It is important to understand that part of the reason that high blood pressure and salt consumption are associated with processed foods is because processed foods are loaded with refined carbohydrates. For over a century, research has demonstrated that carbohydrate consumption leads to water and sodium retention and therefore raises blood pressure. This effect is what University of Wisconsin endocrinologist Edward Gordon described as the, remarkable sodium and water retaining effect of concentrated carbohydrate food.
In short, the amount of carbohydrates we consume in our diet changes our need for salt. In high carbohydrate (high processed food) diets the typical American diet today our kidneys retain water by inhibiting the excretion of sodium (salt). In low carbohydrate diets, and by this I mean fat burning, low insulin states where one consumes less than 60 grams of carbohydrates per day, the opposite occurs. Therein, the kidneys increase secretion of sodium (and water) in a mechanism that works, in effect, like the antihypertensive (blood pressure lowering) drugs known as diuretics. The diuretic phenomenon induced by a low carbohydrate state is described as the, natriuresis of fasting.
What does this mean for JumpstartMD patients?
For one, we actually encourage our patients on a low-carb, fat burning diet to ingest liberal amounts of fluids (100 ounces per day) and sodium to replenish their losses. Strategies to replenish sodium while following a low-carb lifestyle include liberal use of the salt shaker at the table and /or by consuming 1 gram (range 1-2 grams assuming patient is not hypertensive or on blood pressure medications in which doses may need to be tempered) of sodium each afternoon in 2 cups of warm water typically through warmed bouillon or broth. Sodium replenishment is particularly beneficial during the first couple of weeks of a low carbohydrate diet wherein the greatest fluid shifts occur. Thus we encourage sodium replenishment during that period but then tailor that intake to each individuals needs thereafter. Because the bodys salt metabolism is uniquely different when adapted to a low-carb state through more efficient excretion of salt and water, this simple strategy will help avoid many of the easily preventable side effects associated with sodium depletion and dehydration: headache, fatigue, constipation, weakness, and dizziness with standing.
Secondly, our patients blood pressures typically improve greatly not only because of their weight loss and exercise but independently as a result of carbohydrate restriction. How do we know that weight loss and exercise are not the sole means of improving our patients blood pressures? Because blood pressures typically improve significantly in the first week of treatment in a low carbohydrate state, long before the majority of their weight loss has occurred or an exercise routine commenced. This is a result of the decreased sodium and water retention induced by a low carbohydrate, low insulin state.
But there is also research to support the idea that fully keto-adapted individuals (those whose bodies have adapted to a low-carb state over several weeks of carbohydrate restriction under 60 grams of carbs per day) show blood pressure improvements through mechanisms independent of the kidneys. Mechanisms such as increased peripheral vascular dilation (a good thing to improve high blood pressure) and decreased sympathetic nervous system (fight or flight response) stimulation.
Bottom line, processed foods are loaded with sodium in a high-carb milieu in which the sodium is most problematic. Which of these two culprits leads to elevations in blood pressure the sodium or the carbohydrate? Id argue its the latter. We see tremendous improvements in blood pressure derived from properly delivered low carbohydrate diets. When in this low-carb state, the body handles salt differently and needs to be proactively managed to prevent easily avoidable side effects. Lastly, in keeping with the JumpstartMD message of eating whole, real, fresh, non-processed foods, I hope one can see from this blog how sodium in itself is not inherently bad and, in fact, is an essential and critically important electrolyte. That said, when combined with a diet replete with refined carbohydrates in processed foods, our bodies cannot handle the additional sodium load. But sodium is not the problem. Its the carbs. Eat well. Eat real food. And stay healthy.