Dr Arthur Coca, a leading American allergist, stated
that his wife once reported that her pulse raced after eating certain foods. On
this simple observation this great, pioneering doctor — who bridged the gap
between clinical ecology and conventional immunologically-oriented
allergy work comfortably — built a very interesting technique for detecting
allergies, especially to foods.
Because Coca identified clearly a group of patients
who had food allergies, ascertained that it ran in families and found no
antibodies or other humoral agents to explain the
reaction (nor yet have been), he called it familial non-reaginic
food-allergy. A further characteristic of this type of allergic reaction is
that it frequently raises the pulse rate. It is a very widespread phenomenon in
the population: Coca put it as high as 90 per cent on circumstantial evidence.
He gave two important factors as the basis of his
discovery, pointing out the dependability of the heart rate as a constant, if
all other factors remain equal:
The daily pulse
range (the difference between the slowest and fastest pulse rate of the day) is
rarely greater than 16 beats per minute.
maximum, remarkably, does not vary by more than two beats per minute.
Coca goes on to say that if the daily range of the
pulse exceeds 20 and the daily maximal counts per minute vary by more than two
beats, the patient is practically certainly affected with an allergy of the nonreaginic type. Furthermore, if the maximal count is 88
or higher, this is good corroborative evidence and the diagnosis can be upheld.
It must be pointed out that all this refers to a resting pulse rate and that
there must be no other manifest clinical condition (such as a fever, heart
disease, thyroid excess, anaemia, etc.) that would
account for a high or variable pulse rate.
As Coca observed, a patient with allergies may
present a completely normal pulse-record for several days on an unrestricted
diet, though this is rare. We now know that if this occurs it is due to the ‘masking’ phenomenon (see hidden allergy).
Coca’s method has two aspects. First, he advocates a
charted survey of the pulse over several days, the patient taking his or her
pulse before getting out of bed in the morning, before each meal, twice after each
meal (30 and 60 minutes afterwards) and then on retiring. This record may then
be studied in the light of the above criteria. The chart we use in my own
clinic is shown in Table below. It is the chart of a 55-year-old woman with
arthritis. It shows a range of 28 beats. Also you may note that each time she
ate banana her pulse rate increased sharply, and she did indeed turn out to be
allergic to banana. She was also allergic to tea, milk, egg and beef, but these
caused no reaction on this survey, presumably due to the masking effect.
It is difficult to identify specific allergens by
means of a chart such as this. It serves only as a general, guide to the case.
If by chance, however, it shows periods of normal pulse rate (such as on Day 1
and Day 6), the foods eaten before these periods may be selected as ‘safe’ and
if the patient concentrates on those foods he or she may then have a steady
baseline upon which to project individual feeding tests.
Coca carried out individual food tests on the basis
of five small meals a day, consisting of one single food to be tested at each
sitting. He recommended small portions so that the reaction, if there is one,
clears more quickly. The resting pulse is used and must be counted for a full
minute. It is recorded before ingesting the food and again 30, 60 and 90
minutes afterwards. Naturally the patient should avoid any provocative
activities in the interim, otherwise confusion may
occur, though it is not necessary to sit still for the entire one-and-a-half
Safe foods may be used cumulatively. That is, foods
that do not raise the pulse may be eaten along with the new food being tested.
The time of day and also the sequence in which foods are tested is unimportant,
Coca stated, though today we benefit by being able to suggest avoiding foods
from the same family within the same two-day period, in case inadvertent
cross-reaction and masking occurs.
Essentially this is a simple method and can
easily be carried out by the individual on him- or herself. However there are
one or two pitfalls. For example, cumulative productive reactions can occur.
That is, a food that has little or no effect at first may, if eaten repeatedly
as a ‘safe’ food, steadily increase the pulse rate. This problem can usually be
sorted out by rotating safe foods.
Environmental factors may also confuse the
issue. It may appear that a food is
causing a reaction when in fact it is due to something in the room at the time
of testing. It is important to keep
conditions as consistent as possible, to avoid this difficulty.