"Alkali Load" May Help Conserve Bone and Muscle By Rosalie Marion
Bliss March 11, 2009
Agricultural Research Service
(ARS)-funded scientists have recently reported that compounds in plant foods,
which are alkali-producing, may help preserve bone and muscle mass. Now, a new
ARS-funded study suggests that reducing the acid load that accompanies the
typical high protein diet may also be important.
ARS is the principal intramural scientific research agency of the
U.S. Department of Agriculture (USDA). The
study was led by Lisa Ceglia and
Dawson-Hughes at the
Mayer USDA Human Nutrition Research Center on Aging at
Tufts University, in Boston, Mass.
Diets high in protein and low in fruits and vegetables result in mild
"acidosis" with aging. That's because protein metabolism releases acids into
the bloodstream in amounts that override the alkalinizing effect of potassium
and bicarbonate in plant foods.
The researchers studied results from a group of 19 healthy
individuals, older than 50, who were on a controlled diet. To simulate
consumption of the equivalent of eating about 14 servings of fruits and
vegetables daily, nine of the participants were randomly assigned to receive
3,510 milligrams daily of potassium bicarbonate in capsules. The other 10
participants were assigned to receive matching "placebo" capsules.
Once the volunteers gradually reached the maximal level of daily
potassium bicarbonate or placebo capsules, all 19 participants were
successively given a 10-day low (or high) protein diet followed by a 10-day
high (or low) protein diet, with a five-day “wash out” period in
The researchers wanted to look at both an alkali-producing diet (the
potassium bicarbonate group) and an acid-producing diet (the placebo group).
Blood, urine and calcium absorption analyses were performed after each diet
period, and markers of muscle and bone metabolism were measured.
With increased dietary protein intake, the potassium bicarbonate, or
alkalinized, group--when compared to the placebo group--had reduced urinary
nitrogen excretion, which is an indicator of reduced muscle wasting. The
alkalinized group also had higher levels of IGF-1, a marker of both muscle and
bone conservation, and of calcium absorption--a marker of bone conservation--on
both protein diets, compared to the placebo group.
The study suggests that the net effect of adequate dietary protein on
muscle may be enhanced by reducing its accompanying acid load, according to the
authors. Though not tested in the study, increasing intake of fruits and
vegetables would be another way to increase the alkali potential of the diet,
according to Dawson-Hughes.
The analysis was published in the
Journal of Clinical Endocrinology and