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Erections occur when the penis fills with blood, making it rigid, longer, and thicker. While erectile dysfunction (ED) has many possible causes, from the neurological to the physical, the ones nutrition can address are vasodilation — the widening of blood vessels to allow greater blood flow — and hormonal imbalances caused by nutritional deficiencies.

Our evidence-based analysis on erections features 21 unique references to scientific papers.

Research analysis led by and reviewed by the Examine team.
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Summary of Erections

Overview | How are erections assessed? | What affects erections?


The ability to achieve and maintain erections when aroused is a common health issue for many men.[1] While women don’t experience the phenomenon in the same way, inadequate blood flow to female genitalia is also common — and sometimes related to the same phenomena.

Aging is the biggest risk factor for ED, but there are a host of other contributing factors,[2] such as diabetes, vascular disease, low testosterone,[3] and hypothyroidism.[4]

The potential causes of ED generally revolve around vasodilation — the widening of blood vessels — which allows the penis to accommodate more fluid, thus allowing it to become erect. Nitric oxide is a chemical messenger that tells blood vessels to dilate; a breakdown in signaling is a common reason for ED and high blood pressure.

Nitric oxide precursors and substances that lead to greater nitric oxide synthesis are commonly found in drugs and supplements aiming to improve erections. Sex hormones are involved in nitric oxide synthesis, and men with low testosterone are more likely to have ED. Anything that leads to dysfunction in the walls of the blood vessels, such as smoking, inactivity, and excessive body fat, can increase ED risk as well.

Sometimes ED isn’t a breakdown in vasodilation or a hormonal problem but secondary to psychological issues of anxiety and anhedonia — a diminished ability to feel pleasure. In this case, while some libido-enhancing supplements may be useful, the answer may not be found in supplements or dietary modification.

How are erections assessed?

💡 Tip: Talk to your physician

It can be a little uncomfortable speaking with a physician about sex. But if you have or are experiencing some level of ED, you should tell your physician.

ED can be a sign of other health problems, such as blockages in your blood vessels or nerve damage caused by diabetes. If you don't consult a physician, these problems may go unidentified and untreated.

A urologist, who specializes in urinary and sexual issues, is best and can assess ED through a series of medical and sexual history questions. They may also perform a mental health screening and physical exam.

During the exam, your urologist may ask you some of the following questions.

  • How would you rate your confidence that you can get and keep an erection?

  • How often is your penis firm enough for intercourse?

  • How often are you able to maintain an erection during sexual intercourse?

  • Do you have an erection when you wake up in the morning?

  • Do you use illegal drugs, drink alcohol, or smoke?

While it can be uncomfortable, the more accurate your answers, the better medical care your physician can provide.

What are the symptoms of erectile dysfunction?

ED can manifest itself in a few different ways, including the following.

  • The inability to get an erection at all

  • A partial erection that is insufficient for intercourse or masturbation

  • An initial erection that is prematurely lost during intercourse or masturbation

  • An intermittent and inconsistent ability to get or maintain an erection

What affects erections?

💡 Tip: Talk to your partner

Those with ED have reported feeling bad about themselves or shame regarding their condition, which can be a barrier to seeking treatment and enjoying sexual activity.

ED can be a difficult topic for partners to discuss with each other. Couples who do not openly talk to each other are more likely to have problems with sexual intimacy. Likewise, men who have trouble talking about their feelings may be unable to share their sexual concerns with their partners.

If you have trouble communicating, counseling can be very helpful. Finding a way for both you and your partner to express your feelings and desires, and then work on the issues together, can make a big difference.


Supplements that have been shown to have a positive effect on ED mostly relate to how they can improve nitric oxide signaling and vasodilation. Some notable supplements include maca, arginine, and cocoa polyphenols.

The table below displays an analysis of human studies and indicates how supplements may affect erections.

Diets & foods

For both men and women, blood flow to sexual organs is one of the major features of arousal, and this is achieved with nitric oxide,[5][6] a chemical that signals blood vessels to widen, or dilate. Sildenafil (Viagra) works by increasing nitric oxide signaling but does not affect nitric oxide synthase (NOS), the enzyme responsible for producing nitric oxide.[7]

The effect of NOS can be enhanced by compounds found in a wide variety of plants,[8] and your body makes nitric oxide from the nitrate in your food or from the amino acid arginine. Some foods and supplements can help with not just male erections but also clitoral and vaginal blood flow.[6]

Vegetables sorted by nitrate content (milligrams per 100 grams)

Very high

Arugula/rocket, collard greens, dill, turnip greens

(100 to <250)

Beetroot, bok choy, celeriac, celery, kale, kohlrabi, lettuce, mustard greens, parsley, radishes, rhubarb, spinach, swiss chard, turnips, watercress

(50 to <100)

Broccoli, cabbage, cauliflower, endive, Savoy cabbage

(20 to <50)

Chicory, eggplant, fennel, green beans, green onions, leeks, pumpkin/squash

Very low

Artichokes, asparagus, broad beans, brussels sprouts, carrots, cucumbers, dried beans, garlic, lima beans, maize, mushrooms, onions, peas, peppers, sweet potatoes, tomatoes, white potatoes

References: Jackson et al. Nutr Res Rev. 2017.[9] ● Hord et al. Am J Clin Nutr. 2009.[10] ● Jones. Sports Med. 2014.[11]


Nicotine — cigarette smoking in particular — can reduce arousal in both men and women[12][13][14][15] For men specifically, regular cigarette smoking is a risk factor for ED[16] and may reduce fertility.[17]

Lifestyle activities that help prevent the narrowing of blood vessels all over the body, including those that supply blood to the penis, can be important for maintaining general as well as erectile health. In addition to smoking, excessive alcohol intake, lack of sleep, excessive body fat, poor mental health, and inadequate exercise can all contribute to ED.


Age is a strong predictor of ED. The condition affects 18% of men over age 20 in the United States, with roughly 45% of men over 20 and 50% of men 40–70 reporting at least some issues with ED.[2] 


The sex hormones estrogen and testosterone help orchestrate nitric oxide production in the genitals.[6][18] Low testosterone is a well-known risk factor for ED. A blood test is used to assess your levels of testosterone and its components (free T, bound T, etc.). You can learn about how testosterone is assessed here.

The path to solving your sexual dysfunction may start with addressing a root cause that’s a step or two removed from the hormonal deficiency itself, such as obesity or decreased insulin sensitivity.[19]

If you don’t know where to start, talk to an endocrinologist.

Medical conditions

Most erection problems have a contributing physical cause. Below are some common medical conditions that may play a role in ED.

  • Clogged arteries (atherosclerosis)

  • Diabetes

  • Heart or thyroid conditions

  • High blood pressure

  • Low testosterone levels, which can also reduce libido

  • Nerve damage

  • Nervous system disorders (e.g., multiple sclerosis, Parkinson’s disease)

  • Spinal cord injury

Mental health and relationship problems can also contribute to ED. Depression, stress, and anxiety all play a role.


Phosphodiesterase type 5 inhibitors (PDE-5) inhibitors, such as sildenafil (Viagra, Revatio), are the main pharmaceutical agent used to treat ED.[20] However, headaches, indigestion, abdominal pain, and flushing are commonly reported adverse effects of the drug.[20] 

Unusually long-lasting erections, called priapism, may also occur. If an erection lasts 4 hours or longer, contact a health care professional immediately.

Other common oral drug treatments include:

Keep in mind that these are intended to cause erections only when you are aroused. The effect of the drugs typically occurs in 15–45 minutes and can last for several hours.

Other ED medications include drugs that are injected into the penis or tablets that can be placed into the opening of the penis (e.g., alprostadil urogenital (Caverject, Caverject Impulse, Edex, Muse)). With this treatment, an erection may occur within 5–20 minutes (depending on which delivery method is used) and last 30–60 minutes.

If you have heart disease, discuss the use of these drugs with your physician. Some ED drugs are also contraindicated for men who take nitrates.

Furthermore, these drugs don’t work for some people,[21] so there’s room for other possible therapies to improve ED.

Some drugs may cause erectile problems as well, notably:

  • Antidepressants

  • Cocaine

  • Blood pressure medicines (particularly beta-blockers)

  • Heart medicines (e.g., digoxin)

  • Sleeping pills

  • Some peptic ulcer medicines

A comprehensive list of drugs that may cause erection problems can be viewed here.

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Human Effect Matrix

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The Human Effect Matrix looks at human studies to tell you what supplements affect Erections.

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Grade Level of Evidence
Robust research conducted with repeated double-blind clinical trials
Multiple studies where at least two are double-blind and placebo controlled
Single double-blind study or multiple cohort studies
Uncontrolled or observational studies only
Level of Evidence
? The amount of high quality evidence. The more evidence, the more we can trust the results.
Supplement Magnitude of effect
? The direction and size of the supplement's impact on each outcome. Some supplements can have an increasing effect, others have a decreasing effect, and others have no effect.
Consistency of research results
? Scientific research does not always agree. HIGH or VERY HIGH means that most of the scientific research agrees.
grade-b Minor Very High See all 4 studies
An improvement in erectile dysfunction is seen with 3g of Korean Red Ginseng (fermented panax ginseng, regular panax ginseng not as well tested) which is thought to be secondary to anti-fatigue effects and improved blood flow
grade-b Minor - See study
Erections are increased following yohimbine ingestion which is thought to be a combination of alpha-2-adrenergic antagonism (enhancing relaxation of the penile tissue so engorgement of blood can ensure) and increasing blood pressure (which would increase the amount of force in an erection). However, may not be able to overcome organic erectile dysfunction associated with poor blood flow
grade-c Minor - See study
Increased erectile function has been noted with CoQ10, but this may be secondary to reductions in symptoms of Peyronie's Disease

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Click here to see all 21 references.