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Your Good Health: Nitric oxide nasal spray might be effective for avoiding COVID

There are some reasons to be optimistic about this treatment
Dr. Keith Roach

Dear Dr. Roach: A doctor friend suggested I purchase a nitric oxide nasal spray from Israel. She suggested using it when eating out or hanging out with friends maskless. Do you have an opinion about its efficacy? I got the most recent booster and a flu shot. The reason I’m concerned is that I see an uptick in people around me getting COVID for either the first or second time. And I spend a lot of time with my grandchildren.


There are some reasons to be optimistic about this treatment. Two studies have shown improvement in people with COVID-19 using the nasal spray, but there are no published data I can find to show that the spray prevents infection in the first place. I did find an ongoing study in people with asymptomatic COVID-19, but the results are not yet available. Unfortunately, the kind of study needed to show effectiveness at preventing the disease is extremely large and expensive. Getting your booster, choosing wisely whether to go maskless, and avoiding large crowds remains the best way of not getting sick.

Dear Dr. Roach: Am I taking too many vitamins, and are there benefits in taking all these vitamins? I started taking fish oil for my heart; 2,000 IU of vitamin D3 was suggested by my gastroenterologist; a multi-vitamin because my mom has macular degeneration; and I started taking zinc and vitamin C because I heard it will help with COVID symptoms.


Vitamins in reasonable doses are seldom dangerous, although some can be at very high doses. Let’s take a look at each of your questions.

Fish oil has been shown to modestly improve blood pressure and cholesterol, and a prescription version reduced heart attack risk in people with high triglyceride levels in one study. In another study in people taking statins, fish oil had no additional benefit.

Vitamin D has been very controversial. Recent studies have found that vitamin D did not “prevent cancer or cardiovascular disease, prevent falls, improve cognitive function, reduce atrial fibrillation, reduce migraine frequency, decrease age-related macular degeneration or reduce knee pain.” Of course, there are some people who still benefit from vitamin D, such as people with osteoporosis, who cannot absorb vitamin D well, or who live where they never get sun exposure. The 2,000 IU you are taking is safe.

People with the dry form of macular degeneration benefit from a particular multivitamin (called the AREDS or AREDS 2 formulation) to slow progression of this condition that affects central vision. However, studies designed to show prevention of macular degeneration with the same formulation could not show a benefit. Again, though, there is no harm from these supplements, except that smokers should not take the original AREDS formulation, since they had a higher risk of lung cancer.

Multiple studies have looked to see whether vitamin C, zinc or vitamin D can prevent COVID-19 or reduce its severity; unfortunately, the preponderance of the evidence shows no convincing benefit. Taking supplements is no substitute for vaccination and prudent behaviour. Scientists have not proven that vitamin and mineral supplements benefit you for the conditions you are concerned about, but it is still possible that there is a benefit that is too small to find within the types of studies already done. The downside of these particular supplements at reasonable doses is small.

Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to