Home HealthTopics Health Centers Reference Library Research
Join us on Facebook Join us on Facebook Share on Facebook

High Blood Pressure

Nitrates and blood pressure

08/31/2009

Question:

Dear doctor,

I have always been fascinated by how foods can affect one`s overall health and blood pressure as a consequence. Nitrates/nitrites in foods appears to be puzzling to me.

There have been some recent studies I have come across that claim that nitrates in cured meats and especially vegetables are good for overall cardiovascular health and can lower blood pressure. There are claims that vegetables like beets and spinach contain much more nitrates than cured meat. In fact if I understand correctly most vegetables have a lot more nitrates than cured meats and hence eating a diet rich in vegetables assist in the production of nitric oxide which helps with the vasodilation of our arteries etc.

However, there are now other studies that claim that these same "good nitrates" are damaging our DNA and causing illnesses like diabetes, Parkinson`s , Alzeimers amongst others.

I personally think everything in moderation is the way to one`s wellbeing but having said that I would like to know what you know about the subject matter, Nitrates are they good or bad guys.

Thanks.

Answer:

Nitric oxide is made by the endothelial cells (the inner lining) of the blood vessels.  It is an important vasodilator and is very important for vascular function, blood flow, decrease in inflammation and glucose metabolism.  If the endothelial cells are damaged, nitric oxide production is decreased, causing vascular disease, insulin resistance, atherosclerosis and possibly Parkinson's disease.

A decrease in nitric oxide can be caused by lower production by the endothelium, or faster breakdown by reactive oxygen molecules (oxidative stress).  Hypertension, diabetes, high cholesterol or high levels of free fatty acid all increase oxidative stress.

Because of their ability to reduce oxidative stress, foods rich in antioxidants improve vascular function.  Such foods include dark leafy vegetables, purple grape juice and red wine.

However, despite experimental data showing the beneficial effects of antioxidants in the diet, human studies have shown mixed results.  On reason is that nitrates in food can be converted to carcinogenic nitrites by bacteria in the gut, thereby eliminating any positive effect.

In summary, at present it appears best to follow a diet rich in fruit, vegetables, fiber and potassium, and low in preserved food, processed food, salt, sugar and saturated fat.  Avoiding smoking and regular exercise are probably more helpful than trying to further increase antioxidants or nitrates in an already healthy diet.

For more information:

Go to the High Blood Pressure health topic, where you can:

Response by:

Max C Reif, MD Max C Reif, MD
Professor of Medicine
Director of Hypertension Section
College of Medicine
University of Cincinnati