There are several factors that can help protect against hypertension. But when the potassium to sodium ratio of your diet is poor, these factors are of little help. Some recent posts (1, 2) discussed how normally protective fruits and vegetables can be made to fail by a poor ratio. Exercise and leanness are usually felt to prevent hypertension. But they too can be undermined by a poor dietary ratio of potassium to sodium.
A recent article (3) brought back memories of a classic article (4) from 1981. This spring there was an article (3) concerning hypertension in Yazd. This is an urban center close to a rural area in Iran that had a high incidence of hypertension in a 1981 report.
What was unique about the rural group, the Qash'qai, was that they remained lean and very physically active into old age. Nonetheless they had a high incidence of hypertension, although not as high as the thin, physically active tea garden workers of India (1) discussed a few weeks ago.
Exercise and leanness usually protect against hypertension. They are associated with lower blood pressure. However, if the basic principle of having a high potassium to sodium ratio in your food is not followed, you will still have a strong chance of developing hypertension.
Exercise And Leanness Are Not Enough
In the 1981 report (4) researchers discussed how blood pressure in the Qash'qai went up with age the same as in a typical urban Western society. The Qash'qai however were nomads who remained lean throughout their life, traveling great distances on foot while shepherding their herds of sheep and goats. Even so, they had an incidence of hypertension of over 20%.
The researchers determined the diet of the Qash'qai by a food frequency questionnaire. But they also confirmed the sodium and potassium content of the diet with measurement of urinary potassium and sodium, which correlates well with the dietary content. The urinary ratio was 0.28 in men and 0.31 in women.
Examination of their diet showed they added salt to almost all of their food, either during preparation or at the table. 100% of the subjects ate bread. For many it was all they ate for at least one meal. Approximately half of the nomads ate rice, 37% ate vegetables and only about 28% ate meat, with 17% eating dairy and 17% eggs.
The researchers measured the sodium and potassium content of the bread and rice. They found very high ratios of sodium to potassium in each of their samples. Also they noted that salt was added to almost every dish.
Exercise And Leanness And No Salt
This is in great contrast to the centenarians that we have discussed in the past. In Sicani (5) and in Sardinia there are a great number of centenarians. They also remain physically active in a mountainous region and maintain a normal weight. However, in contrast, they do not add salt to their food.
In the Qash'qai report the researchers correlated blood pressure with age and body weight. They found that body weight did not increase with age as it does in the West, even though blood pressure increased the same as in the West. Leanness and physical activity do not fully protect against the hypertension resulting from a poor ratio diet.
Rural And Urban Diet With Same Ratio
In the more recent report about Yazd (3) it appears that the sodium and potassium in the diet have not changed. This was an urban environment in which the amount of dietary sodium and potassium had remained in the same ratio as in the rural population.
The percentage of hypertension was twice as great in the Yazd participants as it had been in the Qash'qai. In Yazd, 40% of people were hypertensive (with more than half of them previously undiagnosed). In the Qash'qai, hypertension had been present in at least 22% of men and 29% of women. The Yazd study did not report on physical activity or leanness, but urban dwellers are generally less active and less lean than rural nomads.
The Yazd study included more young people than old (as did the Qash'qai study), but did not report blood pressure by age group. This lack of age group information and the 33 years between reports make it difficult to compare the two groups. Nonetheless, the Qash'qai study shows that exercise and leanness are not enough to fully prevent hypertension. Compared to an urban lifestyle, the leanness and physical activity of a rural nomad lifestyle may cut in half the chance of hypertension.
But a poor potassium sodium ratio will still lead to hypertension for many who exercise and stay lean. The first and most basic way to prevent hypertension and its associated cardiovascular problems is to eat a diet with a high potassium to sodium ratio.
Exercise and maintaining a normal weight can help when the diet is right. With a high ratio diet, normal blood pressure can be maintained into old age, as with many rural indigenous people (6). When the diet is not right, exercise and weight control will help only a little.
3. Sodium and potassium intake of urban dwellers: nothing changed in Yazd, Iran. Mirzaei M, Soltaniz M, Namayandeh M, GharahiGhehi N. J Health Popul Nutr. 2014 Mar;32(1):111-7.
4. Blood pressure of Qash'qai pastoral nomads in Iran in relation to culture, diet, and body form. Page LB, Vandevert DE, Nader K, Lubin NK, Page JR. Am J Clin Nutr. 1981 Apr;34(4):527-38.