Guest Blogger, Liz Schultz, Undergraduate in Microbiology
For a sister, an older brother can be the ultimate protector and yet her greatest enemy. I have the privilege of having two older brothers. Growing up, I had to face things like being held up to the ceiling fan and being told I would have my head cut off if I didn’t make some lemonade. Being too young to understand the laws of physics, I really did believe that fan would act like a guillotine and chop my head clean off. To make up for these moments, my brothers often protected me from everyone else, and I love them, even if they do have a secret evil side.
I received a call last month that my oldest brother was being flown to a hospital in Sioux Falls, SD, after collapsing at work. His heart was not functioning correctly, and the doctors were worried that he might need a pacemaker. My brother is only 29, and we have no history of heart problems in my family, so this was troubling. What could have caused a young person to have such a malfunctioning heart? The doctor said my brother has had high blood pressure for some time causing his heart to struggle to work properly. The source of his high blood pressure was most likely from his high-sodium diet.
My brother’s case is not rare. In the United States alone, one in three adults has high blood pressure. The doctor was correct in saying that a high-sodium diet can be to blame for these high numbers. But my brother doesn't munch purely on chips – even if they are absolutely delicious – so how could his diet become so sodium filled? Two words: food safety. Our nation has become obsessed with pathogens in our foods. Any food related outbreaks become national news overnight. Our meats are packaged a certain way, many foods are heat sterilized, and foods have extra chemicals added to them to minimize the risk of dangerous pathogens.
One of the favorite chemicals companies like to add to foods has been good old sodium chloride, or table salt. Not only can it enhance the taste, but salt also lowers the water activity of a food, or the water molecules not bound to other molecules in the food and available for microbes to utilize. Pure water has a water activity of 1 (the highest possible water activity), and normal dehydrated foods have a water activity between 0.2 to 0.5. The higher the available water content, the more water there is for microbes to exploit. Most bacteria need a range from 0.88 to 0.96. When salt is added to a food, it lowers the available water content to a range where some microbes can no longer grow. Reducing the water activity can also cause osmotic stress on the cell, causing the microbe to shrivel up like a raisin and die. The food containing this salt can now have a higher shelf life and inhibits those annoying, dangerous pathogens.
While our foods can be safer because of these high salt practices, our health can pay the price. Normally, the kidneys do a good job of regulating salt in our bodies, but if our intake of sodium becomes too high, the kidneys can fall behind. As the levels of sodium increase, the body begins to retain more fluid to maintain the water balance so that our cells can function properly. More fluid in the body means that the heart has to pump more fluid. The addition of this fluid causes an increase in pressure in the walls of our blood vessels, causing high blood pressure. Extended periods of high blood pressure can cause hypertension, which causes serious cardiovascular problems over time if not reversed.
Is increasing the salt in foods just to make them safer really worth it? Microbiologists and researchers will be weighing this question over the coming years, and maybe they will find new ways to make our foods safer without risking our health in the process.
This entry is part of the fall MICR 354 scientific writing students' blog series.
Image: CDC/Amanda Mills