Bananas and Your Mood

If some health websites are to be believed, bananas are more than a convenient snack: They're a miracle cure for many conditions. One of these is depression, based on the fact that bananas contain serotonin. You've no doubt heard about this brain chemical, a naturally-occurring neurotransmitter that carries signals along and between nerves. An important function of brain serotonin is to balance mood and contribute to well-being and happiness, which is why many antidepressants are designed to increase levels of serotonin in the brain.

Bananas for happiness: It's an appealing idea, but does it pan out?

There's no question bananas contain serotonin, but grabbing one for a snack or adding it to your smoothie won't lift your spirits when you're down because the serotonin in bananas doesn't cross the blood-brain barrier. In other words, it physically cannot get into the brain to supplement the serotonin that is naturally produced.

Bananas may play an indirect role in affecting mood, however, by shoring up the amount of serotonin the brain is able to make. This is because they're a rich source of vitamin B6, which is necessary for helping the body to synthesize its own serotonin. If you happen to get too little of this vitamin in your diet, eating more of it may help boost your natural serotonin production.

Even then, a banana a day will not keep the blues away. The Recommended Daily Allowance (RDA) for vitamin B6 for adult men and women ages 19 to 50 is 1.3 milligrams (mg). One medium banana has 0.4 mg of vitamin B6, about 20 percent of the RDA, so you'd literally have to eat a whole bunch of them, five bananas, per day if they were your only source of vitamin B6.

It's a good thing, then, that there are plenty of other ways to get the recommended amount of vitamin B6. Plenty of other foods are rich in this nutrient. For instance, a cup of canned chickpeas has 1.1 mg of vitamin B6. The vitamin is also plentiful in proteins like beef liver, yellowfin tuna, sockeye salmon, and chicken breast. Cereal often is fortified with vitamin B6 and even potatoes can compete: a cup of boiled spuds has a much vitamin B6 as a medium-sized banana. (The U. S. Department of  Agriculture (USDA) defines a medium banana as being between 7 inches and 7 7/8 inches long.)

Just because bananas aren't the miracle mood-lifter they've been touted to be doesn't mean they're nutritionally worthless. According to the USDA, a single banana is rich in fiber, for example, one medium fruit has around 3.1 grams of fiber—12 percent of the recommended daily value. Bananas are low in calories (105) and have virtually no fat. At the same time, they're a rich source of potassium, an electrolyte that supports cells in nerves as well as the heart and other muscles. Too little potassium can contribute to high blood pressure (hypertension). You'll also get a decent dose of vitamin C from a banana—17 percent of the daily value for this nutrient.