High potassium foods prevent hypertension, osteoporosis and kidney stones. The evidence for this is strong enough that the Institute of Medicine has recommended getting 4700 mg of potassium and less than 1500 mg of sodium a day. In the past several posts we discussed the evidence for high potassium foods preventing hypertension, and the evidence for the health problems that accompany hypertension. The evidence is overwhelming. Likewise, the evidence for the prevention of osteoporosis, and its associated health problems, such as hip fracture, is also strong, although not as strong as it is for hypertension.
Specifically, the main shortcoming in the evidence for osteoporosis is that there has not been the kind of systems research for osteoporosis that was done for hypertension. The dietary studies of indigenous populations, that were so helpful in studying hypertension, were not done for osteoporosis. As a result, the opportunity to perform them in the future is limited.
Population Based Studies
The population based studies done in Finland and Japan for hypertension have not been done for osteoporosis. Hopefully, with the increasing incidence of osteoporosis in the world, they will be done in the near future. In the meantime, there are studies of surrogate markers for osteoporosis that lend weight to the potassium sodium ratio in food being critical to the prevention of osteoporosis. By looking at studies related to osteoporosis, and comparing them to separate dietary studies of the same populations at roughly the same time, some correlations can be done.
Surrogate Markers For Osteoporosis
There are several surrogate markers for osteoporosis. One of the most important is fragility fracture. A fragility fracture is a fracture that would not occur in normal bone from the amount of force involved in the mishap. The three main fragility fractures are hip, vertebrae and wrist fractures. Other surrogate markers often used for osteoporosis are BMD from DEXA scans, calcium balance, urinary calcium and urinary bone breakdown markers. However, none of them are perfect.
Fragility fractures are important since they are one of the end results that we try to avoid by increasing bone density. But the fractures are the result of multiple factors, not just weak bones. The other factors involved in osteoporosis include genetics, environmental risks, low body mass, low calcium and vitamin D intake, smoking, excessive alcohol intake, inadequate physical activity, and obesity. And these all play roles that have not been well characterized yet.
In addition to these factors, most fragility fractures result from falls. So anything contributing to falls, such as icy conditions, rough terrain, balance disorders, or other illnesses can cause an increased incidence of fragility fractures. Most studies correct for these considerations by excluding traumatic fractures. But if the fracture occurs after a fall or other factor that should not have caused a fracture in normal bone, it is considered a fragility fracture.
Hip Fracture In Scandinavia
The most common fragility fracture is a hip fracture. And the highest incidence of hip fractures is in the Scandinavian countries (1). Denmark, Sweden, Austria and Norway have the greatest incidence among women. Southern Europe has a lower incidence. Generally, as you move south in Europe, you have fewer hip fractures. One exception is Finland, a Scandinavian country with an incidence about the same as France, one of the more southern nations.
In this case, Finland provides further evidence of the value of the potassium sodium ratio in reducing susceptibility to hip fractures. In Finland the incidence of hip fracture in people over 50 years of age has been decreasing since 1997 from 516 per 100,000 to 383 in 2010 (2). In contrast, the incidence in Norway has been relatively unchanged at 1010 per 100,000, despite a government program to reduce fractures (3).
Higher Potassium Sodium Ratio To Reduce Hip Fractures
Although the increased hip fracture rate in Scandinavia could be explained by the icy conditions much of the year, the far lower rate of fracture in Finland lends support to the idea that an improved potassium sodium ratio results in stronger bones. Finnish women consume under 3 gm of sodium daily (4), whereas in the 3 highest fracture rate Scandinavian countries they consume over 4 gm of sodium daily (5).
Dietary Changes
Previously, we discussed in a post the improved potassium sodium ratio in the diet that occurred in Finland to reduce hypertension. And this same diet appears to reduce hip fractures. However, none of the other Scandinavian countries have changed their diet. So the improvement of the potassium sodium ratio that occurred since 1970 in Finland may have improved their hip fracture rate relative to other Scandinavian countries.
There are too many differences between nations to make a definitive comparison, but the Scandinavian nations have a relative uniformity. This makes the lower rate of fracture in Finland food for thought. If future studies show an increased BMD in Finland that would add further weight to the improved potassium sodium ratio in their diet as a way to reduce osteoporosis.
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1. A systematic review of hip fracture incidence and probability of fracture worldwide. J. A. Kanis, A. Odén, E. V. McCloskey, H. Johansson, D. A. Wahl, C. Cooper, and on behalf of the IOF Working Group on Epidemiology and Quality of Life. Osteoporos Int. 2012 September; 23(9): 2239–2256. Published online 2012 March 15. doi: 10.1007/s00198-012-1964-3
2. Continuous decline in incidence of hip fracture: nationwide statistics from Finland between 1970 and 2010. Korhonen N, Niemi S, Parkkari J, Sievänen H, Palvanen M, Kannus P. Osteoporos Int. 2013 May;24(5):1599-603. doi: 10.1007/s00198-012-2190-8. Epub 2012 Oct 30.
3. Hip fractures in a city in Northern Norway over 15 years: time trends, seasonal variation and mortality : the Harstad Injury Prevention Study. Emaus N, Olsen LR, Ahmed LA, Balteskard L, Jacobsen BK, Magnus T, Ytterstad B. Osteoporos Int. 2011 Oct;22(10):2603-10. doi: 10.1007/s00198-010-1485-x. Epub 2011 Jan 20.
4. Sodium in the Finnish diet: II trends in dietary sodium intake and comparison between intake and 24-h excretion of sodium. Reinivuo H, Valsta LM, Laatikainen T, Tuomilehto J, Pietinen P. Eur J Clin Nutr. 2006 Oct;60(10):1160-7. Epub 2006 Apr 26.
5. Salt and public health–policies for dietary salt in the Nordic countries. Närhinen M, Cernerud L. Scand J Prim Health Care. 1995 Dec;13(4):300-6.
