Low Sodium Intake And Cardiovascular Risk
Over the years, the evidence of a close relationship between high sodium intake and hypertension, and high sodium intake and increased cardiovascular risk and mortality, has become increasingly consolidated. For this reason, we are used to consider that the lower the sodium intake is, the better the patient prognosis is. However, the studies that are beginning to shake the foundations of this historic fortress are growing in number. Actually, in the analysis of this topic, several cohort studies and meta-analyses have shown that the relationship between sodium intake and poor patient prognosis have not a linear trend, but rather describe a J-shape curve. In these studies, an increased risk not only in high sodium intake, but also in significantly low sodium intake levels is underlined. To reach this declaration, large patient populations have been studied, including various types of healthy patients or those with different co-morbidities , with wide numbers in all subgroups.
Sodium Intake And Blood Pressure Values
Available evidence suggests a direct relationship between sodium intake and blood pressure values . Excessive sodium consumption has been shown to produce a significant increase in BP and has been linked with onset of hypertension and its cardiovascular complications . Conversely, reduction in sodium intake not only decreases BP levels and hypertension incidence, but is also associated with a reduction in cardiovascular morbidity and mortality . A large meta-analysis showed that modest reduction in salt intake for four or more weeks causes a significant fall in BP in both hypertensive and normotensive individuals, irrespective of sex and ethnic group, and larger reductions in salt intake are linked to larger falls in systolic BP . However, the current health policies have not reached an effective achievement for the reduction of dietary sodium in the population and the positive effects of a reduced sodium intake on BP levels tend to decrease with time, owing to poor dietary compliance.
In this paper, we have reviewed the evidence regarding the effects of sodium intake on arterial function, and their implication in the pathogenesis of hypertension. We have first addressed the debate on salt-sensitivity, in light of recent evidence, and then discussed the effects of sodium handling on arterial function and structure.
Myth : You Should Eat Or Drink More Salt After Working Out
Salt comes out of your body in two ways through urine and through perspiration but that doesnt mean you need to add extra salt to your diet every time you break a sweat.
Some products, like sports drinks, are advertised as a good way to replace lost salts after working out. Under usual circumstances, sports drinks that contain electrolytes are not necessary for rehydration the process of replacing lost fluids and salts. Tap water and consuming a healthy diet will help replace any nutrients lost during any activity. You can read more about good hydration and how to avoid dehydration here.
Sports drinks can be used to rehydrate if you have exercised continuously for 90 minutes or more. If youre thinking about starting a new and more strenuous exercise regime and wondering about how to rehydrate properly, its a good idea to talk to your doctor about how this might affect your health and your dietary needs.
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Myth : You Can Tell That A Food Is Salty By Tasting It
Some foods with a high salt content wont taste very salty at all. Many packaged foods that contain a lot of salt have other ingredients that balance out the salty flavour, so that the salt is effectively hidden in the food.
You can visit the Heart Foundation and VicHealths website Unpack The Salt to find out more about reducing hidden salts in your diet.
Lifestyle Changes Can Help
One of the first things your doctor will recommend is modifying your lifestyle by:
- Eating a low-sodium diet , especially if youre at risk.
- Limiting alcohol.
- Exercising regularly.
- Maintaining a healthy weight.
Even with salt restriction and lifestyle changes, blood pressure may remain elevated, Dr. Laffin notes. Medications, in addition to lifestyle changes, are oftentimes also needed to lower your blood pressure. Examples of medications include:
- Diuretics, or water pills, which increase urination to help discharge excess fluid.
- Angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers , which help to relax blood vessels.
Besides encouraging you to keep hypertension and diabetes under control, your doctor may test you annually for kidney disease.
Working with your doctor to ensure that salt intake is not raising your blood pressure and impacting your heart and kidneys can have a dramatic impact on your health and longevity.
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Monday 12 November 2018
Salt its a natural resource found everywhere from the ocean to our tears, its tasty and it can be really cheap to buy. But like many things, too much salt isnt great, especially for our health.
Because its linked to Australias biggest killer cardiovascular disease salt is talked about a lot in health messaging and the media. But some messages about salt need to be taken with a grain of, well, salt. Weve busted some salt myths to make it easier for you to stay healthy.
Does Circulating Eo Help Maintain Normal Bp
When circulating EO was reduced by 50% by infusion of normal rats with anti-ouabain antibodies, mean BP was not affected, although the adrenal cortex hypertrophied, presumably to help increase EO production . Severe hypotension may occur in adrenocortical insufficiency because of the loss of aldosterone and cortisol, but perhaps also in part because of the lack of adrenal EO production and very low plasma EO levels . Also, as already noted, the EO level rises in normal human subjects when a diuretic is administered to deplete body Na+ this response suggests that EO may help prevent a drop in BP in this case. Finally, BP normally declines modestly during the first two trimesters of pregnancy in normal women and rodent dams and then rises to or slightly above the prepregnancy level during the third trimester. In pregnant 2R/R mice, however, the third trimester rise in BP is significantly attenuated . This implies that the 2 Na+ pump high-affinity ouabain binding site and its ligand EO play a role in helping to maintain normal physiological BP in pregnancy.
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Misperceptions About Salt Reduction
- On a hot and humid day when you sweat, you need more salt in the diet: There is little salt lost through sweat so there is no need for extra salt even on a hot and humid day, although it is important to drink a lot of water.
- Sea salt is not better than manufactured salt simply because it is natural. Regardless of the source of salt, it is the sodium in salt that causes bad health outcomes.
- Salt added during cooking is not the main source of salt intake. In many countries, about 80% of salt in the diet comes from processed foods.
- Food does not need salt to have appealing flavour. It takes some time for a persons taste buds to adjust, but once they get used to less salt, one is more likely to enjoy food and notice a broader range of flavours.
- Food has no flavour without salt. Whilst this may be true at first, taste buds soon become accustomed to less salt and you are more likely to enjoy food with less salt, and more flavour.
- Foods high in salt taste salty. Some foods that are high in salt don’t taste very salty because sometimes they are mixed with other things like sugars that mask the taste. It is important to read food labels to find out sodium levels.
- Only old people need to worry about how much salt they eat: Eating too much salt can raise blood pressure at any age.
- Reducing salt could be bad for my health: Its very difficult to eat too little salt since there are so many everyday foods containing salt.
Myth: I Was Diagnosed With High Blood Pressure But I Have Been Maintaining Lower Readings So I Can Stop Taking My Medication
High blood pressure can be a lifelong disease. Follow your healthcare professionals recommendations carefully, even if it means taking medication every day for the rest of your life. By partnering with your healthcare team, you can successfully reach your treatment goals and enjoy the benefits of better health.
Written by American Heart Association editorial staff and reviewed by science and medicine advisers. See our editorial policies and staff.
Last Reviewed: Oct 31, 2016
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A New Look At Sodium And Blood Pressure
Moore and her team took data from 2,632 men and women aged between 30 and 64 years, who were part of the Framingham Offspring Study an offshoot of the Framingham Heart Study. All participants had normal blood pressure at the start of the trial.
Over the 16-year follow-up period, the researchers observed that the participants who consumed under 2,500 milligrams of sodium each day had higher blood pressure than those who consumed higher quantities of sodium.
The results seem counterintuitive. As the authors write: While we expected dietary sodium intake to be positively associated with both SBP and DBP , the opposite was found.
Although the findings appear to kick against the status quo, they are in line with other recent studies asking similar questions. Research has shown that there is a J-shaped relationship between cardiovascular risk and sodium. This means that low-sodium diets and very high-sodium diets both carry a higher risk of heart disease.
Many people in the United States sit in the middle of this curve, where the cardiovascular risk is at its lowest.
We saw no evidence that a diet lower in sodium had any long-term beneficial effects on blood pressure. Our findings add to growing evidence that current recommendations for sodium intake may be misguided.
Lynn L. Moore
Is Sodium Really That Bad Ive Seen Research That Questions The Connection Between Sodium And Health Problems
The science behind sodium reduction is clear. Significant evidence links excess sodium intake with high blood pressure, which increases the risk of heart attack, stroke and heart failure.
While some newer research questions the link between sodium and health problems, the connection is well-established. The newer research adds to a larger discussion that has evolved over the last few years about salt intake but does not replace the existing evidence.
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About Salt Sodium And Potassium
- Sodium is an essential nutrient necessary for maintenance of plasma volume, acid-base balance, transmission of nerve impulses and normal cell function.
- Excess sodium is linked to adverse health outcomes, including increased blood pressure.
- The primary contributors to dietary sodium consumption depend on the cultural context and dietary habits of a population.
- Sodium is found naturally in a variety of foods, such as milk, meat and shellfish. It is often found in high amounts in processed foods such as breads, processed meat and snack foods, as well as in condiments .
- Sodium is also contained in sodium glutamate, used as a food additive in many parts of the world.
- Potassium is an essential nutrient needed for maintenance of total body fluid volume, acid and electrolyte balance, and normal cell function.
- Potassium is commonly found in a variety of unrefined foods, especially fruits and vegetables.
- Increased potassium intake reduced systolic and diastolic blood pressure in adults.
Where Does All The Sodium Come From
Table salt is a combination of two minerals about 40% sodium and 60% chloride.
Here are the approximate amounts of sodium in a given amount of salt:
- 1/4 teaspoon salt = 575 mg sodium
- 1/2 teaspoon salt = 1,150 mg sodium
- 3/4 teaspoon salt = 1,725 mg sodium
- 1 teaspoon salt = 2,300 mg sodium
More than 70% of the sodium we consume comes from packaged, prepared and restaurant foods. The rest of the sodium in the diet occurs naturally in food or is added when were cooking food or sitting down to eat . So even if you never use the salt shaker, youre probably getting too much sodium.
Because most of the sodium you eat is in your food before you buy it, it can be hard to limit how much youre getting. But you deserve to choose how much sodium you eat. An AHA survey found that about three-quarters of adults in the U.S. prefer less sodium in processed and restaurant foods.
Learn about the sources of sodium in the American diet and food supply. And watch out for the Salty Six the six common foods that add the most sodium to the diet.
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Peripheral Sympathetic Innervation And The Consequences Of Increased Sympathetic Drive
Tonic sympathetic drive is the predominant mechanism for maintaining vascular tone, and a block of 1-adrenoceptors in vivo rapidly lowers arterial myocyte , dilates arteries , and reduces BP . Thus augmented SNA should elevate BP directly. This sympathetic nerve-mediated vasoconstriction and elevation of BP must surely come into operation when the central sympathetic drive increases, as in the case of a sudden, short-term rise in CSF . Compensatory mechanisms, including the baroreflex response and endothelium-mediated vasodilation, should, however, counter the tendency for a sustained, large elevation of BP unless they are downregulated , a subject we address below.
The topic of increased SNA usually focuses on augmented norepinephrine release and rapid activation of vasoconstriction the roles of the cotransmitters, ATP and neuropeptide Y , are often ignored. Release of the cotransmitters is greatly influenced by the pattern of SNA and increases with bursts of activity moreover, ATP and NPY both modulate the effects of norepinephrine on smooth muscle . Of particular interest in the present context is the fact that NPY, especially, is a mitogenic agent and growth regulator that may make an important contribution to vascular remodeling .
Think Twice About Table Salt
Table salt is quite high in sodium, with about 2,400 mg in a single quarter of a teaspoon. While it is not the major source of sodium in the diet, adding table salt to foods before even tasting them can bump up sodium consumption by quite a bit.
Instead, using herbs and spices to flavor foods, tasting foods before adding table salt, and considering pepper instead of salt and pepper can lower sodium content of the diet.
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This May Be Why Slashing Salt Lowers Blood Pressure
Slash sodium from your diet. That’s the advice inevitably given to everyone.
Restricting sodium intake has been key to reducing blood pressure. Now researchers may have found an underlying mechanism to explain why.
Scientists examined hundreds of metabolites substances produced during digestion from blood samples drawn in a study among 64 black British residents with high blood pressure, or hypertension. All participants were instructed to follow a reduced-sodium diet, but otherwise none were taking medication or receiving treatment for their condition.
The researchers discovered reducing sodium intake resulted in higher levels of two specific metabolites, both associated with lower blood pressure levels and arterial stiffness.
The study taps into the science of metabolomics, which examines how tiny molecules react to changes in their environment. In this case, the sodium levels altered the setting.
While everyone in the study was put on a low-sodium diet, half were given a slow-release sodium tablet for six weeks. The others received placebos. Researchers then switched the pills for an additional six weeks.
“We know reduced sodium intake reduces blood pressure and cardiovascular risk. However, the underlying biological mechanisms are not well established,” said Dr. Haidong Zhu, lead author of the study published Monday in the American Heart Association’s journal Hypertension.
“That’s an important group of people to continue studying,” she said.
The Roles Of Eo And Ang Ii In The Brain
The effects of Na+-rich CSF on SNA, heart rate , and BP are also mimicked by icv infusion of ouabain and blocked by the conjugation of EO with icv Digibind . Intravenous infusion of the same total amount of Na+ or ouabain used in the icv infusions does not affect SNA, HR, or BP. Like icv Na+-rich CSF or icv aldosterone, a high-salt diet increases hypothalamic EO content in SHRs and Dahl S rats . Thus it seems that Na+-rich CSF stimulates the synthesis of aldosterone in the brain and that this, in turn, triggers the local synthesis and secretion of EO. Furthermore, the aldosterone-induced alteration of AT1R, NADPH oxidase, and nNOS protein expression may be mediated by an EO-2 Na+ pump-protein kinase signaling cascade because it is blocked by Digibind .
The brain mechanisms that control the BP set point are also likely regulated by these BP neuromodulatory mechanisms. The nucleus tractus solitarus in the medulla, which receives input from other medullary cardiovascular control centers as well as from peripheral baroreceptors, serves as a comparator to detect the offset between the set point and baroreceptor signals. The nucleus tractus solitarus projects to the paraventricular nucleus and hypothalamic circumventricular organs, such as the subfornical organ, that are directly involved in sympathoexcitation and, as just described, are modulated by the Aldo-EO-ANG II pathway .
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What Is Salt And How Does It Affect Our Blood Pressure
Salt has been used to flavour and preserve foods for thousands of years. We all need some salt for good health but eating too much can increase our blood pressure, increasing our risk of heart disease. Here we discuss how too much salt can increase blood pressure, the relationship between salt and high blood pressure across Europe and what we can do to reduce our salt intake.