When most people think about controlling blood pressure, they think about reducing salt, losing weight, or taking medication. These are all valid approaches — but there is a deeper, more fundamental mechanism that is rarely discussed in routine medical appointments, and it may be one of the most direct levers available for natural blood pressure control.
Blood vessel relaxation.
The walls of your blood vessels are lined with smooth muscle cells that can either contract — narrowing the vessel and increasing pressure — or relax — widening the vessel and reducing pressure. The state of these muscle cells at any given moment is one of the primary determinants of your blood pressure reading. And the remarkable thing is that food, movement, and lifestyle choices have a direct and measurable influence on whether your blood vessels are in a state of constriction or relaxation.
Dr. Terry Shintani has identified five natural approaches to promoting blood vessel relaxation — each backed by solid clinical evidence and each consistent with the broader Peace Diet philosophy of addressing root causes rather than masking symptoms.
1. Eat More Foods That Produce Nitric Oxide — Greens and Beets
Nitric oxide is one of the most important molecules in cardiovascular health. It is a natural signaling molecule produced in the cells lining blood vessel walls — called endothelial cells — that directly signals the smooth muscle cells in those walls to relax and dilate. When nitric oxide production is adequate, blood vessels remain flexible and open. When it is insufficient, vessels constrict and blood pressure rises.
The good news is that certain foods dramatically support the body’s nitric oxide production. Leafy green vegetables — spinach, arugula, kale, Swiss chard, and particularly beetroot — are exceptionally rich in dietary nitrates. When consumed, these nitrates are converted by beneficial bacteria in the mouth and gut into nitric oxide, directly triggering the relaxation of blood vessel walls.
Research has consistently shown that diets high in nitrate-rich vegetables produce meaningful reductions in blood pressure. Beetroot juice in particular has been shown in multiple clinical trials to reduce systolic blood pressure by an average of 4-10 points within hours of consumption — a result comparable to some low-dose pharmaceutical interventions.
Practical additions to the diet: raw spinach in salads, steamed beet greens, roasted beets, arugula as a base for grain bowls, and dark leafy greens added to soups and stir-fries.
2. Eat More Magnesium-Rich Foods
Magnesium is one of the most versatile and important minerals in the human body — and one of the most commonly deficient in people eating a modern Western diet. Its role in blood pressure control is particularly significant because it works through two complementary mechanisms.
First, magnesium acts as a natural calcium channel blocker. Calcium channel blockers are a major class of pharmaceutical blood pressure medications — they work by preventing calcium from entering the smooth muscle cells of blood vessel walls, which would otherwise cause those cells to contract. Magnesium does the same thing naturally, competing with calcium at these cellular entry points and promoting muscle relaxation in blood vessel walls.
Second, magnesium is essential for the production of nitric oxide — working synergistically with the dietary nitrates from greens and beets described above. Without adequate magnesium, even a diet rich in nitrate-containing vegetables cannot produce optimal levels of nitric oxide.
Foods rich in magnesium include dark leafy greens (particularly spinach), legumes, nuts and seeds (especially pumpkin seeds, almonds, and cashews), whole grains, avocado, and dark chocolate. The Peace Diet’s emphasis on whole, plant-centered foods naturally provides far more magnesium than the standard American diet — which is one of the reasons plant-based eaters consistently show lower rates of hypertension in population studies.
3. Eat Less Red Meat, Egg Yolks, and Dairy
This recommendation addresses a less well-known but increasingly important mechanism of blood vessel constriction — one that Dr. Shintani has been aware of for years and that mainstream cardiovascular research is now confirming.
When red meat, egg yolks, and certain dairy products are digested, gut bacteria metabolize a compound called choline and carnitine — found abundantly in these foods — into a molecule called trimethylamine (TMA). This TMA is then converted by the liver into trimethylamine N-oxide, or TMAO.
Elevated TMAO levels in the blood have been strongly associated with blood vessel dysfunction — specifically, reduced ability of blood vessel walls to relax and dilate in response to nitric oxide signals. In other words, TMAO impairs the very mechanism that greens, beets, and magnesium are trying to support. High TMAO levels have also been linked to accelerated atherosclerosis and increased cardiovascular risk in multiple large population studies.
Reducing consumption of red meat, egg yolks, and full-fat dairy — the primary dietary sources of TMAO precursors — therefore directly supports blood vessel flexibility and relaxation. This is one more reason why the Peace Diet’s plant-centered approach produces such consistent improvements in blood pressure and cardiovascular health.
4. Exercise Regularly
Physical activity is one of the most powerful natural vasodilators available. When you exercise, your muscles demand more oxygen and nutrients, signaling the body to increase blood flow. In response, the endothelial cells lining blood vessel walls produce more nitric oxide — causing vessels to dilate and blood pressure to drop during and after exercise.
But the benefits of regular exercise extend beyond the workout itself. Consistent physical activity over time improves what is called endothelial function — the ability of blood vessel walls to produce nitric oxide and respond to relaxation signals. People who exercise regularly have more flexible, more responsive blood vessels than sedentary individuals — and this translates to lower resting blood pressure and better cardiovascular resilience overall.
The type of exercise matters less than the consistency. Walking, swimming, cycling, dancing, gardening — any form of sustained movement supports blood vessel health. Dr. Shintani himself has long maintained a daily basketball practice — a habit he credits with keeping his cardiovascular system sharp well into his 70s.
Even a 10-minute walk after meals — as discussed in an earlier article — produces measurable improvements in blood vessel function and blood pressure in the hours that follow.
5. Use Herbal Supplements
Certain herbal supplements have demonstrated specific abilities to support blood vessel relaxation and blood pressure control — complementing the dietary and lifestyle approaches above.
Dr. Shintani’s previous posts have covered ten supplements for blood pressure control in detail — including CoQ10, beet extract, magnesium supplements, hawthorn, and hibiscus tea. Hawthorn in particular is worth highlighting in the context of blood vessel relaxation — its flavonoids directly improve the function of endothelial cells and have been shown to enhance nitric oxide production, working synergistically with the dietary approaches described above.
Hibiscus tea — which acts as a natural ACE inhibitor — also directly supports blood vessel relaxation by blocking the hormonal pathway that would otherwise cause vessels to constrict. Three cups of hibiscus tea daily has been shown in clinical research to produce meaningful reductions in blood pressure in pre-hypertensive and mildly hypertensive adults.
As always, discuss any supplements with your physician before starting — particularly if you are already on blood pressure medication, as some supplements can interact with pharmaceutical treatments and may require dosage adjustments.
Putting It All Together
These five approaches — eating nitric oxide-producing foods, maximizing magnesium intake, reducing TMAO-producing animal foods, exercising consistently, and using targeted herbal supplements — all work through the same fundamental mechanism: keeping blood vessel walls relaxed, flexible, and responsive.
They are not independent interventions to be applied one at a time. They work synergistically — each reinforcing the others. A diet rich in greens and beets provides nitrates; adequate magnesium converts those nitrates into nitric oxide efficiently; reduced TMAO means blood vessels can actually respond to those nitric oxide signals; exercise amplifies nitric oxide production further; and targeted supplements fill any remaining gaps.
Together, they address the root cause of elevated blood pressure — not by forcing the cardiovascular system into submission with medication, but by restoring the conditions under which it naturally functions well.
Your blood vessels were designed to be flexible and relaxed. Give them what they need, and they will be.
Dr. Terry Shintani is a Harvard-trained physician (MD, JD, MPH), a Living Treasure of Hawai’i, and the creator of the Waianae Diet and the Peace Diet. He continues to see patients at his Honolulu practice and shares daily health insights on YouTube.
🌿 Learn more at PeaceDiet.org | Watch the video: https://www.youtube.com/watch?v=c9wMwAXkckI
📖 Also read:
— 9 Ways to Help Control Blood Pressure: https://drshintani.com/wordpress/2026/06/30/9-ways-to-help-control-blood-pressure-by-reducing-hardening-of-the-arteries/
— 5 Natural Supplements for Blood Pressure: https://drshintani.com/wordpress/2026/07/06/got-high-blood-pressure-5-natural-supplements-that-may-help/



















