Leafy greens: the same nitrate, working for you this time

On the watermelon page nitrate appears as a caution. Here it appears as the reason to eat the food.

Same compound, opposite framing, and the difference is dose, source and what you are trying to achieve.

What nitrate actually does

Dietary nitrate is reduced to nitrite, and nitrite to nitric oxide, particularly under the low-oxygen and acidic conditions that occur during hard exercise.

Nitric oxide widens blood vessels, improves blood flow, and increases oxygen delivery to working muscle. The downstream effects reported include improved function of type II muscle fibres, a reduced ATP cost of force production, and more efficient mitochondrial respiration.

Nitrate-containing foods and juices appear on the International Olympic Committee consensus list of supplements with potential performance benefit. That is one of a very short list of things that made it onto that document.

The benefits described include extending time to exhaustion, improving time trials under 40 minutes, enhancing type II fibre function during high-intensity work, and improving intermittent team sport activity.

That last category is the one combat sport sits closest to.

The judo study, and what it actually found

Most nitrate research is in cyclists and runners. One trial went directly at this sport.

Thirty-five male adolescent recreational judokas completed a randomised, double-blind, placebo-controlled crossover trial, taking either 140 millilitres of beetroot juice containing around 8.4 millimoles of nitrate or a placebo, with a 7-day washout.

Each session included a 4-minute randori followed by the Sargent jump test, back-strength dynamometer pulls, handgrip trials and the Special Judo Fitness Test.

That split is the useful part. The sport-specific, repeated high-intensity work improved. The single-effort strength and power measures did not.

Which is consistent with the wider literature. Nitrate helps where the demand is repeated, intermittent and oxygen-limited. It does not make you stronger or more explosive in a single attempt.

For a fighter that maps cleanly. It is a tool for the fourth round rather than for the first exchange, and for a tournament day rather than for a one-punch outcome.

The standard caveat applies: recreational adolescents rather than elite seniors. It is still considerably closer to this sport than a time trial on a bike.

The part almost nobody knows

The first step in the pathway happens in your mouth, before anything reaches the rest of the body.

How much, and from where

That beetroot range is worth noticing. It is the same variability described under watermelon: content depends on how the crop was grown, and there is no single figure for any vegetable.

The commonly cited target is 0.1 to 0.2 millimoles per kilogram of body weight. For a 70 kilogram fighter that is roughly 7 to 14 millimoles, or 434 to 868 milligrams.

Reaching that from salad means a very large quantity of leaves, which is why the research uses concentrated juice and why most practical use does too.

Two things nobody warns you about

The second is gastrointestinal. Concentrated nitrate shots have high osmolarity, and taking one on an empty stomach or in a fluid-depleted state can produce nausea, cramping and diarrhoea.

That is a bad outcome in a normal week and a serious one in fight week, which is the reason for the rule at the bottom of this page: test it in training first.

And the tension with fight week

Leafy greens carry fibre, and fibre is residue, and residue is weighed with you. The low residue phase removes them along with everything else green.

So the food that delivers the nitrate is the food that comes off the plate in the week you might most want the effect.

That tension resolves in one specific way. Beetroot juice carries the nitrate without the fibre, which makes it the version that works in the final days when spinach does not.

Juice is a poorer choice than whole vegetables almost everywhere else on this site. In this one narrow case the property that makes it worse is the property that makes it usable.

Where the leaves earn their place otherwise

Nitrate is not the main reason to eat leafy greens, and that needs saying.

Spinach, kale, rocket and lettuce are low in calories, high in volume, and carry vitamin K, folate and a spread of micronutrients a fighter in a long deficit is at risk of missing.

They are also lower in fermentable carbohydrate than the cabbage family, which makes them considerably easier on the gut than broccoli or Brussels sprouts and puts them later in the removal order rather than first.

In camp, leafy greens are a default rather than a decision. Eat them because the volume helps and the micronutrients matter, and treat the nitrate as a bonus that only becomes a strategy if you are deliberately dosing it.

Why it might not work for you

Nitrate is unusual on this site in having good evidence and a well-documented list of reasons an individual might see nothing.

Training status. Several analyses suggest the effect is smaller in highly trained endurance athletes than in recreational ones, possibly because baseline nitric oxide handling is already efficient. That cuts against the population most likely to be buying it.

Your oral microbiome. The bacterial population varies between people, and somebody with fewer nitrate-reducing bacteria converts less of what they take. Not something you can check without testing.

Diet composition. One study found a low carbohydrate, high fat diet altered the oral microbiome, though the nitrite response to beetroot juice was preserved. Worth knowing rather than acting on.

And the effect appears more consistently where oxygen availability is limited, which is part of why it shows up in hypoxia studies and in high-intensity intermittent work.

The honest summary: a real intervention with genuine individual variation, and the only way to know whether you are a responder is to test it in training with something measurable.

The oxalate point

Spinach is high in oxalate, which binds calcium and reduces its absorption from the same meal.

For most people this is irrelevant. It matters in two situations.

For a fighter relying on plant sources for calcium, spinach is a poorer calcium source than the numbers suggest, because much of what it contains is bound. Kale, which is much lower in oxalate, is the better choice for that purpose.

And for anybody with a history of calcium oxalate kidney stones, high spinach intake is a question for a doctor rather than for this page.

Cooking reduces oxalate content somewhat, and it is one of the few cases where boiling and draining has a specific nutritional argument behind it.

A note on the other greens

Frozen spinach is nutritionally comparable to fresh, considerably cheaper, and solves the problem that fresh leaves wilt within days. For a fighter buying vegetables weekly it is the more practical purchase.

Washing, and the thing that actually matters

Bagged salad has been implicated in food-borne illness outbreaks more often than most produce categories, because the leaves are handled extensively and eaten raw.

For a fighter that is a fight week consideration rather than a general one. In the last week, a bagged salad in a hotel is a risk with no upside, because the leaves are coming off the plate that week anyway.

Washing pre-washed bagged leaves again does not reliably help and can introduce contamination from your own kitchen. Buying whole heads and washing them yourself is the more reliable route if it matters to you.

Where it sits by phase

If you are going to use it properly

• Take it as beetroot juice at a measured dose rather than hoping salad covers it.
• Time it 2 to 3 hours before the effort, which is roughly when plasma nitrite peaks.
• Leave the antibacterial mouthwash alone for the period.
• Expect red urine and tell your corner, because the alternative is a panic in fight week.
• Test it in training first. Gastrointestinal tolerance varies, and a concentrated shot on an empty stomach is a bad first experience to have on a fight day.

For a tested athlete, a beetroot shot sold for athletes is a supplement product and belongs to that category with the batch-testing requirement attached. Beetroot from a shop is food.