|
PORPHYRIA FACTS - NUTRITION -
PORPHYRIA DIETARY LIST
Avoid
Alcoholic beverages
Negative caloric intake < BMR calories daily
Low carbohydrate intake < 300 grams daily
* During active AIP < 450-500 grams daily including iv infusion supplementation.
Fasting > 3 hours
*Vital to have steady carbohydrate intak around the clock.
P-450 foods
grapefruit juice listed as a P450 inhibitor.
Caffeine is a P-450INhitor (greatkly uses P-450.
Porphyrinogenic foods
* Porphyrinogenic foods contain chemicals that stimulate heme synthesis.
Cabbage
Brussel sprouts
Red plums
Red grapes
Red/purple grape juice
Sulphur containing foods
Tomatoes
Cabbage
Cauliflower
Broccoli
Brussel sprouts
Kale
Kohlrabi
Mustard
Rutabaga
Turnips
Egg Yokes
Sulphite containing foods
*Be aware of preservatives in foods as most contain sulphhites.
Dried fruit
Lemon & Lime juice
WIne
Molasses
Sauerkraut
Fresh shrimp
Grape juice
++++++++++++++++++++
Sulphites
Sulphur dioxide and other sulphites are inexpensive preservatives, very
effective, and widely used. They are both antioxidants which prevent browning
of fresh fruits, and preservatives with a broad spectrum antimicrobial action as
used in soft-drinks, wine and maize milling.
Sulphite preservatives
Sulphur dioxide
Sodium bisulphite
Sodium metabisulphite
Sodium sulphite
Potassium bisulphite
Potassium metabisulphite
Incidence
Sulphites appear to affect mainly asthmatics, and children more than
adults.
Approximately 10% of American adult asthmatics are sensitive to sulphites.
Forty three percent of children with asthma attending the Allergy Clinic at Red
Cross Hospital reacted to a sulphite challenge with a fall in forced expiratory
volume in 1 second (FEV1) of 10% or more and 21% with a fall in FEV1 of more
than 20%.
Significantly, many of these patients were asymptomatic.
The sulphite challenge dose was approximately equivalent to that used in 250
mls of a common sulphite containing soft-drink.
Of interest is that more girls were affected (64.3%) than boys (30.4%).
No prevalence studies have been done on normal subjects, but of all severe
sulphite reactions reported to the FDA approximately 30% occurred in
non-asthmatics.
Sulfites
Products That Contain Sulfites
Sulfites can occur naturally in foods or are added to enhance food products.
Sulfites are made naturally during the fermentation of wine.
There is a variety of foods that contain sulfites.
Some of them include baked goods, soup mixes, jams, canned
vegetables, pickled foods, gravies, dried fruit, potato chips, trail mix, beer, wine,
vegetable juices, bottled lemon juice, bottled lime juice, tea, condiments,
molasses, fresh or frozen shrimp, guacamole, maraschino cherries, and
dehydrated, pre-cut, or peeled potatoes.
Foods that may contain sulfites (partial list)
Alcoholic Beverages (labeling of sulfites in alcoholic beverages is required if the
concentration is 10 parts per million or greater)
Bakery Items: Breads containing dough conditioners, cookies, crackers, pie and
pizza
crusts, tortillas, waffles
Beverages: Beverages containing sugar or corn syrup, dried citrus fruit
beverages, canned
bottled, and frozen fruit juices.
Condiments: Horseradish, relishes, pickles, olives, wine vinegar.
Dairy: Processed cheese foods.
Dried Foods: Dried herbs and spices, dried fruits, trail mixes.
Fish and Shellfish: Fresh shrimp and scallops frozen, canned or dried clams,
shrimp,
lobster, crab, scallops, dried cod.
Fruits: Fresh grapes, dried fruits (including raisins and prunes and especially
pale fruits that
have not discolored), canned, bottled and frozen fruit and juices, maraschino
cherries, glazed
fruit.
Gelatins, Fillings, Frostings: Fruit fillings, flavored and unflavored gelatin, pectin,
jelling
agents, canned frostings and frosting mixes.
Grain Products: Cornstarch, modified food starch, spinach pasta, gravies,
hominy, breading,
batters, noodle and rice mixes.
Hard Candies
Jams and Jellies
Nuts: Shredded coconut.
Plant Protein Products: Soy protein products including tofu, textured vegetable
protein,
infant formula.
Snack Foods: Filled crackers, dried fruit snacks, trail mixes, tortilla chips, potato
chips.
Sugars: Brown, white, powdered and raw sugars.
Vegetables: Vegetable juices, canned vegetables (including potatoes), pickled
vegetables
(including cauliflower, peppers, sauerkraut), "fresh cut" potatoes (as delivered to
restaurants),
frozen vegetables (including french fries and deli potato salad).
Iron supplements
Restrict fat and proteins during active AIP, otherwise follow RDA.
*Remember that AIP increases CSF protein levels, elevates cholesterol, lipids
and glucose intolerance.
High fiber intake due to bezoar formation in AIP patients. < 40%
Chamomile containing foods
* Known sensitive reaction in AIP patients, like that of ragweed.
Possible sources of sulphites in foodstuffs
Beverages
Soft-drinks, fruit juices, grape juice (esp
citrus drinks)
Alcoholic Beverages
Wine, beer, cocktail mixes
Condiments
Wine vinegar, pickles, salad dressings
Confections
Molasses
Dips
Avocado and others
Fish
Canned or fresh shrimps, shellfish
Fresh fruit, vegetables
Grapes, fresh pre-cut potatoes
Gravies
Gravies, sauces
Processed fruits
Dried fruit, fruit juice concentrates,
purees, dried Coconut
Processed vegetables
Instant mash potatoes, restaurant salad
bars, dried Vegetables, canned or
pickled vegetables, salad dressings,
purees
Processed meats
Sausage (boerewors), cold meats, pate
Puddings
Fruit fillings, gelatin
Grain products
Cornstarch, gravies, noodle rice mixtures
Jams, jellies
Jams, jellies
Snack foods
Dried fruit snacks
Soups
Dried or canned soups
Sweet sauces/syrups
Molasses, pancake syrup, corn or maple
syrup
Symptoms and Signs
Many symptoms and signs can be seen following ingestion of
sulphites. Reactions can be as mild as a throat irritation, to
life-threatening bronchospasm and/or shock. Coughing and/or
bronchospasm are the most common reactions seen. Other
reactions seen include urticaria and exacerbation of eczema. A
variability of response occurs among sensitive patients depending on
their degree of sensitivity to the sulphites and whether the sulphite is
in a bound or unbound form. Time to onset of symptoms following
ingestion of a sulphite preservative can vary from 5 mins to 30 mins.
Some patients improve spontaneously within 30 minutes, but many
will remain unchanged for even longer. Those who are symptomatic
will require immediate treatment.
Pathophysiology
The pathophysiology of sulphite sensitivity is not absolutely clear.
Sulphite-sensitive asthmatics have decreased levels of sulphite
oxidase. This is a enzyme required for metabolism of sulphur
containing amino acids, and levels vary in different tissues. This may
explain why greater levels of sulphite can be ingested than inhaled as
the lung has lower levels of sulphite oxidase than the liver. Some
researchers postulate that the sulphite is eructed as sulphur dioxide
fumes which then stimulate afferent fibres in the respiratory tree. A
very small group of patients are sensitive to sulphite preservatives via
an IgE mechanism.
Balsam containing foods
Citrus fruits
Cola
Chocolate
Spices including Vanilla
Tomatoes
++++++++++++++++++++++++++
Soy containing products.
*Soy is a natural estrogen. Estrogens are contraindicated.
Cholesterol must be < 300 daily.
Musts
Carbohydrate intake must be 60 -65 % of daily intake. >300 grams daily.
Must have carbohydrate a minimum of every 2-3 hours around clock.
Keep Fat intake low If there is kidney involvement fats should be <30 % daily.
Protein should follow the RDA during remission.
6-8 8 oz glasses of water daily
Folate supplementation (if using antiseizure medication)
Magnesium supplementation (if using diuretics)
Magnesium along with 400 units D enable prope calcium absorption in acute
porphyria..
*1750 magnesium to 2,000 calcium w/ 400 UI Vitamin D
Niacin (time released capsules may be used for controlling cholesterol levels.
SOURCE:
Sheryl Wilson MNS RD [HCP}
++++++++++++++++++
Sources of Sulphite Exposure
These include industrial air pollution, foodstuffs, patient medications
and cleaning agents. Sulphite sensitive asthmatics are acutely
sensitive to very small amounts of inhaled sulphite. Severe reactions
have been recorded to minute amounts found in air pollution and
inhaler medications. A sulphite sensitive nurse developed acute
bronchospasm walking into a room where patients were being
nebulized with a sulphite preserved bronchodilator. These patients
can often tolerate a greater concentration of ingested sulphite.
Many foodstuffs may contain sulphite preservatives. The most
important are soft-drinks, dried fruits, cold meats, wine and beer.
Some restaurants may keep their salads fresh with a sulphite
preservative.
Diet and Nutrition in Porphyria
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.
SOURCE:
Karl E. Anderson MD
University of Texas (Medical Branch),
Galveston, Texas.
+++++++++++++++++++++
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.
SOURCE:
Karl E. Anderson MD
University of Texas (Medical Branch),
Galveston, Texas.
+++++++++++++++++++++
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.
SOURCE:
Karl E. Anderson MD
University of Texas (Medical Branch),
Galveston, Texas.
+++++++++++++++++++++
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.
SOURCE:
Karl E. Anderson MD
University of Texas (Medical Branch),
Galveston, Texas.
+++++++++++++++++++++
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.
SOURCE:
Karl E. Anderson MD
University of Texas (Medical Branch),
Galveston, Texas.
+++++++++++++++++++++
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.)
Alcohol
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.
SOURCE:
Karl E. Anderson MD
University of Texas (Medical Branch),
Galveston, Texas.
+++++++++++++++++++++
Fber 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 maycontain chemicals that in large amounts can stimulate heme
and porphyrin synthesis), and highintakes 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.)
SOURCE:
Karl E. Anderson MD
University of Texas (Medical Branch),
Galveston, Texas.
+++++++++++++++++++++
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.
SOURCE:
Karl E. Anderson MD
University of Texas (Medical Branch),
Galveston, Texas.
+++++++++++++++++++++
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.
Dietary guidelines for healthy People
Several widely-known dietary guidelines are described here. None of these is a
complete dietary plan.
The "Basic Four" Plan. In 1956 the U.S. Department of Agriculture, in response
to a need for simple
and specific guidelines that Americans could use in planning diets that would
meet the RDA's for
essential nutrients, established four basic food groups. They recommended
specific numbers of servings
from each food group as part of a well-balanced diet.
Daily Servings
Age Group
Milk and milk
products
Meat
Fruits and vegetables
Breads and
cereals
Children less than 9
years
2-3
2
4
4
The four food groups differ in nutrient content.
Foods within a given food group also differ and do not
all provide equivalent amounts of the same nutrients. For example some fruits
and vegetables are
particularly good sources of vitamin C, while others are especially rich in
carotene (the precursor of
vitamin A).
It is important to recognize that when adhering to the basic four plan there can
be wide variation in nutrient intakes from day to day.
This is particularly true for vitamins and other micronutrients.
This plan recommends servings that should be part of a healthy diet. The plan
itself is not a total diet.
Eating only the recommended number of servings from the four basic food
groups may not provide an
adequate diet.
Such a diet could be deficient in calories, vitamins A and E, riboflavin, niacin,
folate,
magnesium, iron and zinc, for example.
Additional servings of foods within the plan and additional
foods may need to be consumed to provide adequate amounts of all nutrients.
The "Basic Four" Plan remains a practical, noncontroversial and easily
understood guideline which can
serve as the basis of a healthful diet.
SOURCE:
Karl E. Anderson MD
University of Texas (Medical Branch),
Galveston, Texas.
+++++++++++++++++++++
National Research council Guidelines. The NRC, which is the action arm of the
National Academy of
Sciences, issued two somewhat conflicting sets of dietary recommendations in
1980 and 1982. The
two different advisory panels that prepared these guidelines were concerned
about the broad issues of
diet and health, including the prevention of cancer and arteriosclerosis.
SOURCE:
Karl E. Anderson MD
University of Texas (Medical Branch),
Galveston, Texas.
+++++++++++++++++++++
A report in 1980 entitled "Toward Healthful Diets" concluded that no specific
dietary recommendations
were appropriate for the entire U.S. population. Rather, the report recommended
the following advice
on how to achieve a balanced selection of foods and a moderate and adequate
consumption of
nutrients. This advice is consistent with the Basic Four Plan.
SOURCE:
Karl E. Anderson MD
University of Texas (Medical Branch),
Galveston, Texas.
+++++++++++++++++++++
1.Select a nutritionally adequate diet from foods available, by consuming each
day appropriate
servings of dairy products, meats or legumes, vegetables and fruits, and
cereals and breads.
2.Select as wide a variety of foods in each of the major food groups as is
practicable in order to
ensure a high probability of consuming adequate quantities of all essential
nutrients.
3.Adjust dietary energy intake and energy expenditure so as to maintain
appropriate weight for
height; if overweight, achieve appropriate weight reduction by decreasing
total food and fat
intake and by increasing physical activity.
4.If the requirement for energy is low (e.g. reducing diet), reduce consumption
of foods such as
alcohol, sugars, fats, and oils, which provide energy but few other essential
nutrients.
5.Use salt in moderation; adequate but safe intakes are considered to range
between 3 and 8
grams of sodium chloride daily.
SOURCE:
Karl E. Anderson MD
University of Texas (Medical Branch),
Galveston, Texas.
+++++++++++++++++++++
A report in 1982 entitled "Diet, Nutrition and Cancer" focused on the putative
relationship
between diet and cancer. Specific recommendations about certain foods were
made.
1.Reduce intake of both saturated and unsaturated fats, from approximately
40to approximately
3074757f total calories.
2.Include fruits, vegetables and whole-grain cereal products in the daily diet,
especially citrus fruits
and carotene-rich and cabbage family vegetables. Avoid high-dose
supplements of individual
nutrients.
3.Minimize consumption of cured, pickled, and smoked foods.
4.Drink alcohol only in moderation.
SOURCE:
Karl E. Anderson MD
University of Texas (Medical Branch),
Galveston, Texas.
+++++++++++++++++++++
The latter recommendations have been controversial.
The report itself stated "The data are notsufficient to determine the contribution
of diet to the overall cancer risk or the percent reduction in risk
that might be achieved by dietary modification."
The emphasis of cured and smoked meats was not appropriate, in the opinion of
many.
Few meat products in the U.S. are preserved by heavy smoking, salting or
nitrate treatment.
Liquid smoke flavorings are extensively used; these contain little if any
benzo(a)pyrene, the principal carcinogen in smoke. (Benzo(a)pyrene is one of
the chemicals known as "polycyclic aromatic hydrocarbons" and found in
cigarette smoke and in charcoal broiled meats.
Thesechemicals can stimulate the heme biosynthetic pathway in the liver and
might be harmful in porphyria.)
Meats are preserved primarily by refrigeration rather than salting, and the
addition of nitrate is closely
regulated.
Curing solutions for bacon contain ascorbate (vitamin C) or erythorbate to
prevent formationof nitrosamines.
The capacity of bacon to produce nitrosamines during frying is routinely
monitored by
the FDA.
Therefore, there is no evidence that cured or smoke meats routinely sold in U.S.
supermarkets are hazardous. Similar recommendations with regard to
consumption of fats, fruits and
vegetables have been made by other organizations, including the American
Heart Association, theAmerican Cancer Society, and the Surgeon General.
Some others feel that such recommendationsshould apply only to individuals or
groups known to be at risk for diseases such as arteriosclerosis,hypertension, or
cancer, rather than to the general population.
SOURCE:
Karl E. Anderson MD
University of Texas (Medical Branch),
Galveston, Texas.
+++++++++++++++++++++
Strategies for changing diet
Some approaches useful in enhancing the motivation of individuals to change
their diets are listed
below. (Approaches described here for encouraging dietary changes are very
general and do not
include more specific approaches that are useful, for example, for weight
control.) Similar strategies for
altering health behavior are used to encourage individuals to make other
changes that are favorable to
their health (stopping smoking, for example).
SOURCE:
Karl E. Anderson MD
University of Texas (Medical Branch),
Galveston, Texas.
+++++++++++++++++
Changing dietary lifestyle
1.The positive health effects of the recommended dietary change, and the
negative effects of not
making the change, should be discussed by the patient, the physician and
the dietitian.
Motivation is increased if the focus is on health consequences in the near
future rather than the
distant future.
2.Motivation is enhanced by using individual examples of the health benefits of
changing diet rather
than only providing general or statistical information.
3.Advice should be concrete and specific, and include food lists, meal plans,
etc. Such written
material helps an individual develop a specific plan for making a behavior
change. It is generally
best if specific face-to-face advice is given by a physician and a dietitian.
4.Goals should be realistic given the circumstances of an individual.
5.An individual should not be overly discouraged if initially there are problems
in accomplishing
dietary goals. It is sometimes advisable to start with small changes that are
easily achieved and
then build progressively on initial success in order to achieve larger changes.
6.Self-monitoring before and after making a dietary change helps to identify
incentives,
disincentives, and situations that interfere with accomplishing a change.
7.An individual that is serious about making a long term dietary change needs
to free their home of
foods not on their diet, stock up on recommended foods, and learn to avoid
situations which
lead to eating foods other than those on the recommended diet.
8.Enlisting the support of family members, roommates, or coworkers can
provide encouragement
and reminders, and praise when goals are achieved.
SOURCE:
Karl E. Anderson MD
University of Texas (Medical Branch),
Galveston, Texas.
|
