Quinn on Nutrition: Supplements for high blood pressure

GW from Carmel, California, writes: "You have been very helpful in the past, so I thought I would pose another question to you. From my research online and talking with various people, I have identified several non-prescription blood pressure reducers and I wanted to get your input. They are celery seed extract, grape seed extract, L-Arginine, nitric oxide.

They are supposed to help control and reduce blood pressure that is not too high or in the danger zone. Have you heard anything about them and also, do you have any other recommendations for something that is non-prescription and is without the usual side effects that you get from the prescription meds?"

Hi Gary,

Here's what I found:

Celery seed extract comes from celery seeds. Limited small studies on humans showed that celery seed extract helped lower blood pressure in middle-aged people. One study reported an effective dose of 150 milligrams a day. I found little other data on this product. (Don't forget, you can also use celery seeds to flavor your food!)

Grape seed extract - made from the seeds of wine grapes - has been researched for its effect on blood pressure, but the results have not been clear. According to the National Center for Complementary and Integrative Medicine, "it's possible that grape seed extract might help to slightly lower blood pressure in healthy people and those with high blood pressure," particularly those who are obese or have a condition called metabolic syndrome. Caution: High doses of this supplement with vitamin C can make blood pressure worse.

Grape seed extract may also be unsafe for people with bleeding disorders or who take blood thinning medications, including warfarin and aspirin.

Arginine (L-arginine) is an amino acid that helps the body build protein. It is found in meat, poultry, fish, eggs, dairy products and legumes. If you eat a balanced diet that includes these foods, you'll get about 4-5 grams of arginine a day, say the experts at the Mayo Clinic. Arginine converts in the body to nitric oxide, which expands blood vessels to increase blood flow. That can be helpful for blood pressure.

The limited studies on arginine supplements have shown little or no effect on increased blood flow or blood pressure, however. Doses no more than 9 grams a day seem to be safe, but some people report side effects such as nausea and diarrhea, according to the National Institutes of Health Office of Dietary Supplements.

As you see, even supplements can have side effects. We just aren't as clear on what they are, since research on many of these products is often limited. Also products marketed as dietary supplements do not have to pass strict safety measures that medication drugs do. That's why you should always run these by your health provider, who knows your individual health needs.

And yes, I do have a recommendation for a non-prescription product that helps reduce blood pressure without the usual side effects. It's called the DASH diet - a well researched eating plan rich in potassium, calcium and magnesium. The right combination of these nutrients from food have been shown to lower blood pressure. Check it out at www.nhlbi.nih.gov/health-topics/dash-eating-plan.

Barbara Quinn-Intermill is a registered dietitian and certified diabetes educator affiliated with Community Hospital of the Monterey Peninsula. She is the author of "Quinn-Essential Nutrition" (Westbow Press, 2015). Email her at to [email protected].

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