As healthy and as long-lived as Norwegians are, they are plagued by one baffling disease: Osteoporosis. As a woman who has lived here for part of her childhood and all of her adulthood, this is something to be concerned about. Is it genetic? Is it dietary? We may have the answer, finally. Good dietary habits when I was a child in Norway included a tablespoon of cod liver oil. As a child, I actually liked the stuff. Didn't like fish, but I didn't mind that spoonful of omega 3's and vitamin D, intended to compensate for the lack of sunshine. (The rule is to take cod liver oil or "tran" in all months with an R in it. There is also the rule not to fish in months without an R in it, so those two rules dovetail nicely.) As an adult I can't stand straight "tran" any more and get my fish oil in capsule form.
In the years since, Norwegian researchers trying to understand the national epidemic of broken hips have proposed many theories: Sedentary lifestyle, not enough milk or calcium in the diet, not enough fish in the diet, not enough sunshine. However, in comparison to countries with a similar population or lifestyle, none of those theories held water.
Water itself may be the reason.
Most fresh water comes from underground, moving in aquifers that give off minerals to the water. All over the world, humans dig wells to get to this water source. But in Norway, our main source of drinking water is surface water. We get it from lakes and reservoirs replenished by rainfall. And that water has hardly any minerals in it since it doesn't pass through rock.
85 % of Norway's drinking water comes from surface water. And the current best theory about why our rate of osteoporosis is so high is the lack of mineral content in our water, especially the lack of magnesium.
It is the one thing that makes sense to me. I have already discovered that magnesium helps my digestion and bowel motility. Now I'm going to double my intake in hopes of compensating for decades of drinking fresh, clear and cold water straight from my tap.
(Re current best theory: PDF article in Norwegian with introductory paragraph in English.)