"Our results demonstrate for the first time that merely by partially reversing the acidity of the diet, bone mass increased rapidly and in amounts that are within the range of increases produced by common FDA-approved medicines," said co-author, Prof. Reto Krapf of the University of Basel, Switzerland.
Osteoporosis is estimated to affect about 75m people in Europe, the USA and Japan. According to the International Osteoporosis Foundation, the total direct cost of osteoporotic fractures is €31.7bn in Europe, and 17.5bn in the US (2002 figure). The total annual cost of osteoporosis in the UK alone is over £1.7bn (€2.5bn), equivalent to £5m (€7.3m) each day.
It is well established that potassium is important for regulating pH levels in body fluids, blood pressure, muscle and nerve cells, osmotic pressure and water balance. The mineral is commonly used in diet products and meal replacement bars because it is particularly critical for individuals who are dieting or taking diuretics.
The new research, to be published in the November issue of the Journal of the American Society of Nephrology, claims to be the first to report the benefits of pH regulation with potassium citrate and the subsequent effects on bone mineral density (BMD).
The researchers, led by Prof. Krapf, recruited 161post-menopausal women (average age 59) with known low bone mass, and therefore considered to be at high risk of fracture. The women were randomly to one of two intervention groups - potassium citrate supplement as tablets (Urocit-K, 30 millimoles), which provides a very small amount of alkali, or an equal dose potassium chloride supplement (none alkaline). BMD measurements were performed using dual-energy x-ray absorptiometry at baseline, at six months, and finally after one year of supplementation.
At the end of the study, women taking the potassium citrate supplement are reported to have a significant, one per cent increase in BMD in the vertebrae of the lower back (lumbar spine), compared to baseline.
However, the bone mineral density of the lumbar spine of women taking the potassium chloride supplement (none alkaline) was found to have significantly decreased after one year of supplementation, by about one per cent.
Increases in bone mass also occurred in the hip, are also reported by the researchers.
Women taking the base supplement were also found to have lower amounts of calcium excreted in the urine. Lower calcium excretion was interpreted as greater calcium retention in the skeleton.
The mechanism behind the apparent benefits is proposed to be by the alkaline supplement neutralizing the high acidity of the modern Western diet.
"In the modern diet, acid is generated from foods like dairy products, grains, and meats," explained Prof. Krapf in a statement. "Previous studies have found that the kidney does not quite keep up in removing this excess acid load, resulting in mildly elevated blood acidity.
"Taking a base supplement in this study resulted in sustained reduction of acidity of body fluids, assessed by urinary acid and citrate tests, such that in essence, the supplement modified the effects of the normal diet, making it mimic the low acid content of the ancestral diet of nearly all fruits and vegetables," he said.
Professor Krapf added that the researchers had been surprised by the scale and strength of the effect from the alkaline (basic) potassium citrate supplement.
Significant further research needs to be performed to confirm these effects in other populations and age groups at increased risk of osteoporosis before any recommendations can be made.
"However, given the safety and extremely low cost of this agent, these results should be very encouraging to government agencies regarding funding for future trials," concluded Dr. Krapf.