Blood pressure is the force exerted by circulating blood against the walls of the body’s arteries. Hypertension is diagnosed if, when it is measured on two different days, the systolic blood pressure readings on both days is ≥140 mmHg and/or the diastolic blood pressure readings on both days is ≥90 mmHg.
Several studies recognize the relationship between hypertension and dietary sodium intake. A reduction in dietary sodium not only helps lower the incidence of hypertension, but also reduces morbidity and mortality from cardiovascular diseases.
Normally our kidneys are efficient at regulating the sodium and water levels of our blood. But, eating too much salt can disturb this balance, increasing sodium levels in the blood. This leads to more water retention thereby increasing the volume of blood in our bloodstream. As blood volume increases, the pressure on blood vessels also increases making it harder for the heart to pump blood. This can lead to stiffening of blood vessels and increases the risk of hypertension.
Following are some mechanisms via which sodium can contribute to development of hypertension:
- Altered sympathetic activity in response to increased blood volume
- Increased blood volume causes shear stress and an increase in wall tension of the arteries
- Increased blood volume over a period of time causes an increase in the expression of collagen fibers. This leads to reduction in the ratio between elastin and collagen fibers contributing to progressive increase in arterial wall stiffness.
- Altered renin- angiotensin- aldosterone mechanism
WHO defines consumption above 5g / day as an excessive sodium intake & recommends 2.0 g per day (equivalent to approximately 5.0 g salt per day) in the general population.
Salt & sodium recommendations per 100 gm of food
Depending on how the body reacts to changes in dietary salt intake with alterations in blood pressure, hypertensive patients can be classified as “salt sensitive” and “salt resistant” groups. Salt sensitive individuals are those whose blood pressure values respond dramatically to changes in the dietary salt intake.
Along with restriction of salt intake, other lifestyle interventions like __ Dietary Approaches to Stop Hypertension can bring a considerable improvement in both systolic & diastolic blood pressure. It is very important to note that more than 80% of excess salt intake comes from salt added to processed foods (e.g., sandwiches, pizza, soups) and not from salt added by the during cooking. Thus, avoiding processed food is one of the best ways to cut on sodium intake in a diet.
Salt consumption at home can be reduced by:
- not adding salt during the preparation of food
- not having a salt shaker on the table
- limiting the consumption of salty snacks
- choosing products with lower sodium content.
Other local practical actions to reduce salt intake include:
- Integrating salt reduction into the training curriculum of food handlers
- Removing salt shakers and soy sauce from tables in restaurants; Introducing product or shelf labels making it clear that certain products are high in sodium
- Providing targeted dietary advice to people visiting health facilities
- Advocating for people to limit their intake of products high in salt and advocating that they reduce the amount of salt used for cooking; and
- Educating children and providing a supportive environment for children so that they start early with adopting low salt diets.
REFERENCES:
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https://www.who.int/news-room/fact-sheets/detail/hypertension
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Frisoli, T. M. et al. (2012) ‘Salt and hypertension: Is salt dietary reduction worth the effort?’, American Journal of Medicine, 125(5), pp. 433–439. doi: 10.1016/j.amjmed.2011.10.023.
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Grillo, A. et al. (2019) ‘Sodium Intake and Hypertension’, Nutrients, 11(9). doi: 10.3390/NU11091970.
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Haddy, F. J. (2006) ‘Role of dietary salt in hypertension’, Life Sciences, 79(17), pp. 1585–1592. doi: 10.1016/j.lfs.2006.05.017.
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The DASH Diet | National Kidney Foundation (no date). Available at: https://www.kidney.org/atoz/content/Dash_Diet (Accessed: 18 February 2022).
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Rodriguez-Iturbe, B., Romero, F. and Johnson, R. J. (2007) ‘Pathophysiological Mechanisms of Salt-Dependent Hypertension’, American Journal of Kidney Diseases, 50(4), pp. 655–672. doi: 10.1053/j.ajkd.2007.05.025.
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Rust, P., & Ekmekcioglu, C.(2016). Impact of Salt Intake on the Pathogenesis and Treatment of Hypertension. Hypertension: From Basic Research to Clinical Practice, 61–84. doi:10.1007/5584_2016_147
