Cinnamon supplement appears to affect glucose reading

Dear Dr. Roach: I have had slightly elevated glucose levels (104-109) for several years. I found a dietary supplement of cinnamon, vitamin D and chromium. I took the directed amount for a period of time and had a glucose test of 61. I don’t know if it was a fluke or not. A recent A1C test came in at 5.9%. I backed off that dosage and now take only half three or four times a week. My glucose has gone back up.

I have also had slightly elevated creatinine levels (1.3-1.6) in the past. This was the case before starting the cinnamon supplement. My creatinine readings have largely been stable since starting the product. Can you tell me if this product is safe and whether it could adversely affect my kidneys?

— D.P.

Cinnamon was marketed as a natural treatment for diabetes some years ago, and one analysis of studies found that it reduced the average blood sugar by about 9 points, which corresponds to roughly an A1C lowering of 0.3%, which would be enough to make your elevated level go into the normal range. Unfortunately, another review of the published studies found no benefit at all on glucose, A1C or insulin levels using cinnamon supplements.

Similarly, the evidence for chromium is suggestive, but not definitive. One review showed that chromium improved blood sugar in people with diabetes, but reviewers noted the studies were mostly poor quality. Giving more vitamin D to people who are not deficient did not help improve diabetes control.

At reasonable doses, cinnamon, chromium and vitamin D are all safe. There is no risk of kidney damage when taken as directed.

Still, a healthy diet and regular exercise are much more likely to have beneficial effects on diabetes control than a supplement.

Dear Dr. Roach: Plants apparently produce oxygen while absorbing CO2. A year ago, we moved to an apartment, and the only place we could find for a large potted ficus was in our master bedroom. Is this promoting our health while we sleep?

— ANON.

Unfortunately, the amount of oxygen a houseplant provides isn’t much. A human consumes about 500 liters of oxygen a day, while a typical houseplant might produce 20 liters a day. Given the size of an apartment, the oxygen it makes will diffuse away and not meaningfully increase the oxygen concentration in your apartment. Apartments and houses are not remotely airtight.

Worse, plants make oxygen only when they are photosynthesizing, i.e., when they are in the sun. During the night, plants respire like we do and produce CO2 and consume oxygen, although at a very low rate.

Finally, more oxygen isn’t better for humans — unless you have lung or (rarely) heart disease that requires oxygen. I remember years ago seeing athletes breathing oxygen from tanks, but this is useless in healthy people.