Kale for Erections: What the Evidence Says

Search for foods that help with erections and kale appears in almost every list. The reasoning is usually one sentence long: kale contains nitrates, nitrates become nitric oxide, nitric oxide widens blood vessels.

Every step in that chain is real. The problem is what gets left out — that kale is a middling nitrate source, that the largest study on diet and erectile dysfunction found its effect in a different family of compounds entirely, and that the strongest number in this entire field belongs to something you do rather than something you eat.

Here is the actual evidence, with the numbers attached.

What nitric oxide actually does

An erection is a plumbing event before it is anything else. Arteries feeding the penis relax and widen, blood flows in faster than it drains out, and the pelvic floor muscles clamp down on the veins to trap it there.

Nitric oxide is the signal that starts it. It relaxes the smooth muscle in artery walls, letting the vessel open. This is not a fringe theory — it is the same pathway ED medication works on. Sildenafil does not create nitric oxide; it stops the breakdown of the messenger that nitric oxide switches on, which is why those drugs do nothing without arousal in the first place.

Your body makes nitric oxide two ways. One uses the amino acid arginine. The other converts dietary nitrate from vegetables, via bacteria on your tongue, into nitrite and then nitric oxide. That second route is why leafy greens are in the conversation at all, and it is real.

It is also why the blood flow to the penis is the thing worth optimising, rather than any single vegetable.

Where kale sits, honestly

Kale is a nitrate source. It is not a leading one.

Arugula, spinach, beetroot, Swiss chard and lettuce all carry more nitrate per serving. If the nitric-oxide pathway is your specific reason for eating greens, rocket and beetroot do more per mouthful than kale does. Kale's reputation comes from its general nutrient density — vitamin K, vitamin C, fibre — not from topping any nitrate table.

The flavonoid story is where it gets more interesting, and less flattering.

In 2016, Cassidy, Franz and Rimm published a ten-year analysis of 25,096 men in The American Journal of Clinical Nutrition, drawn from the Health Professionals Follow-up Study. They looked at flavonoid intake and the incidence of erectile dysfunction.

Total flavonoid intake showed no significant association. The relative risk was 0.96, with a confidence interval of 0.89 to 1.02 — crossing 1, meaning the result is compatible with no effect at all.

The signal was in three specific classes:

• Flavanones — RR 0.89 (95% CI 0.83–0.95). About 11% lower risk.
• Flavones — RR 0.91 (95% CI 0.85–0.97). About 9% lower.
• Anthocyanins — RR 0.91 (95% CI 0.85–0.98). About 9% lower.

Flavanones come from citrus. Anthocyanins come from berries and other deeply pigmented fruit. Kale's characteristic flavonoids are flavonols — kaempferol and quercetin — which were not among the classes that reached significance.

So the honest reading is that the study most often cited to justify eating kale for erections did not find an effect for kale's flavonoids, and found nothing for flavonoid intake overall. Harvard Health's write-up of the same paper leads with citrus and berries for exactly that reason.

Why the food lists keep getting written anyway

Because "eat this vegetable" is easier to publish than "this is a ten-year risk modifier with a confidence interval".

There is also a category error running through most of these articles. The Cassidy study measured incidence — men who did not have erectile dysfunction at the start, and whether they developed it over the following decade. That is a question about preventing a problem slowly. It is not a study about improving an erection you are unhappy with tonight, and it was never designed to answer that.

The distinction matters for what you do next. If you are 35 and want to keep things working at 55, diet is genuinely part of that, alongside not smoking, sleeping properly and keeping blood pressure down. If something has already changed, a diet adjustment is a slow lever pulled in the background while you address the actual cause.

Worth knowing too: the same study found the effect was significant only in men under 70. And there is a sharper point buried in it — erectile dysfunction shares its risk factors with heart disease almost exactly, which is why the NHS guidance on erection problems treats a new symptom as a reason for a cardiovascular check rather than a standalone complaint.

What to actually do

Take the food part seriously but proportionately, and put the effort where the evidence is strongest.

On the plate. Eat the greens — arugula and spinach ahead of kale if nitrates are the goal. Add citrus and berries, which is where the measurable flavonoid signal actually was. Three portions of citrus fruit and berries was the intake associated with the reduction. None of this requires a supplement; the whole-food evidence is stronger than the pill evidence, and erection supplements are a separate conversation with a much weaker research base.

Pair it with movement. This is the most useful single line in the Cassidy paper and the one that gets quoted least. Men with high anthocyanin and flavanone intake who were also physically active had a relative risk of 0.79 — a 21% lower risk than men who were neither. Diet and exercise together beat either alone by a clear margin.

Then train the muscle that does the trapping. Widening the arteries only helps if the blood stays put, and that job belongs to the pelvic floor. A randomised controlled trial by Dorey and colleagues, published in the British Journal of General Practice in 2004, gave men pelvic floor exercises with biofeedback for six months. At blind assessment, 40% had regained normal erectile function and a further 35.5% had improved. Around a quarter did not respond.

Those are the strongest numbers anywhere in this article, and they come from training, not eating.

If you are new to this, start with what the pelvic floor actually is, then work through kegel exercises for men. The benefits of kegels go well beyond erections — bladder control and ejaculatory control both sit on the same muscle group.

What progress looks like

Diet is a background lever. You will not notice a change in a week, and any article promising otherwise is selling something. The Cassidy findings played out across ten years.

Pelvic floor training is faster but still not fast. The Dorey trial assessed at six months, and men who responded generally noticed something in the region of three months in. Consistency does more than intensity: a short daily session beats a long weekly one, because muscle adaptation responds to frequency.

A reasonable expectation is a few months of steady work before you can judge whether it is helping. If nothing has changed after that, the cause is likely something training cannot reach — vascular, hormonal or medication-related — and that is a conversation with a doctor, not a reason to train harder.

Common questions

Is kale bad for erections, then? No. Nothing here suggests avoiding it. The point is narrower: kale is a good vegetable being credited with a specific effect the research attributes to other foods. Eat it because it is nutritious.

Does cooking destroy the nitrates? Boiling leaches a meaningful fraction into the water. Steaming, sautéing or eating greens raw retains more. This is a small effect next to whether you eat them at all.

What about beetroot juice? It is a genuinely high-nitrate option, and the sports-science literature on nitrate and blood flow is reasonably solid. The specific evidence for erectile function is thinner than the marketing suggests, but the mechanism is the same one described above.

Can I skip the exercises if my diet is good? The evidence says no. They act on different parts of the same process — one on the arteries delivering blood, the other on the muscles trapping it. The pelvic floor exercises are what the trial data supports for an existing problem.

Should I stop my medication and try this instead? No. Never stop a prescribed medication to try a dietary or exercise approach. If you want to reduce reliance on ED medication, that is a discussion with the doctor who prescribed it.

The short version

Kale is fine. It is simply not where the evidence points.

The dietary signal was in citrus and berries, worth roughly 9–11% lower ten-year risk, rising to 21% when combined with being physically active. The strongest number in the field — 40% regaining normal function — came from six months of pelvic floor training in a randomised trial.

If you were going to change one thing after reading this, change that one.