110 Joel Fuhrman, M.D.acid secreted by the stomach linked to blood type? Was this ever sci-
entifically investigated? He produces no study that illustrates this.
D'Adamo needs to review a little basic physiology; for one thing,
acid doesn't digest protein anyway. Pepsin does.
Glands in the mucous membrane lining of the stomach store
pepsinogen, an inactive protein. The hormones gastrin and secretin
stimulate the release of pepsinogen into the stomach, where it is
mixed with hydrochloric acid and converted into its active enzyme,
pepsin. Acid merely creates the optimal pH (between 2 to 4) to acti-
vate pepsinogen and change it into its active form, pepsin.^46 If it were
true, as D'Adamo claims, that a certain blood type could secrete a lit-
tle more or less acid, it would have little or no effect on the ability to
digest animal protein. Except in the elderly, low acid levels in the
stomach are exceedingly rare.^47 It is almost unheard-of that individ-
uals can't secrete enough acid to effectively lower stomach pH to
convert pepsinogen to pepsin. One concerned about having insuffi-
cient stomach acid could always draw a serum gastrin, a fairly reli-
able method of detecting bona fide hypochlorhydria, or low stomach
acid.^48
Having AB blood type with lower gastric acid secretion wouldn't
make eating meat more fattening anyway, contrary to what D'Adamo
claims. The incompletely digested proteins would pass on down and
get degraded by intestinal bacteria, reducing the absorption of amino
acids and contributing to caloric loss and weight loss, not weight
gain.
Do blood type Os have a tendency toward low thyroid function
because, as D'Adamo states, "type Os tend not to produce enough io-
dine"? First of all, our bodies do not produce any minerals, such as
iodine. Iodine, as welf as other minerals, can be absorbed only from
what we consume in our diet. And if that is not bad enough, the onb
medical study I could find regarding the claim that type Os have
tendency to low thyroid function illustrated the exact opposite. Ex
cessive thyroid function was found to be more common in type O in
dividuals, and low thyroid function was more common in type As.^4 'Then D'Adamo states that foods such as salt and liver encourage
weight loss in these type Os. Is he serious?
One could go on and on explaining his errors and omissions, but
the main point is that the book is too inaccurate to take seriously,
and despite the real relationship of certain blood types and genetic
risks, we all need to minimize our risk of heart attack and cancer by
eating the most nutritionally dense and phytochemically strong diet