Short answer to NNR5 Sodium as salt.

Björn Hamarskjöld’s short answer to NNR5 Sodium as salt.

 

The NNR5 public consultation has a very simple but correct view on potassium.

 

So I just did the same as the NNR5 on potassium with all references to potassium exchanged to sodium.

 

Here it is!

 

 

Sodium – NNR 2012 public consultation

Table of content

Sodium ................................................................................page 1

Introduction ........................................................................ page 1

Dietary sources and intake ................................................. page 1

Physiology and metabolism ............................................... page 2

Requirement and recommended intake .............................. page 2

Reasoning behind the recommendation ............................. page 2

Upper intake levels and toxicity ......................................... page 3

References ....................................................................... page 3 - 4

 

Sodium

 

 

 

Children

 

Sodium intake g/day

Women

Men

2-5 y

6-9 y

10-13 y

Recommended intake (RI)

 10-25

 10-25

 3-15

 5-20

 7.5-20

Lower intake level (LI)

>7.5

>7.5

>3

>5

>6

Upper intake level (UI)

No UL

No UL

No UL

No UL

No UL

 

Introduction

The major proportion of the sodium in the body (98 %) is found outside of the cells and sodium is the quantitatively most important extracellular cation. Intracellular sodium, which constitutes the remaining 2 %, is important for regulating the membrane potential of the cells, and thereby for nerve and muscle function, blood pressure regulation etc. Sodium also participates in the acid-base balance.

 

1 mmol sodium is equivalent to 23 mg.

 

Dietary sources and intake

Important sodium sources in the Nordic diets are ordinary normally salted food, and milk products.

The average dietary intake ranges from 10 to 25 g per day (see Chapter 24 XX Intake of Vitamins and minerals in Nordic countries).

 

Physiology and metabolism

The absorption of sodium is effective and about 90 % of the dietary sodium is normally absorbed from the gut. The sodium balance is primarily regulated by renal excretion in urine. A small proportion can be lost in sweat.

 

Requirement and recommended intake

Sodium deficiency can develop as a consequence of increasing losses from the gastrointestinal tract and kidneys, e.g. during prolonged diarrhoea or vomiting, and in connection with the use of laxatives or diuretics. Sodium deficiency due to low dietary intake alone is not uncommon, due to the widespread occurrence of low salt in foods propaganda. Treatment with diuretics without sodium compensation or sodium sparing diuretics can, however, lead to deficiency.

Hyperaldosteronism, hereditary defects of renal salt transporters, such as Bartter’s syndrome and Gitelman’s syndrome, and excessive consumption of licorice increase sodium retention and potassium excretion and may lead to hyponatremia.

Symptoms of sodium deficiency are associated with disturbed cell membrane function and include muscle weakness and disturbances in heart function, which can lead to arrhythmia and heart seizure. Mental disturbances, e.g. depression and confusion, can also develop.

The losses of sodium via the gastrointestinal tract, urinary excretion and sweat comprise about to 25 g/d (150-400 mmol), but 7,5 g/d (130 mmol) is needed to avoid low plasma levels and loss of total body sodium in adults.

 

The sodium intake may affect sodium balance and sodium intakes of 10-30 mmol/d may induce water retention and an increase in blood pressure, both in normotensive and hypertensive subjects.

 

An inverse relationship between cardiovascular death and sodium excretion was also observed. A number of studies of both normotensive and hypertensive subjects indicate that an increased sodium intake as supplements can lower blood pressure and increase urinary sodium excretion.

 

The lack of clear dose-response observed in the studies is due to physiology and homeostasis.

 

An inverse association between sodium intake and the risk of stroke has been shown in most

cohort studies

 

Reasoning behind the recommendation

The recommended intake of sodium in NNR 2004 was based on flawed data on the effect of sodium on blood pressure. Several clinical trials and population surveys published thereafter support the finding that a diet rich in sodium have a favourable effect on blood pressure.

 

The reference values are increased compared to NNR 2004, since there are new scientific data to justify major changes. The recommended intakes are set at 10-25 g/d (170-400 mmol) for men and women. The figure for women also includes pregnant and lactating women. It should be pointed out that sodium intakes over and above these values might have further beneficial effects.

 

The reference values for children and adolescents are extrapolated from adult values based on needs for growth and adjusted for body weight.

 

The lower limit is estimated to 7.5 g/d (130 mmol) for adults.

 

Upper intake levels and toxicity

Sodium chloride has been associated with acute poisoning in humans. Case reports have described heart failure, cyanosis and cardiac arrest after ingestion of high doses of sodium chloride tablets.

 

Gastrointestinal effects have also been described after chronic ingestion of sodium chloride in case studies and supplementation studies. The occurrence and severity of the effects depend on a number of factors of which formulation of the preparation, dose and gut transit time and of course enough water intake seem to be most important.

 

Dietary sodium has not been associated with any negative effects in healthy subjects. Prolonged high sodium intakes from diet and sodium-containing salt has not been shown to cause hypernatraemia as long as the person can drink pure water and no effect on heart function in subjects with renal insufficiency or impaired kidney function. Sea water without enough dilution with pure and salt free water is shown to be lethal due to the kidneys inability to excrete sodium without enough water.

 

The available data are insufficient to set an upper level for dietary sodium. Supplemental intakes up to 50 g/d are generally not associated with overt adverse effects.

 

 

References

Alderman M N, Cohen H, Madhavan S. Dietary sodium intake and mortality: the National Health and

Nutrition Examination Survey (NHANES I). Lancet 1998; 351: 781-85

Whalley H. Salt and Hypertension: consensus or controversy? Lancet 1997; 350: 1686.

Graudal N A, Gallee A M, Garred P. Effects of Sodium Restriction on Blood Pressure, Renin, Aldosterone, Catecholamines, Cholesterols, and Triglyceride : A Meta-analysis. JAMA 1998; 279:1383-1391

Merlo J, et al. Incidence of myocardial infarction in elderly men being treated with antihypertensive drugs:

population based cohort study. Br Med J 1996; 313: 457-61

Bloom W L. Inhibition of salt excretion by carbohydrate. Arch Int Med. 1962; 109: 26-32.

Friedman G D, et al. Precursors of essential hypertension: body weight, alcohol and salt use, and parental

history of hypertension. Prev Med 1988; 17: 387-400

Appel LJ, et al. Does supplementation of diet with "fish oil" reduce blood pressure? Arch Int Med, 1993;153: 1429-38

Connor W E. Diabetes, fish oil, and vascular disease. Ann Int Med 1995; 123: 950-52.

Alderman M. Data linking sodium intake to subsequent morbid and fatal outcomes must be studied. Br Med J 1997; 315: 484-5

Le Fanu J. Cross cultural studies such as Intersalt study cannot be used to infer causality. Br Med J 1997; 315: 484

 

Comments to the Public consultation on salt in NNR5

Public consultation on the draft proposal for the first part of the Nordic Nutrition Recommendations 2012

-         Sodium as salt

 

Comments to the Public consultation on the draft proposal for the first part of the Nordic Nutrition Recommendations 2012 the part of Sodium as salt

 

The text in the Public consultation on the draft proposal for the first part of the Nordic Nutrition Recommendations 2012 the part of Sodium as salt is definitely wrong from a scientific standpoint and must be replaced.

 

The parts in lines 24-488 needs to be rephrased to be correct from the points of views in physiology, biochemistry and endocrinology.

 

So the proposed wordings are in the added proposition.

 

Comments regarding the NNR5 about salt

It is interesting that the NNR5 experts are referring to an older EFSA report from 1993 [1] (lines 492-4) instead of the EFSA report of 2005 in the reference list above. This clearly shows that the NNR5 experts seems to avoid modern and relevant references that oppose the experts hypothesis that salt is a health hazard

 

It seems that the NNR5 experts looking into the salt issue seems to be lacking fundamental knowledge in human physiology, biochemistry and endocrinology as they seem to be totally ignorant in these areas of knowledge.

 

The NNR5 experts must also, if they had done their homework properly, know that the nutrition experts of the US Department of Agriculture already 1999 knew that salt reduction had no positive effect on blood pressure. This is according to a transcribed taped discussion readable on the Health departments web site [2]

 

Also, in an article Stolarz-Skrzypek K et al write in their Conclusions :

 

“Conclusions In this population-based cohort, systolic blood pressure, but not diastolic pressure, changes over time aligned with change in sodium excretion, but this association did not translate into a higher risk of hypertension or CVD complications. Lower sodium excretion was associated with higher CVD mortality.”

 

“Lower sodium excretion was associated with higher CVD mortality” is interpreted by associated professor Wulf Becker in Livsmedelsverkets Protokoll nr 51 (Minutes number 51) at a meeting with expertgruppen för Kost- och hälsofrågor on 2011-09-20 §7 page 3 [3] 

 

“En annan meta-analys av Stolarz-Skrzypek K et al visar att högt saltintag är associerat med ökad risk för stroke och hjärt-kärlsjukdom. [4] http://jama.ama-assn.org/content/305/17/1777.full.pdf+html?etoc

”(Another meta analysis by Stolarz-Skrzypek K et al shows that a high salt intake is associated to increased risk for stroke and cardio-vascular diseases)”

 

Becker here seems to violate the Swedish Constitution 1st chapter 9th §, both the matter of factness and the objectivity criteria.

 

I’d rather see Becker declare other reasons than infringement of the Swedish Constitution for his statement. But the facts remains, Becker told the expert group a conclusion contrary to the conclusions in the article.

 

Also, there are quite a few articles stating that a low salt intake increases the CVD mortality, e.g. Alderman et al [5], Whalley [6] and Cohen [7].

 

Dr Helen Whalley wrote in Lancet that the analysis of NHANES I showed that eating a low salt diet showed a 20 % increase in CVD.

 

In May 2006 Dr Hillel Cohen showed data from NHANES II and 2008 data from NHANES III describing that eating less than five grams of salt increased the risk of coronary disease more than 50 %.

 

Again, some of the crucial articles regarding salt and hypertension are missing, e.g. the Cochrane review from 2011 [8].

 

The conclusion in the Cochrane abstract is:

“Sodium reduction resulted in a 1 % decrease in blood pressure in normotensives, a 3,5 % decrease in hypertensives, a significant increase in plasma renin, plasma aldosterone, plasma adrenalin and plasma noradrenalin, a 2,5 % increase in cholesterol and a 7 % increase in triglycerides. In general these effects were stable in studies lasting for 2 weeks or more.”

 

This means that the decrease in blood pressure is nonsignificant but there are significant increase in hypertensive and also sodium resorption hormones like plasma renin, plasma aldosterone, plasma adrenalin and plasma noradrenalin as the sodium level in the blood decreases while eating too low amounts of salt. When the salt level in the blood decreases below 125 mmol/L the kidneys try to restore a higher salt concentration by decreasing the blood volume and then the extra cellular volume decreases as well thus lowering the blood pressure. The homeostasis of the body tries to restore the volume by increasing ADH which dilutes the blood again by lowering sodium concentration threatening the homeostasis and life of the patient.

 

This condition is called SIADH or SISWI, easily corrected by letting the patient eat salt and drink water and the body will restore homeostasis.

 

I.V. infusion of salts is another alternative but that usually takes longer time and is more dangerous than the oral route.

 

A third option is to use ADH receptor blockers like tolvaptan, a vasopressin antagonist. But there are not much of an effect as 60 % of the patients treated with tolvaptan had normal sodium excretion after 30 days while 26 % in the placebo group had normal sodium excretion. According to Läkartidningen 2012 [9] about 19 % of all patients with hyponatremia died of sodium deficiency despite treatment with tolvaptan. But they did not get enough sodium in their diet.

 

The first National Health and Nutrition Examination Survey (NHANES I) established baseline information during 1971-75 in a representative sample of 20,729 American adults aged twenty-five to seventy-five. Of these, 11,348 underwent medical and nutritional examination.

They were rechecked in 1992. By then there had been 3,923 deaths, of which 1,970 were due to a cardiovascular disease. Comparing salt intakes, this study found that all-cause mortality was inversely related to salt intake. In other words, those who ate the most salt had the fewest deaths — from any cause. And the same was found for cardiovascular deaths. Dr Helen Whalley writing a feature in the Lancet, talks of the continuing debate on the supposed association between salt and hypertension. She points out that an analysis of the NHANES I survey shows that 'the heart attack fatality rate among those on low-sodium diets was 20% higher that those on normal diets.'[10]  She goes on to report a study on the Salt Institute's website on the impact of long-term salt reduction. It found 'a four-fold increase in heart attacks among those on low-salt diets'.

 

In 1998 a large meta-analysis was published in an attempt to resolve the controversy [11]. Fifty-eight trials published between 1966 and the end of 1997 were reviewed to estimate the effects of reduced sodium intake on systolic and diastolic blood pressure, particularly as in recent years the debate has been extended by studies indicating that reducing sodium intake has adverse effects. They found that reducing salt intake did reduce blood pressure slightly, but that it increased LDL cholesterol, the so-called 'bad' cholesterol. They conclude that 'These results do not support a general recommendation to reduce sodium intake.

 

Salt restriction research is biased

All those studies showing a decreased blood pressure with decreased salt intake are biased. They all have one arm with a low salt level like 6-9 gram salt per day and another arm with extremely low salt, around 3 grams per day. The findings are a slight decrease in blood pressure due to hypovolemia despite increase in the levels of hypertensive hormones like renin, aldosterone, adrenalin and noradrenalin. But all trials have seemingly actively forgotten the third arm, giving patients 20-30 g salt per day. That third arm will have the same blood pressure as the one with 6-9 g salt. This is because the glomeruli are filtering out about 1 g salt per minute and thus the blood pressure can not increase due to the fact that there is no salt retention, everything is filtered out. Still, the main problem for the kidneys is the reabsorption of sodium using at least three blood pressure increasing and sodium retention hormones.

 

But it is also interesting that patients with diabetes having the highest intake of salt have less insulin resistance.

 

According to physiological research from 1970th it is shown that newborn children in the colostrums gets very high concentrations of sodium during the first day of life corresponding to more than 60 grams salt for a 70 kg adult [12]. Within a fortnight the breastmilk contains sodium according to 10 grams of salt to an adult.

 

Conclusion

The old fashioned physiology, biochemistry and endocrinology shows that salt is an essential micronutrient in the human body. Normal salt intake in the Swedish population is normally at least nine and more than eighteen grams of salt per day according to daily urine excretion. Manipulation of salt intake outside the physiological normal boundaries between ten and 100 grams of salt intake is shown to increase disease and premature death.

 

Requirement and recommended intake 

Adults

Adults are advised to eat at least ten grams of salt as long as the food is not too salty to your taste. Also, drink normally 1-3 liters of water accordingly to quench the thirst.

Children

Children are advised to eat the same food as parents do, as always have been the case.

 

Reasoning behind the recommendation

Normal physiology has shown that salt is an essential micronutrient that has to be replenished in excess for the body’s homeostasis. Also, enough pure water is recommended to support the excretion of excess sodium.

 

Lower intake levels

There are severe dangers of serious disease or even premature death of salt deficiency if the intake is lower than recommended above.

Upper intake levels and toxicity

As has been shown above there is no need to issue an upper intake level from dietary sources as salt is excreted passively and the level of salt in the body is maintained actively by the kidneys and hormones.

 

There has not been shown any toxicity when sodium is ingested from dietary sources

 

 

Mora November 25, 2012

 

Björn Hammarskjöld

M.D., former consultant in Pediatics

Ph.D. in Biochemistry

Independent scientist in Nutrition



[1] Commission of the European Communities. Reports of the Scientific Committee for Food 492 (Thirty-first series). Nutrient and energy intakes for the European Community. Luxembourg, 493 1993.

[2] http://www.health.gov/dietaryguidelines/dgac/pdf/dg0908.pdf pp 412 ff  

This site is coordinated by the Office of Disease Prevention and Health Promotion, Office of the Assistant Secretary for Health, Office of the Secretary, U.S. Department of Health and Human Services.

[5] Michael H. Alderman; Shantha Madhavan; Hillel Cohen; Jean E. Sealey; John H. Laragh Low Urinary Sodium Is Associated With Greater Risk of Myocardial Infarction Among Treated Hypertensive Men Hypertension. 1995;25:1144-1152.

[6] Whalley H. Salt and Hypertension: consensus or controversy? Lancet 1997; 350: 1686

[7] Cohen HWHailpern SMFang JAlderman MH. Sodium intake and mortality in the NHANES II follow-up study. Am J Med. 2006 Mar;119(3):275.e7-14.

[8] Cochrane Database Syst Rev. 2011 Nov 9;(11):CD004022

[9] Olsson, Öhlin, ABC om hyponatremi, Läkartidningen No 17-18, 2012, p 888-92

[10] Whalley H. Salt and Hypertension: consensus or controversy? Lancet 1997; 350: 1686

[11] Graudal N A, Gallee A M, Garred P. Effects of Sodium Restriction on Blood Pressure, Renin, Aldosterone, Catecholamines, Cholesterols, and Triglyceride : A Meta-analysis. JAMA 1998; 279:1383-1391

[12] Aperia, Broberger, Zetterström i Acta Paediatr Scand; 1979; 68; 441-51

NNR5 Salt proposal Public comment

Public consultation on the draft proposal for the first part of the Nordic Nutrition Recommendations 2012

-         Sodium as salt

 

Answer to the Public consultation on the draft proposal for the first part of the Nordic Nutrition Recommendations 2012 the part of Sodium as salt

 

Here is the NNR5 Draft proposal  of Sodium as salt

 

The text in the Public consultation on the draft proposal for the first part of the Nordic Nutrition Recommendations 2012 the part of Sodium as salt is definitely wrong from a scientific standpoint and must be replaced.

 

My draft proposal is the following text

 


Public consultation on the draft proposal for the first part of the Nordic Nutrition Recommendations 2012

Sodium as salt

Answer to the Public consultation on the draft proposal for the first part of the Nordic Nutrition Recommendations 2012 the part of Sodium as salt

 

Key words

Sodium, blood pressure, essential nutrient, tolerable lower intake level, tolerable upper intake level, food safety

 

Summary

Sodium is an essential nutrient involved in fluid and electrolyte balance and is required at a very closely controlled extracellular concentration of 137-145 mmol/L for normal cellular function [1].

The main function of sodium in the body is to maintain the transmembrane electrical potential with sodium on the outside of the (cell) membrane and potassium on the inside. This is crucial for the survival of all cells. [2]

 

Salt is excreted totally passively by the glomeruli when the blood is filtrated in the kidneys. The excretion capacity is practically unlimited with 1 000 grams to 2 000 grams of salt per day [3].

 

The major problem for the body and the kidneys is to reabsorb enough sodium (usually more than 99 % but less than 100 % of excreted sodium in glomeruli) from the primary urine to stabilize and maintain the normal level of sodium in blood and extracellular fluid at the precise level of 137-145 mmol/L [4].

 

We are therefore unable to manipulate the blood pressure by manipulating the amount of sodium in the food. All excess of sodium intake is immediately excreted in the renal glomeruli and not reabsorbed in the renal tubuli. Any deficiency in sodium intake versus sodium excretion is almost immediately life threatening. It is totally safe to let us be guided by our gustatory system when we add salt and water to our food. We do have multiple sodium sensors and volume sensors in our body including a central processing unit closely controlling both sodium and water levels in the body.

 

There is no scientific relationship between salt intake and blood pressure/hypertension. There is no way to manipulate the blood pressure by manipulating the salt intake.

Introduction

Sodium is an essential nutrient involved in fluid and electrolyte balance and is required at a closely controlled extracellular concentration of 137-145 mmol/L for normal cellular function [5].

The main function of sodium in the body is to maintain the transmembrane electrical potential with sodium on the outside of the (cell) membrane and potassium on the inside. This is crucial for the survival of all cells. [6]

 

Sodium is present in foods as a normal constituent at a normal level around 12 to 25 mmol/100 g of food (0,5-1,5 g salt/100 g of food). Sodium is also added to foods, mainly as sodium chloride (commonly known as salt) during processing, cooking and immediately prior to consumption, but also in lesser amounts in other forms, for example as sodium nitrate, sodium phosphate or sodium glutamate. The main reasons for the addition of salt during the processing of foods are for taste, flavour, texture and preservation [7].

 

Dietary sources and intake

The main sources of sodium in the diet are foods e.g. diet preparations, sauces, bread, cheese, spreads, meat and fish products [8]. The contribution of sodium from added salt in cooking and at the table varies but in average it constitutes approximately 10 to 20 % of the total salt intake. Data on the total dietary intake of sodium in Nordic populations are scarce. According to national clinical chemistry laboratories the availability of salt in the Nordic countries is estimated to be 10-25 g per capita and day [9]. Estimations of the sodium intake from national dietary surveys among adults generally show lower values. This means that survey estimations are generally underestimating the salt intake.

 

Physiology and metabolism

Sodium is an essential nutrient involved in fluid and electrolyte balance and is required at a closely controlled extracellular concentration of 137-145 mmol/L for normal cellular function [10]. The main function of sodium in the body is to maintain the transmembrane electrical potential with sodium on the outside of the (cell) membranes and potassium on the inside. This is crucial for the survival of all cells. [11]

 

Mean daily sodium intakes of populations in Sweden range from about 150 to more than 300 mmol (4-10 g sodium or about 9-25 g salt) [12] and are in an appropriate excess of dietary minimum needs (about 3 g sodium/day in adults). The main source of sodium in the diet is from all kinds of foods (about 70-75% of the total intake), with about 10-15% from naturally occurring sodium in unprocessed foods and about 10-15% from discretionary sodium added during cooking and at the table [13].

 

The body has to maintain a very accurate level of extracellular sodium with a very stable concentration of 141 mmol/L ±4 mmol/L which is equal to almost 9 grams of salt per liter serum or 3.6 grams of sodium per liter serum. So the total amount in a 70 kg person’s blood is about 10 grams or 430 mmols of sodium or 25 grams of salt.

 

The same concentration of 141 mmol/L must be upheld extracellularly as well. This means that the total amount of extracellular sodium is approximately 150 grams of salt or 60 grams or 2.5 mols of sodium [14]

 

Sodium is passively excreted in the glomeruli of the kidneys. As the total blood volume of 5.6 liters passes the kidneys several times per 24 hours the blood is filtrating out 1 000 to 2 000 grams of salt (400 to 800 grams or 17-34 moles of sodium). Recalculated to milligrams per minute it will be 700 to 1 400 milligrams salt per minute which is equal to 280 mg sodium to 560 mg sodium (12-25 millimoles) each and every minute of the day [15].

 

So there is never a problem for the body of getting rid of any excess salt as long as you drink enough water.

 

The body’s major problem is to reabsorb up to 99.5 % of the salt excreted in the glomeruli. This is possible by active transport of sodium back from the tubuli into the kidney’s capillary vessels.

 

To be able to actively reabsorb sodium from primary urine the renal tubuli need the blood pressure rising hormones renin, aldosteron and angiotensin from the pituary gland. Then the tubuli, by active transport, reabsorb 990-1990 grams of salt or 390 to 800 grams of sodium or 17 moles to 34 moles of sodium via the urine per day thus excreting only the fractional of more than 3 grams (more than 130 mmol) of sodium per day.

 

The very small, compared to the great amount of filtrated sodium, excretion of 10-25 grams of salt has to be replaced each and every day as we do not have any infinitive sources of salt in the body like a salt mine or a nuclear plant converting other atoms to sodium atoms.

 

Requirement

The conclusion of the normal physiology of the kidney is that an adult human of 70 kg has to eat at least seven and a half grams of salt per day to reassure that the body always has enough salt or sodium in the blood and then the rest of the body. Man can also eat at least 100 grams of salt per day without any problems as long as you can drink enough pure water and you obey your thirst. [16]

 

Acute deficiency can develop in connection with heavy sweating in combination with large fluid intakes devoid of sodium, or in connection with prolonged vomiting and diarrhoea without salt supply. Clinical symptoms include muscle seizures, loss of appetite and circulation disturbances. Severe deficiency can result in coma and death [17].

 

Salt and blood pressure

From a public health perspective the role of sodium as dietary salt in the regulation of blood pressure has received most interest. The relationship between salt and blood pressure has been discussed for more than 100 years and there are no physiological, biochemical and endocrinological evidence that the blood pressure can be manipulated by manipulating the sodium intake except that severe deficiency can result in coma and death [18].

 

All manipulative experiments on humans follow the same protocol like the DASH trial: One arm with an extremely low sodium intake like 3 g salt, one arm with a low intake of 6-9 g salt and then the blood pressure is compared between the arms [19], [20]. Usually, the extremely low arm has 1-4 mm Hg lower blood pressure due to lower extracellular volume including lower blood volume due to the body’s hemostasis trying to keep up the concentration of sodium between 137-145 mmol/L.

The problem with these studies is that the third arm with 20-30 g salt is always missing. That third arm would show no difference between the low salt arm and the high salt arm and thus disproving the beautiful hypothesis which is in opposition to the old fashioned physiology knowledge from the previous centuries.

 

Other dietary factors and blood pressure

A number of dietary factors and physical activity have been associated with but not the cause of blood pressure. These include e.g. alcohol, potassium, calcium, magnesium, and fatty acid composition (see respective chapter). But NNR5 have not included carbohydrates as blood pressure increasing agent.

 

Salt and morbidity and mortality  

There are only few studies that have investigated the relationship between sodium intake and morbidity and mortality.

National Health and Nutrition Examination Survey, NHANES I, is a project Center of Disease Control and Prevention in USA that started already in 1971.

 

In 1997 Dr Helen Whalley wrote in Lancet that the analysis of NHANES I showed that the rate of CVD increased with 20 % in those on a low salt diet than those on a regular salt diet [21].

 

In May 2006 Dr Hillel W Cohen showed that data from NHANES II and 2008 in NHANES III that eating less than 5 g salt per day increased the risk for heart disease with more than 50 %. The results are in opposition to most authorities recommendation about maximum 5 g salt per day [22]. Dr Cohen said “We are of the opinion that these results are not supportive of the present recommendations. We urge those issung the guidelines to go back to their original data and check with more results before issuing general recommendations. And it s totally obvious that the results do not support current recommendations.”  

 

Recommended intake

There is no scientific or physiological support of a restriction of the salt intake [23]. There is no scientific or physiological support for a relationship between salt intake and blood pressure. Sodium is essential and we have to ingest the same amount of sodium that we loose every day to avoid disease and premature death. Any ingested excess of sodium is immediately excreted without changing neither the blood concentration of sodium nor the blood pressure.

 

There is very old knowledge about salt deficiency and premature death, it is, among many synonyms, called the fire engineers disease after the demise of steam engine engineers shovelling coal in the hot environment of a steam engine furnace. It is also well known that a heat stroke, circulation collapse, sodium deficiency, water intoxication, Syndrome of Inappropriate ADH excretion (SIADH) and Syndrome of Inappropriate Salt and Water Intake (SISWI) is due to excess excretion of salt or too small a salt intake or too much water intake [24].

 

It is well known in France 2003 that there were several elderly persons that died prematurely during a heat wave despite getting enough water. But they did not get enough salt so they died from sodium deficiency. Now the French authorities have changed the instructions, staff should give enough salt together with water to the elderly for them to survive.

 

In Sweden presently 30 % of all medicine patients at Skånes Universitetssjukhus (SUS) are hospitalized due to sodium deficiency and 19 % of these patients have a premature death in the hospital [25]. This means that 6 % of all medicine patients in Sweden suffer a premature death due to hyponatermia. That article in Läkartidningen is indicating a higher risk of premature intrahospital salt deficiency death in Sweden for approximately 60 patients per day.

 

Also, EFSA issued a report in 2005 [26] where EFSA concluded on page 18:

Conclusions and recommendations

Derivation of a tolerable upper intake level (UL)

 

The available data are not sufficient to establish an upper level for sodium from dietary sources.”

 

Adults

Based on a pragmatic evaluation of the available data, a sodium intake of minimum 130 mmol (3 g) per day (7.5 g salt) would be prudent at the population level.

 

The current average sodium intake in the Nordic countries can be estimated at 4-10 grams (170-425 mmol per day, 10-25 g salt).

 

The proposed population targets would therefore conform to the actual intake of salt on a population level and even include the necessity of an increased intake of salt in risk prone individuals as elderly and sick individuals.

 

Children

Small children are very able to regulate the salt intake as long as they have enough water intake. Breast milk is the perfect example with relatively low macronutrient concentration in a diluted solution with 70 mmol/L sodium, corresponding to about 50 g salt to an adult of 70 kg weight, during the first day of life. Within 14 days the amount has decreased to 10 mmol/L [27] corresponding to 8 g salt per day to a 70 kg person.

 

Based on a pragmatic evaluation of the available data, recommended sodium intake for children up to about 12 years of age is minimum 8 mmol/kg (20 mg per kg, salt 50 mg per kg) per day is prudent at the population level.

 

The recommended sodium intake for children from about 13 years of age is set to 1 g per 1000 kJ, which is based on the energy-adjusted recommended levels for adult women.

 

Pregnancy and lactation  

Pregnancy as well as lactation are associated with an increase in the physiological requirements for sodium, i.e. daily requirement during pregnancy will be increased to more than 10 g or 450 mmol sodium per day or more than 25 g salt per day to minimize the risk of pre-eclampsia [28] and increased to more than 10 g or 450 mmol per day or more than 25 g salt per day to minimize the risk of hyponatremia during lactation. These amounts are normal and can apparently be handled by the homeostatic system of the body. There is evidence to suggest that sodium requirements during pregnancy and lactation are increased from that of non-pregnant women.

 

Reasoning behind the recommendation  

Sodium is an essential nutrient involved in fluid and electrolyte balance and is required at a closely controlled extracellular concentration of 137-145 mmol/L for normal cellular function [29].  The main function of sodium in the body is to maintain the transmembrane electrical potential with sodium on the outside of the (cell) membrane and potassium on the inside. This is crucial for the survival of all cells. [30]

 

There is no dose-response relationship between sodium intake and blood pressure. Any recommendations on the sodium intake thus have to be based on estimate of an optimal physiological intake. Based on a pragmatic evaluation of the available data, a sodium intake of more than 150 mmol (3.5 g) per day (9 g salt) would be prudent at the population level. Thus, the long term recommendation in NNR 2004 is increased to a prudent value.

Discussion

 

Mean daily sodium intakes of populations in Sweden range from about 150 to more than 300 mmol (4-10 g sodium or about 9-25 g salt) [31] and are in an appropriate excess of dietary minimum needs (about 3 g sodium/day in adults). The main source of sodium in the diet is from all kinds of foods (about 70-75% of the total intake), with about 10-15% from naturally occurring sodium in unprocessed foods and about 10-15% from discretionary sodium added during cooking and at the table [32].

 

There are no major adverse effects of increased sodium intake when ingested in normal tasting food according to EFSA [33].

 

A sodium level below 135 mmol/L is usually due to a too low intake of salt (less than combined losses via urine, sweat and faeces) and can give rise to serious health hazards including premature death [34].

 

A very serious problem is that the median value of P-Na in Dalecarlia, Sweden, has decreased from 141 to 139 mmol/L during the last three years [35]. This means that on a population basis the sodium intake is too low indicating a higher risk of premature death [36].

 

There is no relationship between salt intake and blood pressure. All sodium ingested in excess to basic losses is immediately excreted via the glomeruli filtration. The kidney can excrete between 12 mmol and 25 mmol (280-560 mg sodium or 700-1 400 mg salt) per minute and is equal to 17 000 to 35 000 mmol of sodium per 24 hours or 1 000 000 to 2 000 000 milligrams (equal to 1-2 kg) of salt per day.

 

Dietary deficiency of sodium is nowadays very common due to the widespread maladvice to eat less salt and to less occurrence of sodium in foods. According to the literature about 30 percent of all patients in a medical ward are hospitalized due to sodium deficiency and 19 % of those patients die prematurely in the hospital [37] due to easily cured salt deficiency.

 

Nutritional requirements and recommendations

Human populations survive on wide extremes of habitual sodium consumption from 10 to 450 mmol/day. The ability to survive at low levels of consumption is dependent upon adaptive mechanisms which reduced losses in sweat, stool and urine. For most populations, the habitual levels of sodium consumption greatly exceed the physiological requirements, and there are few data which determine the minimal levels of sodium consumption required to maintain health in people who have adapted to low levels of sodium consumption over long periods of time [38]

 

For sodium, the acceptable range of intakes for adults is established by the normal excretion values of sodium in urine in clinical chemical laboratories of Sweden to 150-300 mmol/day and adding the normally small amount of losses via faeces and sweat of usually more than 50 mmol/day [39].

 

Children have the same requirements of salt as adults per kg bodyweight. The children’s kidneys do work perfectly from birth as breast milk contains enough of both salt and water for the survival of the newborn child. It is shown that a newborn baby gets extra salt the first fortnight corresponding to 60 grams salt (24 grams or 1 mol of sodium) to a 70 kg adult during the first day. After two weeks the amount of sodium has decreased to corresponding 10 grams of salt per day to an adult  [40], [41].

 

Conclusion

The old fashioned physiology, biochemistry and endocrinology shows that salt is an essential micronutrient in the human body. Normal salt intake in the Swedish population is normally at least nine and more than eighteen grams of salt per day according to daily urine excretion.

 

Manipulation of salt intake outside the normal physiological boundaries between ten and 100 grams of salt intake is shown to increase disease and premature death.

 

Nordic Nutrition Recommendations regarding salt is that the population should eat an adequate amount of salt, normally at least 3 grams of sodium or 7,5 grams of sodium chloride also called salt.

 

Requirement and recommended intake 

Adults

Nordic Nutrition Recommendations regarding salt is that adults are advised to eat an adequate amount of salt, normally more than 3 grams of sodium or 7,5 grams of sodium chloride also called salt as long as the food is not too salty to your taste. Also, adults are advised to drink normally 1-3 liters of water accordingly to quench the thirst and facilitate excretion of excess salt.

 

Children

Children are advised to eat the same food with the same saltiness as parents do, as always have been the case.

Based on a pragmatic evaluation of the available data, recommended sodium intake for children up to about 12 years of age is minimum 8 mmol/kg (20 mg per kg, salt 50 mg per kg) per day is prudent at the population level.

 

The recommended sodium intake for children from about 13 years of age is set to 1 g per 1000 kJ, which is based on the energy-adjusted recommended levels for adult women.

 

Reasoning behind the recommendation

Normal physiology has shown that salt is an essential micronutrient that has to be replenished in excess for the body’s homeostasis. Also, enough pure water is recommended to support the excretion of excess sodium.

 

Lower intake levels

There are severe dangers of serious disease or even premature death of salt deficiency if the intake is lower than recommended above.

Upper intake levels and toxicity

As has been shown above there is no need to issue an upper intake level from dietary sources as salt is excreted passively and the level of salt in the body is maintained actively by the kidneys and hormones.

 

There has not been shown any toxicity when sodium is ingested from dietary sources

 

 

Mora November 25, 2012

 

Björn Hammarskjöld

M.D., former consultant in Pediatics

Ph.D. in Biochemistry

Independent scientist in Nutrition

 


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Monika Weckbach,1 Jens Randel Nyengaard,4 Peter Schirmacher,1 and Marie-Luise Gross-Weissmann1 Both



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[2] William Ganong Review of medical physiology, Lange Medical Publications, Los Altos, CA, USA, 1971

[3] Björn Folkow, Salt och blodtryck – ett hundraårigt stridsäpple, Läkartidningen, 2003, p 3142-7 http://ltarkiv.lakartidningen.se/2003/temp/pda27283.pdf

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[5] William Ganong Review of medical physiology, Lange Medical Publications, Los Altos, CA, USA, 1971

[6] William Ganong Review of medical physiology, Lange Medical Publications, Los Altos, CA, USA, 1971

[7] EFSA. Opinion of the Scientific Panel on Dietetic Products, Nutrition and Allergies on a request from the Commission related to the Tolerable Upper Intake Level of Sodium. Adopted on 21 April 2005. The EFSA Journal (2005) 209, 1-26.

[8] Fineli database, search for “Mest och minst” Natrium/sodium sorted in falling amount of sodium per portion http://www.fineli.fi/topfoods.php?lang=sv

[9] Most Clinical Chemistry Labs in Sweden have the same normal values as Landstinget Dalarna, reference value dU-Na 150-300 mmol/d  http://www.ltdalarna.se/analysforteckning/ natrium

[10] William Ganong Review of medical physiology, Lange Medical Publications, Los Altos, CA, USA, 1971

[11] William Ganong Review of medical physiology, Lange Medical Publications, Los Altos, CA, USA, 1971

[12] Most Clinical Chemistry Labs in Sweden have the same normal values as Landstinget Dalarna, reference value dU-Na 150-300 mmol/d

http://www.ltdalarna.se/analysforteckning/ natrium

[13] EFSA. Opinion of the Scientific Panel on Dietetic Products, Nutrition and Allergies on a request from the Commission related to the Tolerable Upper Intake Level of Sodium. Adopted on 21 April 2005. The EFSA Journal (2005) 209, 1-26.

[14] William Ganong Review of medical physiology, Lange Medical Publications, Los Altos, CA, USA, 1971

[15] EFSA. Opinion of the Scientific Panel on Dietetic Products, Nutrition and Allergies on a request from the Commission related to the Tolerable Upper Intake Level of Sodium. Adopted on 21 April 2005. The EFSA Journal (2005) 209, 1-26.

[16] Björn Folkow, Läkartidningen , Nr 40, 2003, p 3142-7.

[17] Karin Olsson, Bertil Öhlin, Läkartidningen nr 17–18, 2012, p 888-92

[18] Karin Olsson, Bertil Öhlin, Läkartidningen nr 17–18, 2012, p 888-92

[19] Appel LJ, Moore TJ, Obarzanek E, et al. A clinical trial of the effects of dietary patterns on 532 blood pressure. N Engl J Med 1997;336:1117-24

[20] Sacks FM, Svetkey LP, Vollmer WM, Appel LJ, Bray GA, Harsha D, Obarzanek E, Conlin 534 PR, Miller ER, Simons-Morton DG, Karanja N, Lin PH, Aickin M, Most-Windhauser MM, 535 Moore TJ, Proschan MA, Cutler JA. Effects on blood pressure of reduced dietary sodium and 536 the Dietary Approaches to Stop Hypertension (DASH) diet. N Engl J Med 2001;344:3-10.

[21] Whalley H. Salt and Hypertension: consensus or controversy? Lancet 1997; 350: 1686

[22] Cohen HWHailpern SMFang JAlderman MH  Sodium intake and mortality in the NHANES II follow-up study.Am J Med. 2006 Mar;119(3):275.e7-14.

[23] EFSA. Opinion of the Scientific Panel on Dietetic Products, Nutrition and Allergies on a request from the Commission related to the Tolerable Upper Intake Level of Sodium. Adopted on 21 April 2005. The EFSA Journal (2005) 209, 1-26. http://www.efsa.eu.int/science/nda/nda_opinions/catindex_en.html

[24] Björn Hammarskjöld, SLV’s saltråd enligt SLV, http://kostkunskap.blogg.se/2012/june/slvs-saltrad-enligt-slv.html

[25] Karin Olsson, Bertil Öhlin, Läkartidningen nr 17–18, 2012, p 888-92

[26] EFSA. Opinion of the Scientific Panel on Dietetic Products, Nutrition and Allergies on a request from the Commission related to the Tolerable Upper Intake Level of Sodium. Adopted on 21 April 2005. The EFSA Journal (2005) 209, 1-26. http://www.efsa.eu.int/science/nda/nda_opinions/catindex_en.html

[27] W.W. Koo, J.M. Gupta; Breast Milk Sodium Arch Dis Child. 1982 July; 57(7): 500–502 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1627692/?page=2

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[30] William Ganong Review of medical physiology, Lange Medical Publications, Los Altos, CA, USA, 1971

[31] Clinical Chemistry Labs, Landstinget Dalarna, reference value dU-Na 150-300 mmol/d http://www.ltdalarna.se/analysforteckning/ natrium

[32] EFSA. Opinion of the Scientific Panel on Dietetic Products, Nutrition and Allergies on a request from the Commission related to the Tolerable Upper Intake Level of Sodium. Adopted on 21 April 2005. The EFSA Journal (2005) 209, 1-26. http://www.efsa.eu.int/science/nda/nda_opinions/catindex_en.html

[33] EFSA. Opinion of the Scientific Panel on Dietetic Products, Nutrition and Allergies on a request from the Commission related to the Tolerable Upper Intake Level of Sodium. Adopted on 21 April 2005. The EFSA Journal (2005) 209, 1-26. http://www.efsa.eu.int/science/nda/nda_opinions/catindex_en.html

[34] Karin Olsson, Bertil Öhlin, Läkartidningen nr 17–18, 2012, p 888-92

[35] Personal communication Dr Mattias Aldrimer, Falu lasarett, 2012.

[36] Karin Olsson, Bertil Öhlin, Läkartidningen nr 17–18, 2012, p 888-92

[37] Karin Olsson, Bertil Öhlin, Läkartidningen nr 17–18, 2012, p 888-92

[38] EFSA. Opinion of the Scientific Panel on Dietetic Products, Nutrition and Allergies on a request from the Commission related to the Tolerable Upper Intake Level of Sodium. Adopted on 21 April 2005. The EFSA Journal (2005) 209, 1-26. http://www.efsa.eu.int/science/nda/nda_opinions/catindex_en.html

[39] Clinical Chemistry Labs, Landstinget Dalarna, reference value dU-Na 150-300 mmol/d http://www.ltdalarna.se/analysforteckning/ natrium

[40] Aperia, Broberger, Herin, Zetterström Salt content in human breast milk during the three first weeks after delivery. Acta Paediatr Scand; 1979; 68; 441-2

[41] W.W. Koo, J.M. Gupta; Breast Milk Sodium Arch Dis Child. 1982 July; 57(7): 500–502 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1627692/?page=2