Raynaud's and Nitric Oxide: Why Your Fingers Turn White in the Cold

Written by Jeff Butterworth N.D, Specialist Naturopath. November 2026.

You reach into the freezer, or step outside on a cold morning, and within minutes your fingers turn white. Then blue. Then, as they warm, a throbbing red that can sting for half an hour.

That is Raynaud's. And after 30 years in practice, I can tell you most people who have it are simply told to wear gloves. Gloves help. But they do nothing about the reason it happens. That reason comes down to one molecule. Nitric oxide.

What is actually happening in Raynaud's

Raynaud's is a temporary spasm of the small arteries that feed the fingers and toes. Cold or stress triggers the spasm, the vessels clamp down, and blood flow to the area almost stops. That is the white phase. As the tissue uses up its oxygen it turns blue. When the vessels finally open again, blood rushes back in and the skin flushes red.

It affects far more women than men, often starts in younger adults, and can also appear later in life alongside other conditions affecting the blood vessels or connective tissue. Either way, the mechanism is the same. The vessels constrict too hard, and they do not relax when they should.

Why nitric oxide sits at the centre of it

Every blood vessel is lined with a thin layer of cells called the endothelium. Its main job is to make nitric oxide, the signal that tells the muscle in the vessel wall to relax and open up.

When you get cold, your nervous system sends the opposite signal. It tells the vessels in your hands and feet to tighten so you hold heat in your core. In a healthy person, nitric oxide acts as the counterweight. The vessels narrow, but not too far, and they open again quickly.

In Raynaud's that counterweight is missing. Researchers describe Raynaud's as recurrent spasm of the peripheral vessels combined with lower nitric oxide availability in the cold.¹ Less nitric oxide means nothing pushes back against the constriction, so the vessels clamp shut.

Think of it like a car with a heavy foot on the brake and a weak accelerator. You can keep your hands warm to ease off the brake. But the real fix is restoring the accelerator.

Medicine already uses nitric oxide for Raynaud's

This is not a fringe idea. One of the treatments used in clinical medicine for Raynaud's is nitroglycerin gel rubbed onto the fingers. Nitroglycerin releases nitric oxide directly into the tissue.

Randomised trials show it increases blood flow to the fingers and reduces how often attacks happen and how severe they are.^2,3 Two systematic reviews pooling the trials came to the same conclusion.^4,5

The catch is that the body becomes tolerant to nitroglycerin with ongoing use, so the effect fades over time.¹ Which raises the obvious question. Can you support your own nitric oxide production every day instead?

The beetroot study

In 2019 researchers at the University of Portsmouth tested exactly that.¹ They gave 23 people with Raynaud's, most of them women in their 60s, either nitrate-rich beetroot juice or a placebo version in a double-blind crossover trial, then cooled their hands and feet and measured what happened.

After two weeks of beetroot:

• Blood flow in the thumb after cooling was higher
• The lining of the blood vessels worked better
• Blood pressure came down
• Endothelin, one of the body's strongest vessel-constricting signals, fell
• Anti-inflammatory markers improved

Here is the interesting part. The beetroot with the nitrate removed also helped. That tells us it is not only the nitrate. The antioxidant compounds in beetroot protect nitric oxide once it is made, and that matters just as much. This was the first study ever to look at dietary nitrate in Raynaud's, and it points straight at the approach I use: make more nitric oxide, and protect what you make.

Why nitric oxide drops as we age

By around 40, most adults make roughly half the nitric oxide they did at 20. On top of that, a few everyday habits drain it further:

• Antiseptic mouthwash. The bacteria on your tongue convert the nitrate from vegetables into nitric oxide. Mouthwash wipes them out.
• Low vegetable intake. Leafy greens and beetroot are the main dietary source of nitrate.
• Oxidative stress and inflammation. Nitric oxide is fragile and is destroyed quickly in an inflamed body.
• Menopause. Oestrogen supports nitric oxide production, and blood vessel function declines across the menopause transition.⁶ Given how many women live with Raynaud's, this is a big one.
• Smoking and chronic stress. Both tighten vessels and lower nitric oxide.

The two pathways, and how to use both

Your body has two ways of making nitric oxide.

Pathway one: nitrate. Nitrate from foods like beetroot and rocket is converted by your mouth bacteria into nitrite, then into nitric oxide. This pathway works even when oxygen is low, which is exactly the situation in cold, constricted fingers.

Pathway two: citrulline to arginine. The endothelium makes nitric oxide from the amino acid arginine. Taking arginine directly is inefficient because much of it is broken down in the gut. Citrulline is converted to arginine in the kidneys and raises blood arginine more reliably.

Using both pathways together, and protecting the nitric oxide with antioxidants, is what gives you a steady supply rather than a short spike.

The solution: Ultimate 4

This is why I formulated Ultimate 4. One scoop a day covers both pathways and protects the result:

• L-citrulline 1,620 mg to feed the arginine pathway
• Beetroot 1,200 mg and arugula (rocket) 1,200 mg as concentrated sources of dietary nitrate, the same food used in the Raynaud's trial
• Vitamin C 600 mg, glycine, taurine and hibiscus to protect nitric oxide from oxidative stress so it stays active longer
• Magnesium taurate to support healthy muscle relaxation in the vessel wall

It is a daily foundation for healthy circulation, not a quick fix. Most people find their best results come with consistent use through the colder months, starting before winter rather than in the middle of it.

My daily protocol for cold hands and feet

1. Take Ultimate 4 every morning. Consistency is what builds your nitric oxide baseline.
2. Test, don't guess. Use a saliva nitric oxide test strip before you start and again after two to three weeks. The optimal range is 220 to 435 mg/L, with a sweet spot around 350.
3. Ditch the antiseptic mouthwash. Protect the mouth bacteria that make your nitric oxide.
4. Eat two handfuls of leafy greens a day. Rocket, spinach, beetroot and celery are rich in nitrate.
5. Hum. Humming increases nitric oxide in the nasal passages many times over. Five minutes a day with the Nitric Oxide Daily Practice audio on our site is enough.
6. Keep your core warm, not just your hands. When your core is warm, your body is far less likely to shut down blood flow to the extremities.
7. Move your hands. Swinging your arms in big circles pushes blood into the fingers and can shorten an attack.
8. Calm the stress response. Stress is the second major trigger. Slow nasal breathing with a long exhale shifts the nervous system out of constriction mode.

The bottom line

Raynaud's is not just about the cold. It is about blood vessels that tighten too hard and cannot relax. The molecule that relaxes them is nitric oxide. Medicine already proves the point with nitroglycerin, and the beetroot research shows you can support the same pathway through food every day.

Build your nitric oxide, protect it, and give your hands and feet the blood flow they are missing.

Start with Ultimate 4 here, or learn more about optimising your nitric oxide and see the full science of nitric oxide.

References

1. Shepherd AI et al. "Beet" the cold: beetroot juice supplementation improves peripheral blood flow, endothelial function, and anti-inflammatory status in individuals with Raynaud's phenomenon. Journal of Applied Physiology, 2019.
2. Chung L et al. MQX-503, a novel formulation of nitroglycerin, improves the severity of Raynaud's phenomenon: a randomized controlled trial. Arthritis & Rheumatism, 2009.
3. Hummers LK et al. Topical nitroglycerin gel in Raynaud phenomenon: a randomised controlled trial. Annals of the Rheumatic Diseases, 2013.
4. Curtiss P et al. A systematic review and meta-analysis of the effects of topical nitrates in the treatment of Raynaud's phenomenon. Journal of the American Academy of Dermatology, 2018.
5. Qiu O et al. Efficacy and safety of topical nitroglycerin ointment for Raynaud's: a systematic review. Rheumatology International, 2018.
6. Moreau KL et al. Endothelial function is impaired across the stages of the menopause transition in healthy women. Journal of Clinical Endocrinology & Metabolism, 2012.