Antioxidants are needed to protect nitric oxide. Hibiscus tea has the highest amount of antioxidants. Each morning I make a 5 cup pot with 1/3 cup hibiscus.

This is from a Healthline article:
Increase your intake of antioxidants
Nitric oxide is an unstable molecule that degrades quickly in the bloodstream, so it must be constantly replenished (16).
One way to increase its stability and limit its breakdown is by consuming antioxidants.
Antioxidants are molecules that neutralize free radicals, which contribute to the short life of nitric oxide (17Trusted Source).
These antioxidants are found in all foods but primarily those of plant origin, such as fruits, vegetables, nuts, seeds, and grains.
A few important antioxidants include:
• Vitamin C: This antioxidant helps your body form connective tissues, including skin, bones, tendons, and cartilage. It also produces brain chemicals that help nerve cells communicate (18Trusted Source).
• Vitamin E: This antioxidant protects cells from the damaging effects of free radicals, which are thought to contribute to aging and disease. It also plays an important role in keeping the immune system strong.
• Polyphenols: This category of antioxidants is associated with several health benefits, including a reduced risk of cancer and cardiovascular disease (21Trusted Source).
• Glutathione: Coined “the mother of all antioxidants,” glutathione is the main antioxidant and detoxifier of every cell in your body (22Trusted Source).

Several studies have found that ingesting nitric oxide precursors, such as nitrate or citrulline, with antioxidants maintain greater levels of nitric oxide in your body by helping reduce its breakdown.

Vegetables that are high in nitrate are also inherently high in antioxidants, which is likely why vegetables are so effective at increasing and maintaining optimal levels of nitric oxide.

Nitric oxide is an essential molecule required for overall health. As a vasodilator, nitric oxide signals the blood vessels to relax, allowing them to expand.

This effect allows blood, nutrients, and oxygen to flow freely to every part of your body. But when nitric oxide production is decreased, your health can become compromised.

Therefore, it’s important to achieve and maintain optimal levels of nitric oxide in your body.

A diet high in nitrate-rich vegetables and antioxidants or the use of supplements, such as L-arginine or L-citrulline, are beneficial ways to boost your body’s natural production of nitric oxide. Other proven strategies include limiting mouthwash and exercising regularly.
For optimal nitric oxide production, increase your intake of nitrate-rich vegetables and exercise at least 30 minutes per day.
https://www.healthline.com/nutrition/how-to-increase-nitric-oxide#supplements