DEAR DR. ROACH: In a recent column, you responded that fluoride is naturally occurring, and places that removed fluoride from drinking water had increased tooth decay. Is fluoride naturally found in well water? I’ve drunk well water my whole life, and I’ve only had one cavity. Two of my three kids are the same way. The oldest had too many antibiotics during her the teeth-forming years, so hers are awful and so are my husband’s. What about the microbiome? Does fluoride in water affect the microbiome? — D.R.

ANSWER: In an appropriately low concentration, fluoride can reduce tooth decay, but at high levels, there is potential for harm, including changes to brain development. Municipal water plants aim for a concentration near 0.7 mg/L, while tooth discoloration can happen at levels of 2.0 mg/L and fluorosis of the bones may occur in levels above 4 mg/L. Neurological effects are possible once levels exceed 1.5 mg/L.

A review by the United States Geological Survey found that 1.6% of well water was above 4 mg/L, but 85% of wells were below 0.7 mg/L. Ideally, you want to aim for enough fluoride to reduce tooth decay but not enough for toxicity, so knowing the concentration in your home is critical.

I found a number of available tests online — both home tests and send-out lab tests — for about $50. (I had some trouble finding home tests that were able to give accurate results for fluoride at these levels, so I’d recommend the send-out tests.) I also went to the Environmental Protection Agency and found out how to contact my state-certified laboratory for testing water (tinyurl.com/waterlabtest).

When I called my local lab, they seemed somewhat surprised by my question but very willing to test my water. In addition, I was easily able to find the fluoride concentration in my community water through their website.

As for your final questions, fluoridated tap water at the recommended concentrations shows no harmful significant effect on the human microbiome. One study found possible beneficial effects.

DEAR DR. ROACH: There has been much hype about beetroot powder. Even my close friends are suggesting that I take it as a general health benefit. Is there any evidence that beetroot powder is beneficial to one’s health? — Anon.

ANSWER: Beetroot, whether as a concentrate or powder, contains numerous substances with the potential to help some aspects of health. It contains several antioxidants but has mostly been looked at as a source of nitric oxide production from the nitrates that are naturally present in beets.

Athletes have used beetroot to enhance their athletic performances, but there is limited evidence to suggest that this may be beneficial. There may also be salutary effects on cholesterol and blood pressure; however, the level of evidence is not strong.

Unfortunately, anything with the potential for help always has the potential for harm. Beets are very high in oxalates, which could predispose people to kidney stones. One study found that drinking a lot of beetroot juice (or powder) could increase the body’s production of N-nitroso compounds, which are potentially carcinogenic.

While I have an open mind for the use of herbal and natural products for the treatment of symptoms, there aren’t any products that meet my criteria for the proof of benefit and the absence of harm; therefore, I can’t recommend its use in general for healthy people to enhance their health beyond what they can get from a healthy, mainly plant-based diet.

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 ToYourGoodHealth@med.cornell.edu. (c) 2025 North America Syndicate Inc. All Rights Reserved