When in a committed relationship, most of us have experienced times of diminished sex drive. Such instances may occur when work or school demands and stress are too high, when we're feeling under the weather, when we don't feel as attractive or desirable as we want to be, or when we simply aren't interested in connecting with another person that way.   

It's common for such factors to put off sex from time to time; but when they occur too frequently, many couples turn to "mood setters" such as candlelight, soft music and lingerie to rekindle a spark of passion.

Some couples also turn to specific foods that are purported to increase arousal − foods that are known as aphrodisiacs.

What is an aphrodisiac? 

Aphrodisiacs are substances such as food or supplements that are believed to naturally increase levels of sexual desire, arousal or pleasure, explains Caroline Susie, a registered dietician and national spokesperson for the Academy of Nutrition and Dietetics. They are named after Aphrodite -the Greek goddess of love, desire, and sexuality.

Aphrodisiacs commonly include "foods, herbs or even scents that are thought to spark romantic feelings or increase libido," says Lauri Wright, a registered dietitian nutritionist and director of nutrition programs at the University of South Florida College of Public Health. She adds that aphrodisiacs are often considered "a natural way to get in the mood." 

In that context, sometimes people also refer to behaviors as aphrodisiacs. For instance, exercise and physical fitness have been shown to cause some people to want to be more intimate. Some couples also improve their sex lives by swimming frequently.

Do aphrodisiacs work? 

But speaking only of aphrodisiacs as foods or other consumable substances, there's very little evidence that any of them actually increase libido; "and no food has been scientifically proven to stimulate human sex organs," says Susie. 

At the same time, there are people with hormonal issues related to thyroid function or menopause who may notice that certain aphrodisiac-like foods "can help them balance things out," Wright explains. Moreover, "if someone is dealing with high stress or anxiety, any foods that improve your mood or promote relaxation may consequently enhance your libido."

It's also worth noting that while foods don't specifically cause arousal, some foods may help with sexual function, especially in people with certain health conditions. People who have blood circulation problems, for instance, may be helped by eating foods that relax blood vessels and improve blood flow to the genitals. This is one of the properties of erectile dysfunction medications like Viagra. 

Specifically, there's an amino acid in nuts and meat called L-arginine that becomes converted to nitric oxide in the body, which can increase blood flow. Ditto for foods containing omega-3 fatty acids or foods like apples and onions that contain quercetin as it too has anti-inflammatory properties that can improve blood flow. 

Which foods are aphrodisiacs? 

With such factors in mind, these are the foods that are often thought of as being aphrodisiacs. While they haven't been shown to directly increase feelings of sexual arousal, they do have properties that may improve sexual function or promote feelings of relaxation that are associated with lovemaking:

• Oysters are probably the most well known aphrodisiac because they are rich in zinc, "which is important for hormone production and sexual health," says Wright.
• Alcohol is another common one - but it's a double-edged sword. While one small study found that drinking red wine may promote romantic feelings, alcohol is also associated with sexual dysfunction. 
• Dark chocolate is another popular aphrodisiac because it's "high in phenylethylamine, which can boost your mood," says Susie. "But there's conflicting research on whether it actually boosts sex drive."
• Strawberries are thought of as improving sex drive as well because they are high in vitamin C, which can improve blood flow and reduce stress. And the body uses the folic acid in strawberries to create sperm cells. 
• Salmon and avocado may improve sexual function as well because they both contain omega 3 fatty acids, which stimulates hormone synthesis and can reduce anxiety. 
• Saffron is a spice that's similarly known for enhancing one's mood, Susie notes, and has also been shown to improve erectile function in individuals taking antidepressants.
• Honey is another food that's considered to be an aphrodisiac because it's "high in B vitamins and boron, which help regulate hormone levels and energy," says Wright
• Pistachios can also be beneficial, Susie says, because they are high in protein, fiber and healthy fats, "which may help in lowering blood pressure and reducing symptoms of erectile dysfunction."
• Peppers may help as well, Wright says, because the capsaicin in hot peppers "can boost your heart rate and trigger the release of endorphins, which might make you feel more energized and excited." 

Beyond food, some supplements or libido pills are also often advertised as improving sex drive, but such products are not regulated the same way food and drugs are. "Be wary of pills or supplements that make grand promises without scientific backing," Wright cautions, "as some may contain harmful ingredients or interact negatively with medication."

If you have ongoing concerns about your libido or other related issues, "talk to your doctor," recommends Susie. "There are proven medical solutions that can address and yield more results than, say, consuming 50 oysters a day as Casanova was rumored to have done."