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Posted in Our Blog on March 2, 2019
Could your fad diet make you more susceptible to foodborne infection? Research studies say yes. A University College Cork study in Ireland took a look at high fat diets and susceptibility to Listeria monocytogenes infection. Could there be a Keto and Listeria risk? Again, it may be a yes.
Their approach was in response to their desire to study the impact on “westernized diet” of high fat and how it relates to infectious disease. “In the context of a global epidemic and changes in dietary habits towards increased consumption of a ‘westernized’ diet, there is currently surprising little information regarding the influence of diet upon the progression of infectious disease.”
This got me thinking. The “westernized diet” is generally considered to be high fat, high carbs, high sugars. This is influenced by our leaning toward fast food McDonald’s, Burger King, Wendy’s, and so on. When not consuming fast food, we eat a lot of meat and carbs in most meals as compared to some other cultural diets.
This study didn’t address carbohydrates and sugars. They only explored fat content of diets. This immediately made me think about a high-fat diet craze so many people I know are doing.
These hard-core dieters are eating butter and cream cheese by the pound. But it seems to be working for most of them. This is supposed to be a diet? I am sure you have heard of it. Keto. Short for the metabolic phase they are trying to achieve – ketogenesis.
But what exactly is Keto?
According to Harvard University, the keto diet moves beyond the low carb, low fat people tend to think about when dieting to lose that extra weight. A true ketogenic diet is different. “Unlike other low-carb diets, which focus on protein, a keto plan centers on fat, which supplies as much as 90% of daily calories.”
In normal metabolism, the body uses sugar, more specifically glucose that comes from carbohydrates like fruits, vegetables, grains, and legumes as fuel. The keto diet uses ketone bodies as fuel. Ketone bodies are produced by the liver from stored fat.
This is not an easy feat to achieve and requires a very strict diet. But hey, if you can trick your body into burning fat by consuming fat it sounds like a win-win, right?
This requires the dieter to deprive themselves of carbohydrates. This means they must consume less than 20 to 50 grams of carbs per day. “Keep in mind that a medium-sized banana has about 27 grams of carbs.” So, if you are a banana fan, you can’t monkey around with that fruit.
It doesn’t happen overnight. It could take several days to reach a state of ketosis. Meanwhile you are consuming large amounts of fat. Sounds a little counter-productive to me. But my friends swear by it.
Additionally, eating too much protein can have a negative affect on achieving ketosis. Those that I know that do this. Those hard-core keto people. They track macro and micro nutrients, protein, and everything. It certainly is a juggling act and a biochemistry final exam stressor for dieting.
A typical keto diet with 2,000 calories per day will have “165 grams of fat, 40 grams of carbs, and 75 grams of protein.” That is a lot of fat!
Which is concerning to me, because this study talks about how a high fat diet makes you more susceptible to pathogenic infection. Specifically, Listeria monocytogenes as explored in this study involving mice.
But what is Listeria monocytogenes?
Listeria monocytogenes commonly known as Listeria is a bacterium that causes the infection listeriosis. Lots of vowels in there, I know. But it is a very serious foodborne infection. Pregnant women, newborns, older adults, and those with a compromised immune system are most at risk. Pregnant women often experience less severe symptoms, though they are at greater risk of stillbirth and miscarriage. Symptoms include normal flu-like symptoms such as fever, fatigue, and muscle aches. Additional symptoms include headache, stiff neck, loss of balance, confusion, and convulsions.
One of the reasons reading this study made me think about Listeria is because I often associate Listeria with dairy. Unpasteurized or under pasteurized dairy products and dairy products in general are high on the list of Listeria risk. Most of the people I know on this keto diet use a lot of cheese to obtain the fat content in their diet. One guy makes what he calls fat bombs with cream cheese, butter, and coconut oil.
Now we know what the keto diet is. And what Listeria is. Back to the study to see if there is a link. Spoiler alert! I wouldn’t be writing about it if there wasn’t a link. But keep reading because it gets good.
Back to the Study
The scientists conducting the study had 3 sets of rats. One set was fed a high fat diet (happy rats with a short life). The second was fed a low-fat diet (poor guys never got to have a muffin). The third set acted as a control and were fed a normal rat chow (yes, rat chow is a thing).
After they chowed down on their respective meal plans for 13 days all rats were exposed to Listeria monocytogenes. Fecal, intestinal, spleen, and other samples were obtained over the next few days.
After exposure, the rats fed the high fat diet showed changes in their microbiota (also known as the gut microbiome – and the intestine’s first line of defense against pathogens). Additionally, they showed an increase in the number of goblet cells. These are known binding sites for the pathogen. The microbiota also changed to promote inflammation in the hosts intestine.
Those fed the low-fat diet and rat chow didn’t have any noticeable differences in microbiota or goblet cell production.
What Does This Mean?
The high fat diet altered the rats’ intestinal microbiome. In addition to affecting the normal flora of the intestines, the body produced cells that made the rats targets for pathogens. In this case, they looked specifically at the cells that bind to Listeria. Other changes in the intestines made the rats more prone to inflammation.
Decreased immunity. Increased targets. And more inflammation. To Listeria.
That seems pretty scary to me. My friends can keep their keto. I’ll just settle for low carb and low sugar. It seems to be working for me.
By: Heather Van Tassell, Contributing Writer (Non-Lawyer)