Hypertension And Salt Intake - Does It Really Matter?

The World Health Organization (WHO) estimates that over 1 billion people worldwide are affected by hypertension, and many more are unaware of the condition as there are no apparent symptoms [1]. Blurred vision, headaches, dizziness or nosebleeds are commonly experienced by people who are diagnosed with high blood pressure [2]. Hypertension is diagnosed when a person experiences persistent blood pressure levels above 140/90 mmHg [1]. The cause of hypertension is yet unknown, but contributing factors have been identified. Smoking, alcohol abuse, physical inactivity, stress level and calorie-dense, nutrient-poor diets are known to progress hypertension [1].

However, one mineral has caught the medical and scientific community’s particular attention over several decades. Sodium is an abundant trace mineral in our body. It is essential for maintaining fluid balance and normal nerve and muscle function. Sodium can be found in many foods today, especially when sodium is bound to chloride, also called salt [3].


Is salt really that bad for you?

Sodium plays a vital role in fluid balance because of its inert ability to attract water. Therefore, consuming salt in excess amounts attracts and retains water. Consequently, blood vessels expand due to the high water volume and increase the pressure in the arterial walls. Our kidneys help by excreting the excess salt and water as urine to reduce the high pressure exerted on the walls. If the pressure on the arterial walls persists for a long time, the walls can rupture, blood starts leaking into tissues causing stroke or ischemic heart disease [4]. Due to its natural property to attract water, salt raises blood pressure in healthy and sick populations.

Salt is widely used in the industrial kitchen because it enhances taste, adds flavour, and conserves foods naturally, making them last longer. Its consumption today is between 6 to 12 grams per day [3]. The main salt source is processed foods, which account for up to 75% of total salt intake [5].

Globally, the goal is to reduce salt intake to under 5 grams a day which equates to one teaspoon of table salt [1]. The American Heart Association (AHA) recommends an ideal intake below 3 grams of salt per day. Studies have shown a dose-dependent relationship between salt consumption and blood pressure: the less salt is consumed, the lower the blood pressure [6].


Can consuming not enough salt be a health risk?

Not all patients benefit from salt restrictions. Scientists estimate that about 51% of people living with hypertension are salt-sensitive, which means their blood pressure drops when they reduce their salt intake. The other half does not experience significant changes in blood pressure levels when restricting salt consumption [7].


Public health campaigns that aim to reduce salt intake are often based on studies that have a systematic bias. As a consequence, controversies around salt intake arose. The participants in these studies are mainly salt-sensitive and hypertensive or overweight. This poses important questions about how these results can be translated to a healthy population with normal weight and blood pressure levels [8]. Adler et al. agree that a decrease in salt consumption is advisable, but the clinical benefit of a salt reduction on cardiovascular mortality is still questionable [9].

Reviews and meta-analyses have addressed these common biases and concluded that further reductions of salt intake, as the WHO and AHA recommend, do not show any further benefits and may increase the mortality rate. The National Academy of Medicine (NEM) questions the recommendation for people living with hypertension or diabetes. The evidence shows neither beneficial nor adverse health outcomes of eating as little salt as possible [8].


How can I reduce blood pressure levels effectively?

Salt is part of a healthy diet. Its core component, sodium, has many vital functions in our body. However, too much salt can progress hypertension. Processed foods such as french fries, various condiments, and cured meats lead to an excess salt intake. Most of these foods are high in sodium, fat, and sugar, making them hyper-palatable, leading easily to overconsumption.

In the context of pre- and hypertension, patients need to address their salt intake, and its reduction needs to be part of the medical treatment. By focusing on eating minimally processed foods as much as is achievable, many people decrease their salt intake concomitantly.

On the other hand, reducing salt intake as much as possible is currently not supported by the evidence. Micromanaging and fearing salt are not clever strategies and probably do not support healthy, long-term, and sustainable change. When changing eating behaviours, it is helpful to focus on the foods you can add in, instead of feeling discouraged by looking at what you need to consume less of.


How to lower blood pressure with dietary and lifestyle changes


Add potassium

Potassium can be found in milk, fruits and vegetables. Contrary to salt, potassium can reduce blood pressure significantly [10]. For example, by mixing one cup of milk with a banana, a handful of nuts, and a cup of spinach, more than half of the daily potassium requirement can be covered. Potatoes, prunes, lentils, artichokes and dried beans are an excellent source of potassium, too.

Drink water with your meals

Johnson et al. found that sugary drinks can increase blood pressure levels. They conclude that the type of fluid intake should be addressed and considered when treating patients with hypertension [11]. In a study, healthy subjects were asked to eat a salty soup, one day with and one day without water. Through this experiment, the scientist found out that blood pressure levels were unaffected if the participants drank water concomitantly [12].

Add herbs and spices

Lemon, celery, ginger, chilli, garlic, dill, oregano, basil, rosemary, parsley, thyme, vinegar, and many more can be used to add more depth and flavour to dishes. Ready-made blends such as za’atar, sumac, garam masala or Mediterranean herbs are a great choice as well. Taste buds take 6 to 8 weeks to adjust to a new flavour. We can learn and unlearn salt preference [13].


Add exercise to your daily routine

All types of physical activity are beneficial. Cornelissen et al. found that isomeric resistance training reduced systolic blood pressure levels greater than endurance or dynamic resistance training [14]. An isomeric resistance exercise involves the engagement of muscles without moving around, such as a wall sit or plank hold [15]. Tai Chi is also highly recommended. Chan et al. found greater blood pressure reductions in the group that practised Tai Chi than in the brisk walk or control group [16].


Add foods high in calcium and magnesium

These minerals have beneficial effects on hypertension as they help the blood vessels to relax [17]. Calcium is found in milk, yoghurt, and cheese. Magnesium is found in dark chocolate, green leafy vegetables, whole cereals, and nuts. Supplements are not recommended because they may result in adverse health effects [18].


This article was written by Dejana Simic BSc and edited by Mei Wan FdSc, BSc (Hons), RD, MBDA, an HCPC Registered Dietitian and Nutritionist.

Dejana obtained a Bachelor of Science in Nutritional Sciences at The University of Vienna and is part of Mei Wan's Nutrition and Health Writer Volunteer Team.

Contact Dejana on Instagram @coachdejana


Are you worried about your heart health and confused about how to reduce your salt intake? Are you struggling with high blood pressure and want to lose weight? Book your free 15 discovery call with Mei to find out how she can help!


References

  1. World Health Organization (WHO). Hypertension. 2019 September. Accessed March 2021 via [https://www.who.int/news-room/fact-sheets/detail/hypertension]

  2. British Heart Foundation (BHF). High blood pressure - symptoms and treatment. Accessed March 2021 via [https://www.bhf.org.uk/informationsupport/risk-factors/high-blood-pressure/symptoms-and-treatment]

  3. Alan Aragon: Hold my sodium: when public health recommendations are wrong. Alan Aragon Research Review. August 2020; 16-18.

  4. Silverthorne U. Dee: Human Physiology. An Integrated Approach. Pearson Education 8th Edition; 482

  5. Action on Salt: UK Salt Reduction. Accessed March 2021 via [http://www.actiononsalt.org.uk/uk-20salt-20reduction-20programme/145617.html/]

  6. Antmann ET et al.: Stakeholder Discussion to Reduce Population-Wide Sodium Intake and Decrease Sodium in the Food Supply. Circulation. May 2014; 129:e660–e679. Accessed March 2021 via [https://www.ahajournals.org/doi/10.1161/CIR.0000000000000051?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%20%200pubmed]

  7. Pilic L. et al.: Salt-sensitive hypertension: mechanisms and effects of dietary and other lifestyle factors. Nutrition Reviews. October 2016, 75(10): 645-658. Accessed March 2021 via [https://academic.oup.com/nutritionreviews/article/74/10/645/2749228]

  8. Graudal N. et al.: Conflicting Evidence on Health Effects Associated with Salt Reduction Calls for a Redesign of the Salt Dietary Guidelines. Prog Cardiovasc Dis. May 2018, 61(1):20-26. Accessed March 2021 via [https://www.sciencedirect.com/science/article/pii/S0033062018300835?via%3Dihub]

  9. Adler AJ et al.: Reduced dietary salt for the prevention of cardiovascular disease. Cochrane Library. December 2014. Accessed March 2021 via [https://www.cochrane.org/CD009217/VASC_reduced-dietary-salt-prevention-cardiovascular-disease]

  10. Aburto NJ et al.: Effect of increased potassium intake on cardiovascular risk factors and disease: systematic review and meta-analyses. BMJ. April 2013, 3;346:f1378. Accessed March 2021 via [https://pubmed.ncbi.nlm.nih.gov/23558164/]

  11. Johnson RJ et al.: Hyperosmolarity drives hypertension and CKD—water and salt revisited. Nature Reviews Nephrology. May 2014, 10; 415-420. Accessed March 2021 via [https://www.nature.com/articles/nrneph.2014.76]

  12. Kanbay M. et al.: Acute effects of salt on blood pressure are mediated by serum osmolality. J Clin Hypertension. September 2018, 10; 1447-1454. Accessed March 2021 via [https://onlinelibrary.wiley.com/doi/full/10.1111/jch.13374]

  13. National Kidney Foundation. Top 10 Tips for Reducing Salt in Your Diet. Accessed March 2021 via [https://www.kidney.org/newsletter/top-10-tips-reducing-salt-your-diet]

  14. Cornelissen VA et al.: Exercise training for blood pressure: a systematic review and meta-analysis. J Am Heart Assoc. February 2013, 1;2(1):e004473. Accessed March 2021 via [https://pubmed.ncbi.nlm.nih.gov/23525435/]

  15. Jesica Salyer: 5 Examples of Isomeric Exercises for Static Strength Training. Accessed March 2021 via [https://www.healthline.com/health/fitness-exercise/isometric-exercises]

  16. Chan AWK et al.: Tai Chi exercise is more effective than brisk walking in reducing cardiovascular disease risk factors among adults with hypertension: A randomised controlled trial. Int J Nurs Stud. December 2018; 88:44-52. Accessed March 2021 via [https://pubmed.ncbi.nlm.nih.gov/30195124/]

  17. Harvard Health Publishing. Key minerals to help control blood pressure. 2014 July. Accessed March 2021 via [https://www.health.harvard.edu/heart-health/key-minerals-to-help-control-blood-pressure]

  18. The Association of UK Dietitians (BDA). Hypertension and Diet: Food Fact Sheet. Accessed March 2021 via [https://www.bda.uk.com/resource/hypertension-diet.html]