A Primer on Blood Pressure – High, Low, Dysregulated

"The brain provides nerves connecting to muscles in the blood vessel walls, telling them either to contract or relax. If this automatic control is damaged… then postural hypotension is one result." – Sarah Myhill, MD

BLOOD PRESSURE, THE CAUSES OF, AND TREATMENT

Blood pressure is necessary for blood to circulate around the body. Too little pressure causes fatigue. Low blood pressure in this country is usually a cause for congratulation by the medical profession, when for some people it makes them feel awful!

Blood pressure is created as a combination of three factors.
In order of importance:

1. Peripheral resistance - i.e. how open are the arteries [the blood vessels that carry oxygen & nutrients from the heart to the rest of the body].

2. How hard the heart is working. The heart is responsible for 60% of blood flow. The other 40% is generated by the muscular walls of arteries. Arteries pick up the pressure wave sent out from the heart and add their own booster in a wave of contraction that flows down arterial walls.

3. The blood volume, and to a lesser extent the "thickness" of the blood - if there is too much blood (as in smoking) the pressure will be high, anemia or diuretics reduce the blood volume.

Arteries can be narrowed for two reasons:

Arteriosclerosis
Firstly they may be narrowed and stiffened as a result of arteriosclerosis [stiffening, narrowing of the arteries, which when healthy are flexible and elastic]. If this is the case, then the blood pressure is fairly fixed and there is a wide pulse pressure - that is to say the difference between the top reading (systolic) and bottom reading (diastolic).

A typical reading in this case would be 170/100. Furthermore, every time it is measured it is about this level.

These are the hardest patients to treat, since all one can do is prevent deterioration by aggressively tackling the arteriosclerosis. These patients need:

• Drugs to keep their blood pressure down and prevent accelerating arteriosclerosis,
• Whilst one puts in place nutritional interventions. (See below.)

Spasm/Thickening of Arterial Muscle Walls
The second reason for arterial narrowing is spasm or thickening of the muscle walls. There are several reasons for this:

• Hypoglycemia [low blood sugar]
• Stress
• Allergies
• Mineral imbalance, especially magnesium deficiency and excess salt (sodium) in the diet
• Sleep problems - especially sleep apnea syndrome
• Hormones - particularly female sex hormones as in the Pill and HRT [hormone replacement therapy] - cause muscle thickening.

Telling the Difference

You can tell the difference between the two causes of high blood pressure [arteriosclerosis or muscle spasm] by measuring your blood pressure regularly.

• Arteriosclerosis causes a fixed blood pressure and wide pulse pressure between systolic and diastolic (e.g., 170/100) because the arteries are stiff and do not absorb the pressure wave created by the heart beating).
• Muscle spasm causes a variable blood pressure with a narrow pulse pressure between systolic and diastolic (e.g., 120/90 one day, 135/104 another).

In Practice, the Two Problems Often Co-exist…
And all the possible causes of blood pressure need tackling at the same time.

CAUSES of ARTERIAL SPASM/CONTRACTION

Hypoglycemia [low blood sugar]
This in my view is the single most important cause of high blood pressure. The problem with sugar and carbohydrates is that they are addictive. In the short term a high blood sugar brings desirable effects on the brain because:

• They allow it to work efficiently
• Whilst at the same time releasing the happy neurotransmitters that improve mood.

We all lead stressful lives and in stressful situations one needs one's brain to be working efficiently - but feeling cool calm and chilled out at the same time. To achieve this we go for our comfort foods, which nearly always are composed of carbohydrates such as chocolate, sweets, crisps, bread, bananas or whatever.

The problem with running a high blood sugar is that it is potentially damaging to muscles. The little arteries that supply blood to muscles constantly monitor levels of blood sugar and if they rise too high then these arteries will contract, thereby cutting off the blood supply to muscles, increasing the peripheral resistance and this results in high blood pressure.

At the same time, insulin is released to bring the blood sugar down - which it does by shunting sugar into fat. So the sufferer tends to gain weight easily. As the blood sugar falls, the sufferer ends up with foggy brain and inability to think clearly, combined with irritability and mood swings - and therefore goes for their comfort food again and so the cycle repeats itself.

Thus the carbohydrate addicts end up with middle-aged spread, high blood pressure, mood swings and fatigue. In the longer term these are all major risk factors for heart disease, cancer and accelerated ageing.

[See Dr. Myhill’s articles “Hypoglycemia (low blood sugar) – a problem for many chronic fatigue syndrome and fibromyalgia patients, but treatable”, and “Stoneage diet – More reasons why we all should eat it”]

Stress
Arterial muscle spasm is a normal response to stress. Homo sapiens evolved leading a very physical life fraught with danger. He had to be able to react, at a moment's notice, to physical danger. This would mean some intense physical activity - running, fighting or whatever.

To prepare for this the heart would beat faster and stronger and the arteries would narrow to "hold back" the extra blood (thereby affecting blood pressure) so that the blood could be made immediately available to wherever it was needed - usually the muscles.

So there would be a momentary rise in blood pressure - followed by a fall as the blood was utilized. These changes would be mediated by the stress hormones adrenaline, noradrenaline, and in the longer term cortisol.

The trouble nowadays is that we have plenty of stress, which causes the "fight or flight" response, but we don't burn it off. So we have high circulating levels of stress hormones which cause high blood pressure through muscle spasm. This probably explains why the "type A" personality (the aggressive go-getter) is more prone to arteriosclerosis.

The problem is compounded when the go-getter turns to sugar, fast carbs, and junk food or alcohol or smoking to help control his/her stress symptoms. A certain amount of stress is good for you. It is a case of getting the balance right.

Allergies
Allergies to foods and chemicals can certainly cause arterial muscle spasm. Indeed, this is the mechanism by which allergies cause migraine. Allergies to foods can also cause the heart to go faster and in some cases palpitations.

Mineral Imbalance
Magnesium is necessary for muscles to relax. So a deficiency will cause arterial muscle spasm with consequent rise in blood pressure.

Calcium probably also has a lesser role. It has been known for years that drinking hard water (rich in calcium and magnesium) is protective against the development of heart disease.

Salt (sodium chloride) has long been recognized as a cause of high blood pressure. The trouble is that the food industry loves to add salt to food - firstly because it disguises poor quality food, and secondly because it makes you thirsty so you then need to buy an expensive drink - wonderful for profits!

MAKING THE BLOOD PRESSURE DIAGNOSIS

Measure it. I would want to see at least 3 readings consistently high before treating. You can leave this to your doctor. The only problem is that some people suffer from "white coat" hypertension, i.e., the stress of going to see their doctor puts their blood pressure up. [See “Need blood pressure checked? You may want to sit down for this news.”]

The other possibility is to measure it yourself. There are now many excellent idiot proof blood pressure cuffs on the market.

Rare Causes of High Blood Pressure [and Tests]

These should always be considered at the first sign of high blood pressure, but in practice they are often overlooked because they are uncommon causes. However, especially if your blood pressure does not respond to treatment, then they should be reconsidered as causes:

• Any kidney disease - check for with Multistix [one brand of the over-the-counter reagent strips used to screen for multiple urine chemistry indicators – any positive findings to be investigated by a physician].



• Overactive thyroid – thyrotoxicosis or hyperthyroidism - diagnosed by blood test for thyroid hormones. [Thyroid profile testing: free T3, free T4, and thyroid-stimulating hormone (TSH)]



• Overactive adrenal gland as a result of a tumor (phaeochromocytoma). Suspect this if there are recurrent odd attacks of flushing, sweating, anxiety, headache and/or palpitations. May be misdiagnosed as a panic attack. Test for by doing urinary VMA [vanillylmandelic acid test, measures for evidence of hormone substances that such a tumor would secrete].



• Overactive adrenal gland as a result of autoimmunity - Cushing's syndrome. Check for by doing blood cortisol level.



• Overactive adrenal gland causing Conn's syndrome (very, very rare!) - low blood potassium levels. This test does not last in the post so you would have to travel to a laboratory to get the blood done.



• Poor blood supply to the kidneys - renal artery stenosis. Can present with high blood pressure. A narrow aorta causes the same problem for the same reason. These diagnoses are difficult to make - they must be suspected clinically and tested for by rapid magnetic resonance angiography. I would like to think that soon these scans should be available to make these diagnoses.



• Drugs - don't forget the Pill and hormone replacement therapy or HRT (I hate them both!), and monoamine oxidase inhibitors in conjunction with the wrong foods. [Individuals taking an MAOI, the longest-used antidepressant type, need to restrict tyramine-containing foods including many cheeses, pickled foods, chocolates, certain meats, beer and wine, and more.]



• Pregnancy - See “Pre-eclampsia” – high blood pressure during pregnancy.

LOW BLOOD PRESSURE AND POSTURAL HYPOTENSION

During evolution, a stage arrived when monkeys and apes decided to stand up. They also liked hanging upside down in trees. This presented a terrible problem for the circulation because unless the blood pressure was kept constant in all departments, some would get too much blood, some too little.

The only way this could be done was by allowing the brain to control blood supply by providing nerves connecting to muscles in blood vessel walls telling them either to contract or relax. Contracting would reduce blood supply, relaxing would increase. So when the ape stood up suddenly, the arteries to the leg and gut would contract a bit, the arteries to the head and arms would relax a bit. If this did not happen, the ape would fall over in a dead faint as blood followed gravity and pooled in the legs.

Control of blood pressure is done without us having to think about it - thank goodness! This automatic control is carried out by the autonomic nervous system. If the autonomic nervous system is damaged by pesticides, chemicals, free radicals or nutrient deficiencies then postural hypotension is one result.

Symptoms of Postural Hypotension
You faint if you don't sit down (or lie down) quick. If you don't actually faint, blood supply to the brain is reduced, resulting in feeling dizzy, spaced out, or not with it.

Postural hypotension usually occurs when you stand up. It is worse if you are hot, because blood is already diverted to skin, so it often happens to people getting out of bed.

There are some funny reflexes which can result in postural hypotension - for example having a pee. This may explain why some men faint in the night when nipping out for a slash.

Any drug for blood pressure could worsen a tendency to postural hypotension.

Treatment
Try to identify and avoid obvious causes - think about pesticides, chemicals, free radicals or nutrient deficiencies. Diabetics may get autonomic neuropathy.

Give your body time to adjust - don't jump up too quickly.

Work the muscles of your legs for a few seconds before standing up - this prevent blood pooling in legs as the muscles squeeze the blood out of the veins back to the heart.

I would treat postural hypotension as a sort of peripheral neuropathy, and use high dose B vitamins and possibly vitamin B12 injections to encourage the nerves to heal and repair. I would also check DHEA levels on the grounds that this encourages repair of tissues.

[Note: for a brief explanation of “Neurally-Mediated Hypotension” in ME/CFS and FM patients, and a protocol Dr. Paul Cheney, MD, has recommended, click here]

____
* Dr. Sarah Myhill, MD, is a UK-based ME/CFS/FM specialist focused on nutrition, preventive medicine, and patient education. This information is reproduced with kind permission from her educational website (DrMyhill.co.uk). R Sarah Myhill Limited, Registered in England and Wales: Reg. No. 4545198.

Note: This information has not been evaluated by the FDA and is not meant to prevent, diagnose, treat, or cure any illness, condition, or disease. It is essential that you make no decision about additions to or changes in your health support plan or regimen without first researching and discussing it in collaboration with your professional healthcare team.