Many of you will have gone to the GP and had your blood pressure measured. You may have been told that you blood pressure is 120 over 80 or 135 over 90, but what do these number actually mean?
When your heart beats it forces blood out in to the arteries, which produces the first number in a BP reading. This number should be 120mmHg, which is considered normal, any higher than 140mmHg would be considered bad, conversely if that number is too low it can also be bad. However if the arteries were not strong or did not produce some resistance against the pressure of the blood being pumped out by the heart, the arteries would rip open. This resistance produced by the arteries is the second number in a BP reading. This number should be 80mmHg, which is considered normal, any higher that 90mmHg would be considered bad, conversely if that number is too low it can also be bad.
From scientific research we can make estimations about your life expectancy based on your blood pressure, as you can see the higher your blood pressure the shorter your life expectancy.
• BP of 130/90 = 67 ½ years
• BP of 140/95 = 62 ½ years
• BP of 150/100 = 55 years
The arteries are not just static tubes thorough which the blood flows, they are able to constrict and dilate depending on different factors such as stress, smoking and nutritional status. If a tube through which a fluid is moving narrows, the pressure in that tube increases, conversely if it widens, the pressure in the tube decreases much like what happens in arteries.
Many of you will have heard that if you are overweight or eat too much salt you will have higher blood pressure, and that to reduce blood pressure you need to reduce salt in the diet – true, but this is not the only mechanism at work here. Inflammation also plays a big role in high blood pressure.
To understand this we need to learn a little bit about vascular biology (I can see your eyes glazing over but bear with me). The arteries are lined with cells called endothelial cells that produce a host of chemicals that can constrict or dilate your arteries. One of the major vasodilators produced by endothelial cells is nitric oxide, Nitric oxide basically tells the arteries to relax and widen, which will reduce blood pressure. What we know is that C-reactive protein (CRP) that inflammatory cytokine that I talked about in yesterday’s blog post can decrease the production of nitric oxide, leading to vasoconstriction and increased blood pressure. We also know that oxidative damage and free radicals reduces nitric oxide, and that hypertensive patients have reduced antioxidants such as glutathione, superoxide dismutase, vitamin E, vitamin C, vitamin A, copper, and polyunsaturated fats.
So there you have it – inflammation causes increased blood pressure.
One thing that has been shown to reduce blood pressure is something called the DASH diet. The DASH diet is essentially a low salt, low carb diet that is higher in protein and essential fats.
• Meat poultry and oily fish 2-4 servings a day
• Vegetables 6-8 servings a day
• Fruits 4 servings a day
• Dried beans, seeds and nuts 1-2 servings a day
• Low fat dairy products 1-2 servings a day
• Cereals, grains and pasta 1-2 servings a day
• Fats and oils 4-5 servings a day (mainly unsaturated fats like olive oil, fish oil, however some saturated fat is allowable)
• Fibre – 50g a day (mix of soluble and insoluble fibre – may need to use a fibre supplement)
Again this diet is lower in inflammatory foods and higher in antioxidants much like the Mediterranean diet I wrote about yesterday: