Many scientific studies show the potassium sodium ratio to be critical for the prevention of hypertension and strokes. Additionally, the ratio is important for the prevention of osteoporosis, with a higher ratio leading to improved bone density. But the evidence for its role in osteoporosis is not as strong as it is for hypertension. There are several reasons why this is so. Although researchers have done an extensive amount of work on osteoporosis, large gaps in our knowledge remain concerning the relation of the minerals, hormones and other factors involved. What is needed is a systems approach, such as that done for hypertension by Drs. Guyton, Young and Hall.
Problems With Studies Of Modern Indigenous Groups
Authors have published a large number of studies of indigenous populations for hypertension. But, there have not been as many done for osteoporosis. And those that were done had mixed results. One problem is the lack of vitamin D and the lack of protein in many modern indigenous diets. Both have a major effect on bone density.
Because today's methods to measure bone density were not present in the 1950s and 1960s, there were not the same kinds of studies for osteoporosis as there were for hypertension during that period. But more recently, researchers are beginning to do such studies. However, there are fewer indigenous groups uninfluenced by a modern diet than there were in the 1950s and 1960s.
Two Recent Studies Of Bone Density
Two recent studies discuss bone density and osteoporotic fractures in some modern indigenous groups. Researchers examined the Colonos and the Shuar of Amazonian Ecuador with calcaneal quantitative ultrasound (QUS) to determine their bone mineral density (1). Both groups showed increased bone density in comparison to other groups.
Since this was a study to determine norms for future comparison, it did not report factors contributing to the increased density. However, outside influences have affected the Shuar and other indigenous groups from the Amazon increasingly since the 1970s. Thus, researchers already may have lost the ability to study their natural diet.
Indigenous Diet Already Lost
For example, researchers examined the Aboriginals and Torres Strait Islanders for both fracture incidence and bone mineral density (2) (3). The researchers compared the two groups to Caucasian Australians. Both of these groups had denser bone and fewer fractures than the Caucasians at the same age. However, it is not because of diet. The diet of the Aboriginals and Torres Strait Islanders is generally very deficient, and is much like a modern diet. This is the problem that researchers will face when studying modern indigenous groups today. There will be very few groups uninfluenced by the modern diet.
Factors Other Than Diet
While such bone density studies are interesting, studies of indigenous groups will be unlikely to provide helpful dietary evidence. Multiple other known factors beyond diet contribute to increased bone density. These other factors that increase bone density include a low incidence of smoking and excessive alcohol, and increased physical activity, especially weight bearing. Consequently, these factors will influence bone density far more than minor dietary differences.
With exposure to the modern world, indigenous groups shift to a modern diet. Any dietary differences will be minor. To accurately determine how much diet, physical activity and the various other factors play a part in osteoporosis, studies of indigenous groups will play only a minor role. A systems approach like that done by Drs. Guyton, Hall and Young for hypertension will be needed.
What Is Needed
The extensive experimental and integrative work done by Drs. Guyton, Hall and Young is lacking in osteoporosis. Much like hypertension, osteoporosis involves multiple interactions. For osteoporosis, there are interactions between several hormones, minerals, and nutrients. Each of these interacts with the kidneys and bones to balance the calcium deposition in bone.
Potassium, especially in the form found in high potassium foods, organically bound to citrate and other bicarbonate precursors, has a positive effect on calcium resorption and deposition. Sodium leads to calcium loss in the urine. However, researchers of osteoporosis have not as thoroughly worked out the metabolic pathways that were discovered in hypertension.
In contrast to indigenous studies, there are an increasing number of population based clinical trials with modern populations. These help lend weight to the high potassium food contribution to preventing and correcting osteoporosis. Other important evidence comes from animal and human experimental work. We will discuss some of these in future posts.
1. Normative calcaneal quantitative ultrasound data for the indigenous Shuar and non-Shuar Colonos of the Ecuadorian Amazon. Madimenos FC, Snodgrass JJ, Blackwell AD, Liebert MA, Cepon TJ, Sugiyama LS. Arch Osteoporos. 2011 Dec;6(1-2):39-49. doi: 10.1007/s11657-011-0056-x. Epub 2011 May 21.
2. Fractures of the femoral neck in Australian Aboriginals and Torres Strait Islanders. MacIntosh DJ, Pearson B. Aust J Rural Health. 2001 Jun;9(3):127-33.
3. Increased bone mineral density in Aboriginal and Torres Strait Islander Australians: impact of body composition differences. Maple-Brown LJ, Hughes J, Piers LS, Ward LC, Meerkin J, Eisman JA, Center JR, Pocock NA, Jerums G, O'Dea K. Bone. 2012 Jul;51(1):123-30. doi: 10.1016/j.bone.2012.04.011. Epub 2012 Apr 27.