Eating Meat, Dairy, Eggs, and Fish Can Make Your Breath Stink!

You know the old say­ing, “You are what you eat.” To that, we can add anoth­er one, “You smell like what you eat.” My father-in-law learned that les­son when he served in the Per­sian Gulf Com­mand dur­ing World War II. He heard that the local peo­ple in Iran com­plained that the Amer­i­can sol­diers smelled like sour milk. He laughed it off at the time; but when he got back to the Unit­ed States after the war, he noticed the same thing. Peo­ple who had been eat­ing the stan­dard Amer­i­can diet did smell like sour milk! Peo­ple who had been eat­ing Per­sian food did not. The rea­son was sim­ple. The Amer­i­cans were eat­ing far more meat and milk and eggs and fish than the Per­sian peo­ple were.

Eat­ing a lot of ani­mal pro­tein makes you stink. It can give you bad breath, bad body odor, and ter­ri­bly stinky gas. Part of the prob­lem is the sheer over­load of pro­tein that you get from ani­mal-based foods. The oth­er part of the prob­lem is that ani­mal pro­tein tends to be par­tic­u­lar­ly rich in the sul­fur-con­tain­ing amino acids. When you eat more of these sul­fur-con­tain­ing amino acids than your body needs, your body will sim­ply break them down to burn them for ener­gy. In the process, it can pro­duce some very stinky byprod­ucts.

Pro­tein is made up of strings of amino acids. To make your own body’s pro­teins, your cells need an ade­quate sup­ply of up to 20 dif­fer­ent amino acids. You need to get eight of them ready-made in your food. It’s easy to get enough pro­tein, includ­ing enough of all eight essen­tial amino acids, from any prac­ti­cal plant-based diet as long as you are eat­ing enough food to get enough calo­ries. So you don’t real­ly need to wor­ry about pro­tein defi­cien­cy.


If you eat too much fat, your body can store the excess fat in your fat cells. But eat­ing too much pro­tein does NOT cause your body to build big­ger mus­cles. Instead, your liv­er will con­vert the sur­plus amino acids to sug­ar, which will then be burned for ener­gy. Unfor­tu­nate­ly, when your liv­er con­verts amino acids to sug­ar, it releas­es some nasty byprod­ucts. In the long run, an over­load of these byprod­ucts can dam­age your liv­er, kid­neys, and bones. In the short run, they can make you stink.

Ani­mal pro­teins tend to be par­tic­u­lar­ly rich in sul­fur-con­tain­ing amino acids. Besides cys­teine and methio­n­ine, which your body can use for mak­ing pro­tein, ani­mal foods also con­tain tau­rine and homo­cys­teine. When these sub­stances are bro­ken down, they release sul­fur com­pounds. The methyl mer­cap­tan (CH3-SH) that is pro­duced from the break­down of methio­n­ine is a major con­trib­u­tor to bad breath. These smelly com­pounds can also be excret­ed in sweat. Even an excess of some of the non-sul­fur amino acids can pro­duce stinky byprod­ucts. For exam­ple, the break­down of tryp­to­phan by bac­te­ria in the intes­tine pro­duces ska­tole, which is large­ly respon­si­ble for the smell of feces.

Den­tal prob­lems can cause bad breath because the bac­te­ria in the mouth can release some smelly com­pounds, includ­ing methyl mer­cap­tan. Thus, brush­ing and floss­ing are impor­tant. How­ev­er, some of the odors in breath come from else­where in the body. The smelly chem­i­cals can be car­ried to the lungs by the blood­stream and exhaled with the breath. The clas­sic exam­ples are the ketones that are pro­duced when some­one is fast­ing or has untreat­ed type 1 dia­betes. Low-carb diets tend to cause hor­ri­ble breath for two rea­sons: ketones plus the over­load of stinky sub­stances from the high pro­tein intake.

Bad breath and body odor should be viewed as a warn­ing sign. Eat­ing too much methio­n­ine can make you stink, but it can also pro­mote the growth of can­cer. A change in diet can make a big dif­fer­ence in how you look and how you smell. A friend of mine was pleas­ant­ly sur­prised by those ben­e­fits when she went on a plant-based diet for weight loss. First, she noticed that her acne cleared up. Then, she noticed that she no longer had a prob­lem with body odor.

Behind Barbed Wire_PrintUpdate: For more infor­ma­tion about why low-car­bo­hy­drate diets make peo­ple smell bad, see my book Thin Dia­betes, Fat Dia­betes: Pre­vent Type 1, Cure Type 2.

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