An episode of the TV show Two and a Half Men titled “Aunt Myra Doesn’t Pee a Lot” raises a question that perhaps you’ve asked yourself: Why do some people seem to pee so much more than others?

Patients have asked me what’s normal regarding frequency of urination, the color of urine, or why its smell changes after eating certain foods. Here are some answers.

The numbers of urinating

How often a person pees varies tremendously, though most people go between four and eight times a day.

In healthy people, the key factor is how much fluid they consume through food and drink. Even Jake, the young child in Two and a Half Men, gets this connection. When he complains that his father got up four times in the middle of the night to pee, his father corrects, “One of those was to get a glass of water.” Jake retorts, “There’s your problem! Stop topping off the tank!”

Some sources estimate that the average person produces about six cups of urine a day. But, given the high variability in drinking habits, urine volume varies widely.

Other factors that affect frequency and volume of urination are bladder size and how long a person delays urination. Men tend to have somewhat larger bladders than women. And people who “hold it” may go less often with a larger volume each time. But the total daily volume of urine is still determined mostly by fluid consumption.

Problem numbers

Oliguria, the medical term for very low urine output, can be a sign of kidney failure. In adults, it is defined as urinating less than about one-and-three-quarters cup a day. But since most of us don’t pee into measuring cups at home, the strict definition isn’t usually of much use to the average person.

Having to go more often than usual can be a sign of a urinary tract infection, diabetes, or other important medical conditions. The general rule is to see your doctor if there’s been a significant increase or decrease in the frequency of urination or output that can’t be explained by how much you drink.

All the colors of the rainbow

If you are getting enough water, your urine should be pale yellow. If you’re even slightly dehydrated, your urine will be darker. The yellow color is thanks in large part to old blood cells, which, after getting broken down in several steps, get excreted through the urine and act as the pigmenting agent. And the less water in your bladder to dilute the urine, the brighter the color.

Some people focus on the color of their urine, convinced that good health requires it to be a certain color. That’s usually unnecessary. If you eat a healthy diet and drink when thirsty, your kidneys will produce urine that keeps your body’s fluid and electrolyte balance where it should be.

What if your urine is red, brown, or even green? Chances are you can blame something you ingested. Vitamins can turn urine a very bright yellow or, in the case of vitamin C, give it an orange tint.

Here are some common food-color links:

  • Beets and blackberries can turn your pee red.
  • Eating a lot of carrots can lead to orange urine.
  • Asparagus can lend your urine a green color (and a funky odor—more on that in a minute)
  • Large amounts of fava beans, rhubarb, and aloe can turn your pee dark brown.

Interestingly, studies show that foods don’t impact everyone’s urine color in the same way. For example, in one study some people who ate beets had urine that was darker and redder than usual, while others who ate the same amount did not. (When the urine that did not darken was studied under the microscope, a slight red color could be seen.)

One potential cause for this difference is the variable pH balance of different people’s urine. It seems that beet’s red pigments lose their color at either extreme of the pH scale.
And just because you peed red after a beet salad once doesn’t mean it will happen every time—studies show that the response changes. The difference may be because you ate a different type of beet, the beets were prepared differently, or the beets were harvested at a different time.

Many medications can alter the color of your urine. For example, the antidepressant amitriptyline and the pain and inflammation drug indomethacin can turn your urine blue! And other drugs have been linked to green urine.

Dark red or brown urine may be due to blood or muscle protein in the urine. Sometimes the blood is due to something as benign as strenuous exercise. Other times, it’s a sign of a urinary tract problem, such as an infection (which typically also causes a burning sensation during urination) or bladder or kidney disease. Muscle inflammation (myositis) or damage (such as after an injury) may cause a muscle protein called myoglobin to leak into the urine.

Foamy urine could mean there is protein in the urine. The kidneys normally keep protein out of the urine so this could be an indication of kidney disease.

Other medical conditions ranging from lead or mercury poisoning to liver and kidney disease can also change the color of your urine, so if you have weird-colored urine and can’t think of a food or medication link, or if your urine color is abnormal for more than a day or so, see your doctor.

Can’t you smell that smell?

Just as the amount of liquids you ingest impacts urine’s color, it also impacts its smell.
A chemical called urea smells like ammonia and gets excreted in urine. The more concentrated the urea (meaning the less water in the urine), the stronger the smell. Smell can also change depending on the foods you eat. The most obvious example is asparagus. For some (but not all) people, eating asparagus makes their urine smell strange—some describe it as smelling like rotten cabbage.

Some sources blame the sulfur-containing fertilizers that were first used on asparagus plants around 1800 for the smell it causes—before that, there’s no record of anyone describing the vegetable causing urine odor. Others suggest that the sulfur-containing proteins in asparagus are broken down only by those who carry a particular gene. Yet another explanation suggests that only certain people can smell the change in odor caused by the digestion of asparagus.

The bottom line

There is still much about urination that’s not well understood. But this much is clear: The kidneys are remarkably good at producing urine with just the right amount of water and other chemicals to keep you healthy. So don’t panic if your urine seems different than usual from time to time. Chances are it’s just a sign of your kidneys doing their job.

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