By: Heather Williams
When you think about DNA mutation, some may think about Sci-Fi genre transformation, turning into a human/animal hybrid or with super-human abilities. That is a far fetched possibility like something out of the movies. Others may think about something more realistic like cancer and how the cells spontaneous or under stress do not form properly causing mutant DNA to continue replicating. But what if what you eat could change your DNA? Researchers have discovered that is a very real possibility, specifically with respect to food poisoning.
A study at Cornell University explored Salmonella as a cause for DNA mutation. In short, one interview indicated they suspect it could make future food-borne illness episodes last longer. The questions about the long-term affects are continued to be studied. The research author and Doctoral Candidate in Food Science at Cornell University, Rachel Miller, related this affect on DNA to a sunburn. “We apply sunscreen to keep the sun from damaging our skin,” explains Miller. “If you don’t apply sunscreen, you can get a sunburn – and possibly develop skin problems later in life.” She says, “The more you expose your body’s cells to DNA damage, the more DNA damage that needs to be repaired, and there may one day be a chance that the DNA damage is not correctly repaired.” When the DNA damage is not correctly repaired, you have cells replicating and making more of those mutated cells.
Different Types of Salmonella
The study primarily focused on Typhoidal Salmonella, but additional work was done on Non-Typhoidal Salmonella. But what does that mean? There are several types of Salmonella. This study focused on two types, Non-Typhoidal Salmonella and Typhoidal Salmonella. Initially researchers were only focused on Typhoidal Salmonella, then performed small experiments on more common forms Salmonella. Non-Typhoidal Salmonella is the most common form and is responsible for food poisoning. The rarer Typhoidal Salmonella, caused by Salmonella Typhi, is the bacteria responsible for typhoid fever.
Typhoidal Salmonella is rare in the United States. While around 5,700 cases are reported in the US each year, about 75% are from Americans who have travelled internationally. Few people contract the disease within the contiguous United States. Typhoid Fever is still very common in developing countries around the world, affecting about 2.5 million people each year. Symptoms include high fever (103ºF to 104ºF), stomach pain, weakness, loss of appetite, and headache. Some patients may have a rash of flat, rose-colored spots. Patients presenting symptoms who have had an exposure risk are diagnosed with the illness with a fecal analysis. More serious complications include Focal Infection, when the bacteria “takes root” in the body tissue. This may cause illness of arthritis (affecting joints and connective tissue) or endocartitis (affecting the muscle of the heart).
According to the Centers for Disease Control and Prevention (CDC) Non-Typhoidal Salmonella is the leading cause of bacterial diarrhea worldwide, affecting 94 million cases of gastroenteritis and accounting for 115,000 deaths. Gastroenteritis is the most common affect of Non-Typhoidal Salmonella. While the incubation period is 6 – 72 hours, most infections will present symptoms within 12 -36 hours after exposure. Typical symptoms include abdominal pain, acute diarrhea, fever, and sometimes vomiting. Most people recover without treatment and symptoms usually last for 4 – 7 days. Those seeking treatment are often treated for the symptoms such as dehydration and fever. Fecal analysis can determine Non-Typhoidal Salmonella infection. Major complications such as Reactive Arthritis are a concern for the very young, the very old, and those with compromised immune systems. Reactive Arthritis occurs in 2 – 15% of patients. Symptoms of Reactive Arthritis include inflation of joints, eyes, reproductive organs, and urinary organs. These more serious ailments may appear 18 days after infection.
But How Does It Change My DNA?
Researchers discovered that Salmonella Typhi from Typhoidal Salmonella produces a toxin that attacks host cells and causes damage to DNA. When researchers looked at more common forms of Salmonella, such as the Non-Typhoidal Salmonella found in strains typically seen in food poisoning, they found that they also have the potential to produce that toxin because they also had the genes found in Typhoidal Salmonella that contribute to expression of that toxin. They performed experiments on lab-grown human cells and found that there were clear signs of DNA damage on the cells exposed to the toxin. These cultures were analyzed for damage to the DNA, and mutations from the expected DNA sequences were observed.
So what does this mean? The bacteria responsible for Typhoid Fever are closely related to the bacteria that causes food poisoning. This bacteria can produce a toxin that will damage you DNA. While DNA is resilient enough to repair itself, over time mistakes in DNA may occur. This permanently changes that DNA and allows it to replicate and keep making copies of that misspelled DNA. In essence, the more times you have food poisoning, the more opportunities exist for your cells to be exposed to the toxins that can permanently alter your DNA.
Now, what does that mean for your body? Researchers will continue to explore those answers. But on the basic level, changes in those cells containing the misspelled DNA will change how the cell behaves and does the job of that particular cell. At this time researchers believe that it will make subsequent infections last longer and more symptomatic.
How Can I Protect Myself?
Salmonella infections usually occur when human or animal feces contaminated with the bacteria come in contact with food, water, or hands are not washed after coming in contact with it. Foods most likely to contain salmonella include contaminated water, raw or undercooked meat, raw or undercooked eggs, and raw milk. Outbreaks commonly associated with Salmonella include poultry, eggs, and meat, however other foods such as fruits and vegetables have been contaminated in the past.
No vaccine is available at this time against Non-Typhoidal Salmonella infections. The best way to protect yourself is to prevent food poisoning from happening to reduce your risk of repeat exposure. Prevention measures are aimed at avoiding foods and drinks which are high risk for contamination with Salmonella. Be sure to thoroughly cook meat and eggs and wash fruits and vegetables.
Additional things you can do to protect yourself include frequent hand washing, especially after contacting animals or their environment, as well as taking additional water and food precautions while traveling outside of the United States.