When you have a Big Mac, medium fry, and a medium Coca-Cola for Lunch, you're not just consuming 1,070 calories, 64 grams of sugar, 43 grams of fat, and 1,150 milligrams of sodium; you're also eating 238,000 microbes -- mostly bacteria, with a few thousand yeast and mold organisms as well.

That's the finding from a trio of scientists at UC-Davis, who, for the first time, tallied the number and type of microorganisms present in the average American diet.

For their study, which was published Tuesday to PeerJ, researchers Jenna Lang, Jonathan Eisen, and Angela Zivkovic purchased and prepared a full day's worth of meals for three separate diets: an average American diet, a USDA-recommended diet, and a vegan diet. The American diet consisted of food from Starbucks and McDonald's, as well as frozen and packaged food from the grocery store. The USDA diet offered cereal, a variety of vegetables, and a turkey sandwich, among other selections. The vegan diet had lots of vegetables, nuts, and fruits, and rounded out with tofu, almond milk, and vegetable protein powder. All of the diets tipped the energy scale at a little over 2,200 calories.

After painstakingly purchasing, preparing, and cooking a day's worth of meals for each diet, the researchers meticulously weighed everything, then obliterated all of it in a blender for analysis.

The USDA diet contained the most microbes, roughly 1.26 billion. The vegan diet came in a distant second at just over 6 million, while the average American diet lagged behind at 1.39 million. Aerobic and anaerobic bacteria dominated the counts. Yeast and mold constituted a far smaller portion.

The researchers were quick to caution that these are only daily estimates, affected largely by the choice of foods. For example, the USDA diet had three foods -- yogurt, Parmesan cheese, and cottage cheese -- which contained live and active bacterial cultures. These sources immensely inflated the microbe count.

Lang, Eisen, and Zivkovic conducted the study because they noticed a dearth of information concerning the microbes that we eat each and every day.

"Far more attention has been paid to the microbes in our feces than the microbes in our food," Lang wrote.

"There could be interesting relationships between the nutritional content of the foods that we eat, the microbes that associate with those foods, and our gut microbiome, not just because we are “feeding” our gut microbes, but because we are eating them as well."

"Further studies are needed to determine the impact of ingested microbes on the intestinal microbiota, the extent of variation across foods, meals and diets, and the extent to which dietary microbes may impact human health."

Source: Lang JM, Eisen JA, Zivkovic AM. (2014) The microbes we eat: abundance and taxonomy of microbes consumed in a day’s worth of meals for three diet types. PeerJ 2:e659 http://dx.doi.org/10.7717/peerj.659

(Image: AP)