What is the relationship between sodium and high blood pressure

Common High Blood Pressure Myths | American Heart Association

what is the relationship between sodium and high blood pressure

Why did the link between sodium and blood pressure generate so . People with high blood pressure benefited even more, reducing their. However, lifestyle choices have allowed many people with a family history of high blood pressure to In some people, sodium can increase blood pressure. Anyone is at risk of a high blood pressure, as blood pressure starts to There was also a positive and highly significant relationship between salt intake and the .

The molar mass of salt is Over the past century, sodium chloride has been the subject of intense scientific research related to blood pressure BP elevation and cardiovascular mortalities.

However, recently some in the academic society and lay media dispute the benefits of salt restriction, pointing to inconsistent outcomes noted in some observational studies 23. Brief history of Salt For millions of years, human beings ate very small amounts of salt 0. Among the food that humans ingest, meat has the highest salt content about 0. During the hunter-gathering period, the main food for human being was meat. In the agricultural period, human beings consumed about the same amount of salt as did their hunter-gathering ancestors 4.

The earliest evidences of salt processing dates back to around 6, years ago. People living in Romania were boiling the salt-laden spring water to extract the salts. The harvest of salt from the surface of Xiechi Lake near Yuncheng in Shanxi, China, dates back to at least BC, making it one of the oldest verifiable saltworks 5. Salt was required as a food preservative for thousands of years. About 5, years ago, the Chinese discovered that salt could be used to preserve food.

Salt then became of great economic importance as it was possible to preserve food during the winter and allowed the development of settled communities. With the increased use of salt, salt became a precious commodity of commerce. Herodotus, an ancient Greek historian, described salt trading routes that united the salt oases of the Libyan desert back in the 5th century BC.

In the early years of the Roman Empire, roads such as the Via Salaria were built for the transportation of salt from the salt pans of Ostia to the capital 7. With the spread of civilization, salt became one of the world's main trading commodities. Much of the food they ate contained salt and its consumption was increasing consequently.

The oppressive salt tax in France was one of the causes of the French Revolution. In India, this tax gave rise to a civil disobedience campaign under Mahatma Ghandi against the British 8. Salt and Human living Salt is an essential electrolyte to life in human beings and is used universally in cooking, seasoning, and preserving manufactured food stuffs around the world.

For several million years, human ancestors ate a diet that contained less than 1 g of salt per day. Salt was the most taxed and traded commodity in the world, with intake reaching a peak around the 19th century 9. However, salt was no longer required as a food preservative with the invention of the refrigerator. Most table salt sold for consumption contains additives. The amounts of additives vary widely from country to country. Iodine is an important micronutrient for humans and iodized table salt has significantly reduced disorders of iodine deficiency.

Salt is present in most foods we eat. However, in naturally occurring foods such as meats, vegetables, and fruits, salt is present in small quantities.

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There is more salt in animal tissues such as meat, blood and milk, than there is in plant tissues Nomads hunted and ate the meat within a few hours of the kill. They do not eat salt with their food, but agriculturalists, feeding mainly on cereals and vegetables, need to supplement their diet with salt Salt intake, Blood pressure, and Human health Sodium serves as an important nutrient in the body and helps nerves and muscles to function correctly.

It is also involved in the auto-regulation of the water and fluid balance of the body. High dietary salt intake presents a major challenge to the kidneys to excrete large amounts of salt administered. One of the main organ systems vulnerable to the adverse effects of excessive sodium in the diet is the cardiovascular system.

Excess dietary sodium predisposes to high BP 13 Changes in salt intake are associated in general with corresponding changes in arterial BP. The association between salt intake in the diet and BP was first suggested by Ambard and Beaujard in They studied 6 patients with high BP for 3 weeks.

They used three kinds of salt and protein content of diets. Salt intake was measured by estimating the salt content of the food and the urine each day.

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When the diet contained little salt, the patients went into negative sodium balance and blood pressure fell, even though the intake of protein was raised. Conversely, when the diet was high in salt, less salt was excreted in the urine so that the patient was in positive sodium balance and the BP rose even when the protein intake was low.

They concluded that it was the salt that primarily affected BP. They had some success in reducing BP by restricting salt intake. InKempner introduced rice diets for the treatment of hypertension. It mainly consisted of rice and fruit. He showed that rice diets containing little salt improved BP, decreased heart size, reversed inverted T waves in the EKG, and ameliorated hypertensive retinopathy.

However, a rice diet did not have widespread acceptability because of insipid and unpalatable features of food contents. The connection between high salt intake and elevated BP became widely recognized after Kempner's rice diet in and thus, high BP was lowered by a low salt diet and a renewed salt restriction strategy utilized in the treatment of hypertension Since then, many animal studies showed a causal relationship between dietary sodium and hypertension and in human studies, established that the average BP in the population is related to habitual salt intake The available data in animal studies confirm the existing relationship between habitual salt intake and BP levels.

what is the relationship between sodium and high blood pressure

A well-documented connection between hypertension and dietary salt intake has been demonstrated in various animals, especially in rats and chimpanzees. Ball and Meneely 18 reported that in groups of young adult rats that were fed different amounts of salt in their diet 0. A similar study had been performed in chimpanzees, which are genetically very close to humans, by Denton et al. The rise in BP was gradual and it was still rising 18 months after they started the high salt diet.

In this study, we can see a progressive increase in BP with added salt and this was completely reversible when the added salt was stopped. Experiments in chimpanzees strongly suggest that essential hypertension is due to high salt intake.

Studies on the effect of salt intake on BP in humans have been carried out extensively for the past several decades. After Kempner's rice diet inother investigators showed the BP lowering effect of a low salt diet Regional differences in habitual salt intake and BP within a population have been studied in various areas of the world.

Around the Newfoundland area, a survey of salt intake revealed that a county in the center of the island had a typical salt intake varying between 6. In contrast, the salt intake varied between 8. This difference in salt intake was accompanied by parallel changes in the incidence of hypertension. Similar evidence had been obtained among the Solomon Islanders Migratory studies also provide evidences of a relationship between habitual salt intake and BP. Studies of population groups that migrated from areas with lower salt intake to areas with higher salt intake have reported increases in BP.

Blood pressure in these migrants rose after a few months 6. Another example of the effect of life-style changes including dietary sodium intake on BP is that of the Yi people, an ethnic minority living in southwestern China. Blood pressure rose very little with increasing age 0. In contrast, Yi migrants and Han people who lived in urban areas consumed a sodium-rich diet and experienced a much greater increase in BP with progressive aging 0.

These findings suggest that changes in life-style, including higher intake of dietary sodium, contributed to higher BP among Yi migrants. A large number of epidemiologic, evolutionary, and clinical studies have confirmed that salt intake is an important factor in elevating the BP in humans.

The first double-blind controlled study of moderate salt restriction was performed in the early 's by MacGregor et al. Patients were advised to reduce dietary salt intake. After 2 weeks of sodium restriction, patients were entered into an 8-week double-blind randomized crossover study of 'Slow Sodium' Ciba, 10mmol of sodium per tablet versus slow sodium placebo. The mean supine BP was 7. They suggested that moderate sodium restriction should become part of the management of essential hypertension.

Followed by this study, many large observational and epidemiological investigations conducted worldwide link between high salt intake and hypertension.

INTERSALT study was one of the first large international epidemiologic studies on sodium intake and hypertension using a standardized method for measuring hour urinary sodium.

Salt and your health, Part I: The sodium connection - Harvard Health

This study, which was a crosssectional assessment of 10, subjects aged sampled from 52 centers around the world, attempted to relate sodium intake to BP from an epidemiological perspective. Sodium excretion ranged from 0. In individual subjects within centerssalt intake was significantly related to BP. Four centers found very low sodium excretion, low BP, and little or no upward slope of BP with age. Across the other 48 centers sodium was significantly related to the slope of BP with age but not to median BP.

The study demonstrated a significant positive relationship between salt intake and BP in individual subjects within centers. In an initial analysis of 48 of the 52 centers, no significant association between sodium intake and median BP was found. However, after inclusion of the remaining 4 centers, in which the average sodium consumption was 0. Furthermore, it also found that populations with low average daily salt intakes had low BP and very little or no increase in BP with age Mean sodium excretion was 0.

what is the relationship between sodium and high blood pressure

Mean BP was Systolic and diastolic BP were not higher at older than at younger ages in men. In women, systolic pressure was lower at older ages. In this tribe, there was a low average population BP, no hypertension and no positive slope of BP with age in a population with very low salt intake. Salt institute criticized that in an initial analysis of 48 of the 52 centers, no significant association was noted between sodium intake and median BP.

However, the INTERSALT's investigators re-analyzed their data and showed that the highly significant within-population association between salt intake and BP across all 52 centers was virtually unchanged. Lowering sodium intake by mmol was associated with a 3mmHg decrease in systolic BP There are several studies on the effect of reducing the salt intake on BP on a community levels.

How to Eat Healthy With High Blood Pressure

In the intervention community, there was a widespread health education effort to reduce the dietary salt intake. The fall in BP involved the whole community, normotensives and hypertensive individuals alike, and the response did not differ between the young and the old or between men and women. Those with the greatest fall in salt excretion tended significantly to be also those who showed the greatest fall in BP.

The other long-term trial was carried out in Tianjin in China as part of a community-based intervention program to reduce non-communicable diseases This intervention was based on examinations of independent cross-sectional population samples in 1, persons and 2, persons in the intervention and matched reference areas. The food recall method was used to measure dietary salt intake. The mean reduction in salt intake was 1. During the same period, the sodium intake increased significantly in men of the reference area.

In the intervention area, the mean systolic BP decreased by 3mmHg for the total population and by 2mmHg for normotensive people. The decrease in systolic BP was significant for both hypertensive and normotensive subjects. Another long-term trial was performed in two Belgian towns of 12, and 8, inhabitants, situated within 50 km of each other The low-sodium intervention in one town was mainly directed at women and implemented through mass media techniques, while the control town was merely observed.

During the study a total of 2, subjects were examined.

what is the relationship between sodium and high blood pressure

However, both systolic BP No significant difference was observed in the evolution of mean systolic and diastolic pressures that declined to the same extent in the two towns during the trial. In women of the intervention town, hour urinary salt excretion decreased by 1. This negative result may be explained by the small reduction in salt consumption that would be insufficient to observe a net effect on BP in the Belgian environment. These results suggest that a reduction in salt consumption is difficult to achieve with mass media techniques and in women and in subjects aged 50 years or more, the intervention did achieve some success, but BP was not affected.

There were many randomized clinical trials performed to test the effects of reducing salt intake on BP. Thirty-two trials with outcome data for 2, subjects were included.

Pooled BP differences between treated and control groups were highly significant for all trials combined. The effects on blood pressure by lowering sodium in hypertensive and normotensive subjects were Weighted linear-regression analyses across the trials showed dose responses, which were more consistent for trials in normotensive subjects.

These analyses yielded estimates, per mmol of sodium reduction, of There is no evidence that sodium reduction as achieved in these trials presents any safety hazards. They concluded that the BP reduction with a substantial lowering of dietary sodium in the US population could reduce cardiovascular morbidity and mortality.

Blood Pressure : Salt's effects on your body

However, in two other meta-analyses 3435it was claimed that salt reduction had very little effect on BP in individuals with normal BP and a reduction in population salt intake was not warranted. The meta-analysis by Midgley et al. Decreases in BP were larger in trials of older hypertensive individuals and small and non-significant in trials of normotensive individuals. They concluded that dietary sodium restriction for older hypertensive individuals might be considered, but the evidence in the normotensive population does not support current recommendations for universal dietary sodium restriction.

Another meta-analysis by Graudal et al. They concluded that these results do not support a general recommendation to reduce sodium intake. However, these two meta-analyses were criticized by some authors because the data included was flawed. Both meta-analysis included trials of very short duration with comparing the effects of acute salt loading to abrupt and severe salt restriction for only a few days.

It is inappropriate to include the acute salt restriction trials in a meta-analysis where the implications of the findings are to apply them to public health recommendations for a long-term.

It is possible that acute and large reduction in salt intake increases sympathetic activity, stimulates the renin-angiotensin system which would counteract the effects on BP. Subsequently, several large-scale intervention studies showing significant antihypertensive effects of salt reduction in diet were performed by several groups. In TOHP I 36the patients were randomized to three life-style change groups weight reduction, sodium reduction, and stress managementone of which was a low sodium diet.

At 18 months follow-up, weight reduction intervention produced weight loss of 3. They concluded that weight reduction was the most effective strategy tested for reducing BP in normotensive persons.

Sodium reduction was also effective for reducing BP.

Salt and your health, Part I: The sodium connection

Compared with the usual care group, BP decreased 2. About million U. High blood pressure is also a major risk factor for stroke. If uncontrolled, high blood pressure can lead to serious and severe health problems. People with high blood pressure have nervousness, sweating, difficulty sleeping and their face becomes flushed. Many people have high blood pressure for years without knowing it.

I read that wine is good for the heart, which means I can drink as much as I want. If you drink alcohol, including red wine, do so in moderation. Heavy and regular use of alcohol can increase blood pressure dramatically. It can also cause heart failure, lead to stroke and produce irregular heartbeats. Too much alcohol can contribute to high triglycerides, cancer, obesity, alcoholism, suicide and accidents. If you drink, limit consumption to no more than two drinks per day for men and one drink per day for women.

Generally, one drink equals a ounce beer, a four-ounce glass of wine, 1. I have high blood pressure and my doctor checks it for me. I was diagnosed with high blood pressure, but I have been maintaining lower readings, so I can stop taking my medication.