In this series about high blood pressure control with lifestyle intervention we have looked at what causes high blood pressure and the extent of the problem (it is massive); we have looked at the pharmacological interventions (and there are so many, with pretty good effect if used consistently); we have looked at how exercise and activity can help to combat high blood pressure; and last week we looked at the effect of diet.

 ALSO READ : Turning the Tide – Dealing with the scourge of hypertension (Part 4)

However there are always controversies around diet, so today we want to start looking at some of the deeper issues.  We will begin with a more detailed discussion of one of the most amazing chemicals produced in the body – something that earned the three discoverers a Nobel Physiology and Medicine prize in 1998.  See the following interesting report from the New York Times

Nitric Oxide (NO) should not be confused with Nitrous Oxide (N2O) an anaesthetic gas also called laughing gas; or Nitrogen Dioxide (NO2) which is a toxic brown pollutant gas often seen over cities, especially when there is no wind.  Nitric Oxide can also be toxic in high concentrations, and is a free radical which only lasts seconds before being denatured.  But those few seconds allow it to have dramatic effects on the muscles of the blood vessels as it readily traversed the membranes of the endothelium (the ultra-smooth lining of the vasculature) into the muscle cells below.  In a sense, the healthy endothelium cells, through the influence of the autonomic nervous system which innervates each endothelial and muscle cell, controls blood pressure.  It is able to respond to physiological needs – such as exercise or stress, or temperature variations, etc.  Interestingly Viagra, used to counteract male impotence, works by blocking the breakdown of Nitric Oxide, allowing higher levels of Nitric Oxide in penile blood vessels resulting in more effective erections.

Interestingly, the white cells of the body use NO to kill bacterial they ingest, and thus form an important part of the defence mechanism of the body.  However in auto-immune diseases like rheumatoid arthritis, the body produces too much NO and this results in damage to the joints.

Another condition in which excessive NO is produced is septicaemia (generalised infection in the blood stream) which results in septic shock characterised by dangerously low blood pressure.

All this reminds us how incredibly complex human physiology is with so many thousands of interacting chemical reactions taking place in each cell every day.  The potential for cell destruction is constantly there, yet mechanisms come in to play to protect and modulate those reactions to ensure health and normal function of each cell.  We are incredibly designed.  The idea that this all came about by random chance is naïve in the extreme.

Here is an article about a blood test to measure endothelial function and predict the risk of all kinds of cardiovascular complications. We learn from this test about the balance between the production of nitric oxide by an enzyme nitric oxide synthase and an inhibitor called asymmetrical dimethyl arginine (ADMA).  This chemical inhibits the production of nitric oxide, and results in vasoconstriction.  One way to reduce this inhibition is by taking in extra amounts of L-arginine, a protein amino acid.

It is possible to obtain L-arginine powder as a supplement, but excessive processed supplements may have unwanted side effects.  Good sources of L-arginine are found in foods like pumpkin seeds, chick-peas, soybeans and lentils.  Even higher levels are found in turkey, chicken, dairy and pork loin, but these animal foods come with numerous negative effects like high levels of cholesterol, inflammatory chemicals, etc.  The blood test to measure the balance between production and inhibition of nitric oxide is called an ADMA test but is not yet readily available in South Africa.

Certain lifestyle practices and medical conditions are associated with endothelial dysfunction.  Smoking is a common toxin to the endothelium.  Medical conditions like obesity, high blood pressure, high blood cholesterol, diabetes and erectile dysfunction are all associated with endothelial dysfunction.

What are some foods that can boost production of NO through higher levels of L-arginine, apart from the ones mentioned above?

Spinach, kale, bok-choy, rocket, swiss chard, chicory, lettuce,

Raw cauliflower, kohlrabi, cabbage, broccoli

Beetroot

Watermelon, and spanspek

Nuts, particularly pine nuts

Whole grains – like oats

Garlic and onions.

Asparagus, celery, watercress, eggplant, potatoes, strawberries, tomatoes

Low levels are also found in bananas, green beans, sweet potatoes, cherries, chick-peas

Here is an excellent graphic and summary of the whole story about NO and heart disease:   You even get a recipe for an interesting raw beet and kale salad.

Another way to increase NO production is to boost the enzyme that makes NO, called endothelial nitric oxide synthase (eNOS).  Common foods that do this are apples and grapes.  It has been shown that these foods can boost exercise duration.

Polyphenols, of which there are many, are found in plant foods and have multiple beneficiary functions.  So go for the fresh fruit, vegetables of all different colours and types, some nuts and seeds and you will be getting all that you need for endothelial health, and cut way back on the animal products and especially saturated fats.  Here is an interesting article by Dr Joel Kahn, a plant-based cardiologist who gets amazing results treating his patients through lifestyle.

In our next article we will be discussing the role of oils in vascular health.  There is so much controversy around whether we should be on a high-fat or low fat diet; what the optimal levels of fat in our diet are; good and bad fats, and whether olive oil is this wonder health food that is the secret of long life.

I hope you have had a positive Christmas experience and that you are looking forward to a healthy year ahead.

Dave Glass

Dr David Glass graduated from UCT in 1975. He spent the next 12 years working at a mission hospital in Lesotho, where much of his work involved health education and interventions to improve health, aside from the normal busy clinical work of an under-resourced mission hospital.

He returned to UCT in 1990 to specialise in obstetrics/gynaecology and then moved to the South Coast where he had the privilege of, amongst other things, ushering 7000 babies into the world. He no longer delivers babies but is still very clinically active in gynaecology.

An old passion, preventive health care, has now replaced the obstetrics side of his work. He is eager to share insights he has gathered over the years on how to prevent and reverse so many of the modern scourges of lifestyle – obesity, diabetes, ischaemic heart disease, high blood pressure, arthritis, common cancers, etc.

He is a family man, with a supportive wife, and two grown children, and four beautiful grandchildren. His hobbies include walking, cycling, vegetable gardening, bird-watching, travelling and writing. He is active in community health outreach and deeply involved in church activities. He enjoys teaching and sharing information.

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