Dear Dr. Roach: I love fish and chips. I eat them once a month. I have tuna and other fish throughout the month, as well. Quite often, the fishy odors linger for days until all remnants have left my body. Is there anything I can do to counteract the smell? I feel that others can tell when I have eaten fish. The odor comes from my mouth, my urine and my feces.


Dear J.C.A.: Fish, particularly deep-saltwater fish, contain a substance called trimethylamine oxide. After fish die, it is converted by bacteria and enzymes in the fish to trimethylamine, which is largely responsible for the “fishy” odor; it gets stronger over time. Trimethylamine in humans is excreted through sweat in addition to urine and feces. People have different amounts of the enzyme that breaks down TMA, so there’s a variance in the noticeable effect of fishy breath and sweat after consuming fish. A very few people lack the enzyme entirely.

TMA can be washed off of fish, and also can be broken down by acid, such as in lemons. Rinsing fish before cooking or using lemon during or after cooking will lessen the odor effect on you.

Other foods also may cause an evident odor in the sweat and urine. Cruciferous vegetables like broccoli and asparagus can change the odor of urine and sweat, as can garlic, onions and some spices. Alcohol, especially in excess, can be picked up by people with sharp noses. Men who ate no meat for two weeks were found to have a “more pleasant” body odor than those who did.

Dear Dr. Roach: I have a mole on my left hand and wonder if liquid nitrogen can be used to remove it.


Dear D.R.B.: There are many different kinds of skin lesions, and the term “mole” is not specific. The most common skin lesion called a mole is a melanocytic nevus (a melanocyte is a pigment-making cell in the skin, so most moles are darker than underlying skin; the word “nevus” is a Latin term meaning “birthmark,” but some moles are present at birth while others are acquired during lifetime). These are benign lesions, and do not require any treatment other than watching them to be sure they do not change or grow, which might indicate a more serious skin condition.

A dermatologist evaluating a skin lesion will consider whether it is concerning enough to remove. If so, the specimen is sent for pathological evaluation. Liquid nitrogen is not used to remove a concerning mole, as the pathologist needs to have the architecture, which requires a sharp biopsy.

There are other benign lesions that can be treated with liquid nitrogen. For example, a seborrheic keratosis is a dark, raised, “stuck-on”-appearing lesion that may resemble a wart or a mole. If the clinician examining it is sure of the diagnosis, then liquid nitrogen is an effective way of removing it, with a good cosmetic result.

Email questions to

Read or Share this story: