BMD (Bone Mineral Density) In Finland

Finland had great success in reducing its rate of strokes by improving its potassium sodium ratio. This improved ratio should also help its rate of osteoporosis. In a previous post we discussed how Finland had a lower hip fracture rate than any of the other Scandinavian countries. But that doesn't necessarily mean they reduced their osteoporosis. Maybe they changed things so people didn't fall so often or fall so hard. A better way to tell if they improved osteoporosis than measuring hip fracture rate would be to check their bone mineral density (BMD).

DXA Measures BMD

DXA Machine
DXA measures BMD

The bone mineral density is usually measured by a scan called DXA (previously DEXA). It is a good way to estimate the loss of bone strength and the risk of a fracture from osteoporosis. However, because DXA is not readily available in many countries, researchers study hip fracture rates.

The highest rates of hip fracture are found in the Scandinavian countries. However, there is one Scandinavian country that is an exception – Finland. Countries farther south in Europe have a lower rate than most of Scandinavia, but about the same as Finland. Finland would be expected to have many of the same external factors leading to hip fracture as the rest of Scandinavia. Slippery conditions from ice and snow, hard surfaces to fall on, and other social and economic factors would be more similar to the other Scandinavian countries than to southern Europe.

Increased BMD In Finland From Improved Potassium Sodium Ratio In Food

However there is one big difference between Finland and the rest of Scandinavia. The potassium to sodium ratio in their diet has been improving since they started a country-wide program in the 1970s. We discussed previously how Finland's lower hip fracture rate could be from this change in diet. But if it is from diet, you would have to show that their bones were stronger. The best test we have today to show how strong bones are is the DXA, which measures bone mineral density (BMD).

Just this year a study (1) of the BMD of women over 70 years of age was done in Finland. It showed the bone mineral density at the hip has increased substantially in the Finnish women. The authors did not give a definite reason for the improvement in BMD, but stated that it could be due to a number of factors, giving improved social and economic resources as possible reasons. However the biggest social change in Finland in recent decades has been the change in diet leading to an improved potassium sodium ratio. This change is consistent with the basic science of bone strength. Many other social changes, such as the increased smoking in women in Finland, would lead to weaker bones.

This change in diet is the most likely explanation for the improved bone mineral density in Finland. This four decade long change in diet did not occur in the rest of Scandinavia. As Finland's potassium sodium ratio improved their BMD and hip fracture rate improved. But there was no such improvement in the rest of Scandinavia. In Finland women consume under 3 gm of sodium daily (2) and in the remainder of Scandinavia they consume over 4 gm of sodium daily (3). In Finland the rate of hip fracture is less than 40% of that in Norway.

______________________________________________
1. Improved femoral neck BMD in older Finnish women between 2002 and 2010. Uusi-Rasi K, Karinkanta S, Heinonen A, Sievänen H. Maturitas. 2013 Jul;75(3):241-5. doi: 10.1016/j.maturitas.2013.04.001. Epub 2013 Apr 30.

2. 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.

3. 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.