High blood pressure - causes of
Blood pressure is necessary for blood to circulate round 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 and smaller blood vessels.
2. The output of the heart. 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. If you could see arteries working they would look like wriggly snakes!
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. Anaemia or diuretics reduce the blood volume.
Causes of high blood pressure
Arteries can be narrowed for two reasons. Firstly they may be narrowed and stiffened as a result of arteriosclerosis. If this is the case, then the blood pressure is fairly fixed and there is a wide pulse pressure reflecting stiff arteries - that is to say, the difference between the top reading (systolic) and bottom reading (diastolic) is high. A typical reading 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.
The second reason for arterial narrowing is spasm or thickening of the muscle walls. This is what happens in the early stages of high blood pressure and this is reversible. There are several reasons for this spasm:
- Stress - causing adrenaline release. Lack of sleep could do this, especially sleep apnoea syndrome. See Sleep Apnoea Syndrome
- Mineral imbalance, especially magnesium deficiency and excess salt (sodium) in the diet
- Hormones - particularly female sex hormones as in the Pill and HRT - cause muscle thickening.
You can tell the difference between the two causes of blood pressure by measuring your blood pressure regularly. Arteriosclerosis causes a fixed blood pressure and wide pulse pressure (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 (eg 120/90 one day, 135/104 another). In practice, the two problems often co-exist and all the possible causes of high blood pressure need tackling at the same time.
The problem with spasm of the arteries is it creates local high blood pressure, this increases turbulence of the blood within vessels and this damages the delicate lining of the blood vessels. Arteriosclerosis is the body's attempt to heal and repair this damage. It is essential to do this to prevent the blood vessel bursting! The healing and repair involves sticking a fibrous patch over the damage and this scar tissue slightly narrows and stiffens the artery resulting in permanent narrowing. The point here is that the reversible reasons for arterial narrowing result in the irreversible reasons for arterial narrowing! Once one has this irreversible narrowing, prescription medication is an essential part of treatment otherwise further damage caused by high blood pressure results.
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 it allows the brain 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 comprised 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 the levels 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 Hypoglycaemia and Ketogenic diet - the practical details and My book The PK Cookbook - Go Paleo-ketogenic and get the best of both worlds
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 creating 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 utilised. 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. See Exercise. So we have high circulating levels of stress hormones which cause 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 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.
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 recognised 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, secondly because it makes you thirsty so you then need to buy an expensive drink - wonderful for profits!
Blood pressure is largely controlled by the kidneys - they do this partly because they must secure a good energy supply for themselves! The kidneys consume a lot of energy and are highly dependent and sensitive to regular good energy supply - if this falters the kindey fails. To prevent this they will increase the blood pressure via hormones renin and angiotensin to secure a sure energy supply. Anything that compromises mitochondrial function therefore will impact on the kidneys and their response to this could result in high blood pressure. See CFS - The Central Cause: Mitochondrial Failure. Indeed many drugs used to control blood pressure inhibit these hormones.
Another issue has to do with heavy metals. The kidneys are a favourite dumping ground for heavy metals. This may cause problems for two possibly reasons - firstly direct toxicity by inhibiting mitochondria. Secondly heavy metals may act as haptens to switch on allergy and/or auto-immunity. This results in useless inflammation which gets in the way of normal renal function. The glomerular filtration rate will slow - an early sign of kidney disease. See Toxic metals - a problem for us all.
Making the diagnosis of high blood pressure
Measure it. I would want to see at least 3 readings consistently high before diagnosing high blood pressure. You could leave this to your doctor. The only problem is that some people suffer from "white coat" hypertension, ie the stress of going to see their doctor puts their blood pressure up. The other possibility is to measure it yourself. There are now many excellent idiot proof blood pressure cuffs on the market and this is the best solution. It also helps you to identify situations where your blood pressure peaks - so, for example, you would be more likely to pick up an allergy problem (often allergic reactions are accompanied by an increase in pulse rate and this would also raise blood pressure).
In the early stages of raised blood pressure it is possible to correct the problem with nutritional interventions. In the late stage, when the arteries are stiff with arteriosclerosis, the nutritional inputs will do no harm but may not reduce blood pressure. At this stage one is in a vicious cycle of impaired blood supply to the kidneys resulting in a release of hormones that increase blood pressure (in an attempt to increase renal perfusion). This causes further damage to blood vessels! So late stage high blood pressure, especially when accompanied by kidney disease, does require medication.
The problem is that most doctors treat all cases of blood pressure as if they were late stage problems, thus committing many people to lifelong medication when, in fact, simple nutritional interventions would do the trick. Again early hypertension is a warning sign that not all is well!
Rare causes of high blood pressure
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 urine testing.
- Overactive thyroid - diagnosed by blood test for thyroid hormones.
- Overactive adrenal gland as a result of a tumour (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.
- 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 cannot be done on a sample sent to the lab 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 HRT (I hate them both!), monoamine oxidase inhibitors in conjunction with the wrong foods.
- Pregnancy - Pre-eclampsia.
- Arteriosclerosis - what causes it and how to prevent it
- Sleep Apnoea Syndrome
- CFS - The Central Cause: Mitochondrial Failure
- Toxic metals - a problem for us all
- Ketogenic diet - the practical details
- My book The PK Cookbook - Go Paleo-ketogenic and get the best of both worlds
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