High Phosphate Diet Impacts Nervous System, Induces Hypertension

Diets rich in phosphate additives, commonly found in processed foods, can increase blood pressure by triggering a brain signalling pathway and over activating the sympathetic nervous system that regulates cardiovascular function, UT Southwestern researchers discovered. Their findings could lead to treatment strategies for patients with hypertension caused by overconsumption of foods containing high levels of phosphates.

Inorganic phosphate is often used as a preservative or flavour enhancer in packaged foods, processed meats, and other dietary staples. As a result, the study reports, the average adult in developed countries consumes phosphate far above the recommended daily allowance.

 The research outlines a new paradigm for this previously unclear mechanism and identifies a potential target for developing treatment strategies.

Hypertension occurs when the pressure that pushes against a patient’s arterial walls is too high. Affecting nearly half of the U.S. population⁽⁵⁾, according to the U.S. Canters for Disease Control and Prevention, hypertension increases the risk of life-threatening medical events such as heart attack and stroke. 

UTSW researchers ran a series of tests that measured and compared FGF23 protein levels, mean arterial pressure, and renal sympathetic nerve activity in rats receiving a high (1.2%) phosphate diet and another group on a normal (0.6%) phosphate diet. The measurement was repeated during stress response to exercise by stimulation of the spinal cord.

Researchers found that those on the high phosphate diet showed increased levels of FGF23 protein in their serum, cerebrospinal fluid, and brain stem, and that FGF23 proteins were able to cross the blood-brain barrier, causing high blood pressure both at rest and during physical stress.

Analysis also revealed that inhibiting fibroblast growth factor receptor 4 (FGFR4) during simulated exercise dampened the negative effects of a high phosphate diet, suggesting a connection between FGFR4 and overactivation. Inhibition of FGFR1 did not have the same effect.

Given these results, researchers explored the role of FGFR4 and found that activation of this receptor contributes to an exaggerated increase in blood pressure during simulated exercise. FGFR4 activation caused by an excess of dietary phosphate was accompanied by an increase in the protein calcineurin A and brain stem activity that may contribute to elevated blood pressure and overactivation of the sympathetic nervous system during simulated exercise.

What’s high in phosphate additives? Some foods on this list may surprise you

Phosphate/phosphorus is generally listed among the ingredients in food products as additives including dicalcium phosphate, disodium phosphate, monosodium phosphate, trisodium phosphate, sodium tripolyphosphate, or tetrasodium pyrophosphate.

• Beverages: Dark colas, beer/ale, cocoa, drinks made with milk, canned iced teas, chocolate drinks

• Dairy products: Cheese, ice cream, pudding, custard, cream soups, yogurt

• Packaged, prepared foods: Snacks, frozen meals, pre-cooked items

• Processed meats: Sandwich meat, hot dogs, sausage, bacon

• Fast foods: Burgers, chicken nuggets, fish sandwiches, French fries, and other fast foods, which often contain phosphate additives for preservation and texture

• Others: Pizza, chocolate, caramel

Source: National Kidney Foundation

Reference:

1. https://www.ahajournals.org/doi/full/10.1161/CIRCULATIONAHA.124.071605

(Newswise/MKJ)