Resistant Hypertension (HTN) is diagnosed when the patient's blood pressure (BP) remains at 140/90 or higher despite being on 3 or more anti-HTN drugs. Clinical trials have shown that between 20 and 30% of the people in America with HTN now have resistant HTN.

While most patients initially diagnosed with HTN can have their BP "controlled" by BP drugs, the longer the patient follows the typical medical treatment model the more likely it is they will require more and more drugs to get their BP below 140/90. Eventually taking even 3 or more BP drugs cannot "control" their BP. This failure of modern medicine to prevent and treat HTN begins with its failure to recognize and successfully deal with salt toxicity, which is the known primary causal factor of primary HTN and is the main factor driving BP higher over time.For the first time ever, researchers evaluated the effects of consuming a low-salt diet on the BP of patients with resistant HTN. They also examined dietary salt-related changes in the RAAS system, blood volume and arterial stiffness that occurred in just one week on either a low-salt or high-salt diet. The study participants included 12 mostly overweight and obese people with resistant HTN ages 34-66. Their average BP at entry to the study was 145.8/83.9mmHg despite taking an average of 3.4 BP drugs. The subjects were then fed for one week either a low salt (<50mmol or 1150mg of Sodium/day) or high salt (>250mmol or 5750mg of Sodium/day) diet. The low-salt diet was provided by the researchers and was designed to be nutritionally similar to their usual diet except that it was much lower in salt. In just one week the average BP of the subjects on the low-salt diet dropped to 122.8/74.9. By contrast, after one week on the high-salt diet their BP was 145.6/84.0. The researcher also assessed 24 hour ambulatory BP on the 2 diets and found it averaged 150.3/82.1 on the high-salt diet and 130.0/72.8 on the low-salt diet. The authors of this study said their results "…suggest that patients with resistant hypertension are particularly salt-sensitive and emphasizes the importance of low dietary salt intake in the clinical management of resistant hypertension." They also found evidence that this BP reduction was due in part to a reduction in blood volume and a decrease in arterial stiffness.The authors also stated that: "All of the subjects enrolled into the current study reported having been previously advised to lower their dietary salt intake, and all reported having done so." However, they also noted not one of the subjects had received expert dietary counseling to reduce salt intake. An initial 24-hour urine test showed that the average sodium intake for these subjects was 194.7mmol, which would correspond to a daily salt intake of 11.6g.Bottom line:The results of this study on resistant HTN clearly demonstrate the failure of modern medicine to focus on the main cause of primary HTN, which is salt toxicity. Most physicians focus treatment primarily on pharmacological treatment instead of diet, which will ultimately fail to keep BP even below the hypertensive range (<140/90) and rarely return BP to its normal physiological range of around 110/70. It also clearly demonstrates most people diagnosed with a disease caused largely by excess salt ought to be referred to RDs for expert dietary counseling as the dietary advice provided by physicians typically provides little or no benefit. With 70+ million Americans now diagnosed with HTN and over 15 million with resistant HTN it is clear that the FDA should reclassify salt as something other than "GRAS" and start taking steps to limit the amounts added to foods. It also provides yet more evidence that should push Congress to pass the MEAL Act or other legislation that would require the amount of sodium added to restaurant foods to be listed on the menu.By James J. Kenney, PhD, RD, FACN For more information on salt and diet, visit foodandhealth.com - Click CPE Courses under By Media at the top of our site. Scroll down the CPE page to Salt Toxicity.