phytate, oxalate and other chemicals that can bind calcium, iron, zinc and other minerals and reduce their absorption. The nutrient compositions of various foods have been determined by chemical analysis and other methods. These have been compiled, most notably by the U.S. Department of Agriculture. These compositions are approximate, and may vary considerably. The "normal American diet" is highly variable among individuals and can also vary considerably in a given individual over time. Most Americans consume approximately 10-15 percent of total energy in the form of protein, 40-70 percent as carbohydrate, and 30-60 percent as fat. Nutritional Requirements The Recommended Daily Allowances (RDA 's) provide a means of assessing the adequacy of intakes of nutrients. RDA's are the levels of intake of essential nutrients considered to meet the known nutrition needs of practically all healthy persons. (RDA's are established on the basis of available scientific knowledge by the Food and Nutrition Board of the National Academy of Sciences.) An RDA is not as average requirement but rather is considerably above the average requirement. (In statistical terms, an RDA is roughly two standard deviations above the estimated average requirement for healthy people.) As a result, only a very few healthy people may require more than the RDA and most people will actually require less than the RDA. RDA's vary with age and sex, and are tabulated as such. There are no RDA's for calories, carbohydrate or total fat. RDA's are for healthy individuals. Nutrient requirements may be altered by disease. The U.S. RDA for a nutrient is somewhat different. It is the legal standard established by the Food and Drug Administration and is used on many food labels. Its aim is to inform shoppers about nutritive values of foods. It is based on the RDA but is modified to provide a single value for the entire population in the U.S. four years of age or older. For most nutrients the U.S. RDA is the same or larger than the RDA.