Salt intake – What of Nuns?

Excess salt intake is one of the great issues in preventative medicine. Last year I watched a bus go by, with an advert for reducing salt plastered all over the side. Some restaurants have taken salt cellars off their tables, to protect customers. Many foodstuffs now have their salt content clearly labelled, with high salt content given a red sticker.

Given all of this you would think, would you not, that the case for excess salt consumption causing cardiovascular disease had been made beyond even the slightest possibility of doubt. One of the arguments in support of the dangers of salt consumption (the one that I am looking at in this article), comes from the native peoples living in the Amazon

The Amazon is an extremely low salt environment, and the average salt consumption of those living there is at very low. Several studies have found that the tribes people living in the Amazon have very low blood pressure which does not increase with age. They also have very little in the way heart disease and strokes.

Primitive societies who ingest little or no salt have no hypertension1

Proof, the anti-salt lobby cry, that it is excess salt intake that causes our blood pressure to rise dangerously.

Or is it? When presented with ‘proof’ like this I tend to look for contradiction, rather than confirmation. Are there, I wondered, other populations that fail to demonstrate a rise in blood pressure with age, that do not have a low salt consumption. My attention was drawn to nuns, living in Italy.

‘The powerful effect of psychosocial and acculturating influences on population blood pressure trends seems to be confirmed, through longitudinal observations, in the nuns in a secluded order. After initial observations had been made on culture, body form, blood pressure, diet, and other variables in 144 nuns and 138 lay women, included as a control group, a 30-year follow-up study was undertaken. Most striking were opposite trends noted between the two groups in blood pressure trend. During the follow-up period, blood pressure remained remarkably stable among the nuns. None showed an increase in diastolic blood pressure over 90 mm Hg.’

So, nuns do not develop high blood pressure as they age. What happened to the control women in this study?

‘By contrast, the control women showed the expected increase in blood pressure with age. This resulted in a gradually greater difference (delta>30/15 mm Hg) in systolic and diastolic blood pressure between the two groups, which was statistically significant.’

No difference in diet or salt consumption, yet one population developed the ‘normal’ Western rate of hypertension whilst the other did not. What did the authors of this thirty yearlong study think was the reason for this finding?

‘In conclusion, it seems reasonable to attribute much of the difference in blood pressure and cardiovascular events, to the different burden in psychosocial factor and to the preserved peaceful lifestyle of the nuns2.’

Now I do not know for sure if those living in the Brazilian rain forests have managed to preserve a traditional peaceful lifestyle – but it seems a reasonable assumption to make.

However, the main point I am trying to make here is that you do not need a low salt diet in order to prevent hypertension. You can find populations with a normal salt diet who do not develop hypertension either.

What factor, or factors, appears to link these two populations? The factor appears to be living a preserved peaceful lifestyle. This would suggest that stress is the cause of hypertension and cardiovascular disease, and not salt. Whilst association cannot prove causation, a lack of association disproves it.

1: Freis ED. The role of salt in hypertension. Blood Pressure 1992; 1: 196-200.

2: Timio M, et al: ‘Blood pressure in nuns in a secluded order: A 30-year follow-up.’ Miner Electrolyte Metab. 1999 Jan-Apr;25(1-2):73-9

11 thoughts on “Salt intake – What of Nuns?

  1. Robert Kingsbury

    Can I say what a breath of fresh air it is to read your common sense and well-researched views on cholesterol, blood pressure, stress and salt intake. I’m now on my third reading of the Great Cholesterol Con and find it makes more sense every time I read it. As a non-medical 62-year-old with an apparent tendency towards arrhythmia, obesity, high cholesterol and marginally high blood pressure (although quite physically fit) I have been flagged up by my GP as prime fodder for statins, beta-blockers and a whole bucket load of pills. Encouraged by your common sense rationale, I have refused all medications. My GP has told me that, as the arrhythmia is “frequent”, I need medication. “Frequent” refers to 27 years between the two occurrences ! I’ve reached the following conclusions :
    1) If you eat a wholefood diet, there is no reason to cut out table salt anyway as you are not consuming the vast quantities of salt you get in processed food, whether it’s harmful or not.
    2) I think I’m right in saying that salt is often iodised and we need iodine. As the iodine in the soil of low-lying areas, where most of our vegetables come from (eg Lincs) has been exhausted, our iodine has to come from somewhere.
    3) I read a book many years ago (I believe by Dr Roger Birkett) in which he made a fairly simple observation that our bodies have evolved around our environment and readily available foods – fish, meat, nuts, berries, leaves, pulses etc – and if we eat those we won’t go far wrong.
    4) It’s really a comment on your stress blog – following divorce, redundancy, insolvency, business liquidation, raising four children on my own, jet-setting, working 100 hours a week and ending up with nothing but debt, I feel qualified to comment on stress. Pressure is fine but I define stress as “excessive pressure beyond our control”, whether it is physical or psychological.
    Learning to conquer stress is the most valuable lesson I have ever learnt. Sometimes, it veers out of control again with sudden traumas, but applying the principles soon brings it back under control.
    It is interesting to note that both occurrences of arrhythmia followed extreme stress. The first was after a long period of combined work and domestic stress, and the second was after a sudden trauma.
    In other words, everything you suggest as the real reasons for cardio-vascular problems seems spot on to me.
    Your thoughts and observations are worth their weight in gold to those of us who are treated as just another statistic by our GPs.

    Reply
    1. Dr. Malcolm Kendrick Post author

      Thanks for your message. Glad you are taking control of your own health. As for stress/pressure. Difficult stuff to measure, or be entirely clear about, but I do feel that there is a strong mind/body connection which has been marginalised by Western reductionist medicine.

      Reply
  2. Arie Brand

    Gary Taubes wrote an interesting review of the matter in the New York Times Sunday Review last year. He argued that the evidence for the “salt is bad” for you hypothesis has always been remarkably weak and that, in fact, there is some evidence that cutting down on salt consumption in accordance with “official” guidelines might actually be harmful. See:
    http://www.nytimes.com/2012/06/03/opinion/sunday/we-only-think-we-know-the-truth-about-salt.html?pagewanted=all&_r=0

    Reply
  3. Dennis Anthony

    It is strange that diet and other health research is not done on vast populations who exhibit ‘excessive’ life styles. For example during the analysis on smoking effects I never saw any comments on the health outcomes of most Indian women who never smoke (still true today mostly although lately more do) while their menfolk do, plus the population of Sikhs who mostly neither sex smokes – what a resource which was never used!

    As to salt there are millions who imbibe great quantities of salt namely the Tibetans. They drink yak butter (another item of dietary interest) salt tea which for most westerners is pretty distasteful, so salty and yakky(excuse the pun). Now being a Tibetan peasant and living at 12,000 feet would have to be taken into consideration but I’m sure it would be interesting to analyse their condition.

    Reply
  4. James Reeves

    I watched my father use salt liberally at every meal and eat meat fat regularly. He died in his mid 80’s, but not of heart trouble. Just a anecdotal case for sure, but I worry a lot less about salt and am in good health in my 80’s. We would all die without sodium in our diet.

    Reply
    1. Dr. Malcolm Kendrick Post author

      Sodium and potassium, these are the critical chemical elements that are needed to create many essential functions in our cells. My own belief is that excess sodium is, in reality, a lack of potassium.

      Reply
  5. Sue Fielding

    In reply to James Reeves that we would all die without sodium. Yes he’s right, but I understand that we should go mad first. Let’s get it correct :- every muscle in the body, particularly the heart, needs sodium chloride, but not singularly, it needs it with all the attendant components that are present in natural sea salt. As all salt originates from the sea it could be argued that any salt could be labelled as sea salt, but the “salt” that is sold generally in supermarkets is only sodium chloride mixed with other products to keep it free flowing. Sodium chloride singularly is poisonous. I would suggest you check out Celtic Sea Salt, I found a good unbiased article at http://www.regenerativenutrition. (I’m part way through the Great Cholesterol Con, thanks.)

    Reply
    1. Dr. Malcolm Kendrick Post author

      Sue,

      I do not believe that sodium chloride is poisonous, and I have never seen any evidence that it is. I would be happy to accept that sea salt, which contains many other substances, is probably better for our health. Speaking personally, I have seen three people who have died due to a (relative) lack of salt. I have never seen anyone – yet – who died of eating too much.

      Reply
  6. Joseph Hughes

    About four years ago after a Wellman clinic I was told I should diet and take no salt as I had high blood pressure. As it happens it was later acknowledged I had ‘white coat syndrome’ but that is as an aside.

    Back to the salt. I declined a diet sheet and devised m own, very successful, diet cutting out virtually all processed foods and took no salt in cooking food nor on the table.

    I soon found myself getting rather dizzy and even at times very nearly falling about. A friend told me I was rather reckless to do without salt as my body needed it despite many experts saying to cut back dramatically for a healthy life. I restored the cooking and table salt in mt diet and almost immediately the dizziness stopped.

    We need salt it seems.

    Reply

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