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Have you ever wondered why too much salt can cause high blood pressure? Wanted to know what a normal cholesterol level was? Or maybe you've questioned just how healthy a home-made Chinese stir fry really is? These were just a couple of the things asked in our recent live health chat with Dr Martin Bell.

The chat kicked off at 2pm on Monday 12 September and recognised the beginning of the blood pressure testing campaign Know Your Numbers Week - with several people asking questions about getting tested.

Dr Martin Bell was also asked about a range of other topics, from those about the recommended sugar intake, to queries about ways to get more iron into the diet without red meat.

So whether you took part, asked a question on the blog in advance, or would just like to browse the questions and answers - here is a rundown of our full health chat.

Fiona1: Hi, could you explain why salt is bad for blood pressure levels? I try to avoid too much of it, but I'm not sure why it's so unhealthy.

Dr._Martin_Bell: That is a good question. Salt is bad for blood pressure because it has an effect to slightly fluid retain and as a result it causes slight increases in blood pressure levels. Therefore it is sensible to keep your salt intake to less than 6 grams a day particularly if you already suffer from high blood pressure. I hope that answers your question.

Laura: Hi Dr Bell, is high blood pressure hereditary? Both my Grandmother and Grandad have it, should I be concerned? Is there any tell tale signs I should be aware of?

Dr._Martin_Bell: Hello Laura. Yes blood pressure is hereditary, in other words if you have one or two close relatives with hypertension then you are more likely to develop it yourself. However, it is not a 100% thing i.e it is not inevitable, it all depends on the genes and whether or not you inherit this tendency. You mention your grandparents but not your parents. If your parents don't have high blood pressure you may also avoid it. As for tell tale signs, the problem is that high blood pressure doesn't tend to give any tell tale signs unless it is very high. That is a problem because it tends to silently fur up the arteries of your body so every adult should have their blood pressure checked at least every 5 years and more often if they have a family history or if a reading is found to be high.

A question from one of our blog readers, Sharron: Hello Dr Bell. How often should you get your blood pressure checked. I have no idea what mine is and cannot remember the last time I got this checked. Should my GP automatically offer this when I see him or only if I feel unwell. It seems to me that if you feel healthy, aren't overweight and exercise regularly, then you wouldn't even think about your blood pressure.

Dr._Martin_Bell: Hello Sharron, that is an excellent point. 'Healthy' people do tend to miss out on blood pressure checks and although GPs do try to remember to check the blood pressure of most people, time constraints mean that often it is overlooked. However, in my surgery we have a blood pressure machine in the reception area which anyone can use and which is very easy to use. Also blood pressure machines are very inexpensive these days so you could buy your own or share it with family or friends.

Jim: Hi Dr. Bell - do you have any particular dietary tips to reduce high blood pressure?

Dr._Martin_Bell: Hello Jim, the main dietary tips are very simple ones. Basically it comes down to reducing portion sizes to maintain a healthy weight to avoid obesity and keeping your salt intake to less than 6 grams a day (which is harder than you might think because a lot of food has high levels of salt such as take away food and salted nuts etc).

A question from one of our blog readers, Barry O'Connor: Please define blood pressure readings. Are they 'resting' blood pressure and what is resting? What about the recent NICE statement that up to 25% of people being treated for raised BP should not be? Is ambulatory BP taken over a 24 hour period the only answer and which figure is the key (ie the mean over 24 hours or the highest/lowest or what?)? I know what my BP was yesterday but does that help? What is raised BP?

Dr._Martin_Bell: Blood pressure readings are two numbers, the top one is called the systolic which is the blood pressure when the heart is contracting and the bottom one is the diastolic which is the blood pressure when the heart is filling up. Normally it refers to resting blood pressure which is defined as the person sitting quietly after a few minutes of rest.

Ambulatory blood pressure usually means taken hourly during the day and every two hours overnight for 24 hours. The other way of obtaining the same information is to buy your own blood pressure machine which is very inexpensive these days and taking your blood pressure perhaps twice a day for a few days and showing the readings to your doctor or nurse. I personally am not surprised about the NICE findings because I think most people's blood pressure goes up in the doctor's surgery so more and more I use the patient's own readings.

martpr72: How bad is cooking fresh Chinese stir fries for your blood pressure? I don't use any pre-packaged spices or sauces, but a lot of chillies, soy, light sesame oil, etc. And only use groundnut oil (approx 1 tablespoon).

Dr._Martin_Bell: Hi Martpr72, cooking fresh Chinese food is not really a problem and a lot better than eating Chinese take-aways which are renowned for being stacked with sodium from monosodium glutamate. However, just be mindful of the amount of salt in soy sauce etc, it will be written on the bottle how much sodium is in the sauces.

tobyml: Hi Dr Bell, if both my grandfathers had strokes, and my father has a history of high blood pressure, what can I do to avoid this problem or see if I've inherited it too, as it is obviously something in the family line?

Dr._Martin_Bell: Hi Tobyml, that is a good question. The best thing you can do is have your blood pressure checked regularly, perhaps once a year, because, as I mention earlier, high blood pressure tends not to give any symptoms until it is too late and causes a stroke or heart attack. The best thing is to have regular blood pressure checks because you are at higher risk than average of developing hypertension. Obviously you would be mad to smoke because this is the single most important risk factor for strokes and heart attacks and it would be wise to have your cholesterol checked as this can be an inherited factor as well.

Kristy: Is it possible to have increased blood pressure due to introduction of a new computer system in the workplace.  If so, how can this be overcome?

Dr._Martin_Bell: Hi Kristy, no it's really not possible to develop high blood pressure from a new computer at work, however stress does increase blood pressure slightly so everyone needs to de stress in some way or other with regular exercise etc

Kim: My partner seems to have a constant need for sugar. He has been checked for diabetes and is fine but i am concerned about the amount of sugar he craves. Is there a maximum daily intake of sugar?

Dr._Martin_Bell: Hi Kim, contrary to popular belief a craving for sugar rarely indicates diabetes. It is more likely to be a comfort eating type thing, There is no actual maximum sugar intake apart from the fact that it is stacked with calories so is likely to cause unhealthy weight gain and is also likely to increase the cholesterol slightly so this will increase his risk of heart disease. it comes down to everything in moderation just like you mother probably told you. I suggest you get him to see a dietician for independent advice about his diet.

A question from one of our blog readers, David Lee: I check my bp monthly, I am 67 years young and exercise 6 days a week- 1-2 hours a day. Developed bad shoulder pain-so bad that my personal trainer is threatening not to train me till I get it sorted-any ideas please? Am 5ft 7″-weight 75 kgs- used to weigh 95kgs-fight to try to get down to 70kgs so my BMI is sensible.

Dr._Martin_Bell: Hello, at 67 doing exercise 6 days a week for 1-2 hours a day probably puts you in the top 5% of fit older people so be thankful and pleased with yourself! Doing your blood pressure monthly is a good idea although it is now unlikely to ever up to very high levels because you would have developed hypertension by now if you were going to. however, i would never discourage a regular monitoring of blood pressure.

If your shoulder is a problem then try to keep up with some form of exercise which doesn't involve your shoulder such as cycling or treadmill work. Also you are wise to keep your weight down. Well done David.

NickB101: Hi Dr Bell, I sometimes suffer a lot from having shaky hands and visited my doctor a year or so ago and I had to take a couple of test's. He got the results and thought it's most likely because I have really low iron levels in my blood. He gave me the obvious advice of eating more red meat but I'm not really a fan of it. Could you suggest some other alternatives?

Dr._Martin_Bell: Hi Nick. Iron is contained in red meat but it is also in most if not all green vegetables and is often added to bread these days. Spinach in particular has a lot of iron so eating green veg should help your iron levels. Alternatively it would be reasonable to buy some over the counter iron supplements just for a while and then ask your GP to re check your blood count.

A question from one of our blog readers, Heather Atkinson: I have had my cholesterol level checked this week and it is 6.4. Although I think this is considered high, as I have had this reading for the past 6 years at least, the doctor seems quite happy. Do you think I should be doing anything to lower this more? I already use flora pro-activ, drink less than 1% fat milk and am careful not to eat too much saturated fat.

Dr._Martin_Bell: Hi Heather, this is a very common situation because your cholesterol level is largely determined by inheritance. Most of your cholesterol is manufactured in your liver and the amount is an individual thing so diet can only play a part in reducing cholesterol. It sounds like you are already doing some very sensible things, the other thing would be to make sure your weight is normal because, although cholesterol levels as such are not linked to weight (in other words a skinny person can have high cholesterol) it is true to say that your own individual level tracks your weight i.e. if your weight comes down then probably so will your cholesterol.

As regards a cholesterol of 6, this is higher than average but if you are otherwise well (not a smoker or diabetic or with known heart disease etc) then your doctor is probably right not to put you on tablets. These days it is possible for your doctor to work out your heart disease risk according to your sex, age, cholesterol, blood pressure etc and that can be a more scientific way of working out if you need to go onto medication.

A question from one of our blog readers, Jan Halliwell: My bp is always high at drs surgery or hosp appts mainly the systolic. I have bp machine at home and it is on the low side. I refuse now to have my bp taken at appts and take my bp monitor with me to show readings during the day. My cholesterol is 4.8 good (approx.8 )bad (2,6 )and bmi of 21 - am I in good heart health,.. I have a crease in my right ear and have read that could be a sign of heart disease, I have a permanent pacemaker for Wenkerbach phenomonem and is there for back up and in all annual checks less than 1% used or had to kick in!!

Dr._Martin_Bell: Hi Jan, I have never heard of a crease in the ear being a sign of heart disease so just to reassure you on that one. Otherwise it sounds like you are doing everything necessary to look after your heart and yourself. As it happens I agree with your approach to your blood pressure, I think most people's blood pressure is artificially high in the hospital or GP surgery setting so my personal belief is to continue to take your home readings with you to your appointments.

katieb: At what age should you start paying attention to your cholesterol and blood pressure?

Dr._Martin_Bell: Hi Katie. That is a very good question. The short answer is when you become an adult. High blood pressure is very rare in children, although it does occur sometimes, and raised cholesterol levels have to be very high to affect the arteries of a child. However, if someone has a family history of very high cholesterol levels then they perhaps should consider having it checked in childhood and the same goes for blood pressure if the family history is particularly bad with regard to heart disease or high blood pressure.

katieb: Hi Dr Martin, thanks for the response.  I sometimes get my blood pressure checked but my GP has never mentioned cholesterol to me.  I'm definitely an adult - should I ask them about it next time, and what kind of thing should I ask them about?

Dr._Martin_Bell: Hi again Katie, It would be sensible to have your blood cholesterol measured at least once to get a measure of what it is. If it is in the normal range then it is unlikely to change unless your diet changes dramatically.

Fiona1: Hi again, I'm reading all the answers, really interesting. Could you explain the BMI a little more to me? I try to keep my weight down, but when I check my BMI the highest healthy weight seems far too high.

Dr._Martin_Bell: Hi Fiona, pleased you are finding this useful. The BMI is your weight (in kilograms) divided by the square of your height in meters (in other words your height multiplied by your height again.) It is not a totally accurate measure but is used to assess if someone is overweight, obese etc. However it is only a tool because if someone is particularly muscular then because muscle weighs more than fat then their BMI can be high even though they are actually very healthy. As long as your BMI is between 20 and 25 then you are in the healthy range. Remember it is only a guide.

Ian: Hi - I rarely (if ever) put salt on anything, but I do eat a fair amount of processed foods. Am I likely to be consuming more than the recommended amount of salt? If so, what's the best way to cut down?

Dr._Martin_Bell: Hi Ian, yes you are very likely to be consuming more than 6 grams of salt a day. The best way to cut down is either to cook your own food, or if this is not possible in your busy life then choose processed food which is low salt. On the side of the packets of food you will be given the salt content (or the sodium content which you need to multiply by two) or these days there are sometimes low salt options.

A question from one of our blog readers, Paul Lewis: Hi, I'd like to know more about blood sugar - sometimes I can feel that my blood sugar level is very low and I have to eat to start feeling normal again. I don't know if this is normal, or should I get tested for diabetes?

Dr._Martin_Bell: Hi Paul, this is a good question but a very common misconception. Diabetes is a condition which results in HIGH blood sugar, the only connection with low blood sugar being that diabetics on insulin can have too much which results in their blood sugar being too low because of the treatment, not the condition. Your feelings of low sugar are more common in thinner people, with little in the way of energy reserve, and is a common feeling which almost certainly means nothing. However, if in doubt I would see your own doctor for advice.

A question from one of our blog readers, Malcolm Brown: Dear Dr Bell, what causes high blood pressure and why is it so important?

Dr._Martin_Bell: Hi Malcolm, as it happens we still don't know what causes most cases of Hypertension which is called "essential hypertension" and which accounts for 90% of those with high blood pressure. What we do know is that it has a hereditary factor and is made worse by such things as being overweight and eating a lot of salt.

The reason it is so important is that it is one of the most if not the most important cause of strokes and heart attacks and the problem is that it usually gives no symptoms.

ng: Hi there, last time my blood pressure was taken it was really low.  The nurse asked if I was very sporty or very laid back.  I am neither, what could this mean?

Dr._Martin_Bell: Hi Ng, low blood pressure really only means that you are lucky enough to have 'inherited' a tendency to low instead of high blood pressure. This means that you are probably at reduced risk of heart attack or stroke in later life. The only down side really is that you are more likely to feel faint in certain situations.

smellycat: Hello there, I also was interested in low blood pressure.  I am half French and there it is seen as a more serious condition than here.  Why is this?

Dr._Martin_Bell: Hi smellycat, interesting name and interesting question! Low blood pressure really isn't a serious condition in someone who is otherwise well i.e. has not had a serious accident or has another serious condition. If you are talking about people who, when they check their blood pressure, notice it to be on the low side of normal then they are just lucky to have a lower than average risk of furring up of their arteries. As I mentioned, the only down side is a slight increase in risk of feeling faint in certain situation like when you stand up from bending down etc.

GeorgieP: What is a normal blood pressure level?

Dr._Martin_Bell: Hi, Georgie. In some ways this is simple to answer but in other ways not so simple. The quoted 'normal' blood pressure for an adult is around 120/80 but of course the blood pressure varies from one person to another and one moment to another. Another way of answering that question is to say that if your blood pressure is reliably less than 140/90 then you don't have high blood pressure.

Brian: Hi Dr. Bell - is there any reliable way to measure your blood pressure at home? I was also wondering if there are any recommended non prescription medications?

Dr._Martin_Bell: Hi Brian, yes there is a very simple and reliable way of measuring your blood pressure at home; by buying a blood pressure machine of your own. They are now very inexpensive (less than £10 in some pharmacies) and easy to use and accurate. I am a great believer in home blood pressure readings and increasingly rely on my patients to check their own blood pressure. It really isn't rocket science and is really no different to a diabetic being 'trusted' to check their blood sugar, only more simple really.

There are no reliable NON prescription medications for reducing blood pressure. Reducing salt intake and your weight have been shown to help but there are no known alternative ways of reliably treating hypertension. Taking exercise can also help

Vickie_M: Hi, does Warfarin affect your blood pressure? I've been prescribed it for 6 months due to a blood clot but does it lower your blood pressure too?

Dr._Martin_Bell: Hi Vickie, Warfarin should not affect your blood pressure either one way or the other. It doesn't lower your blood pressure but obviously in you it is important to thin your blood and prevent another blood clot from forming.

Jane: Hi Dr. Bell.  I am 4 months pregnant and in very good health - I do a lot of exercise, like swimming, and I eat fairly well.  In spite of this I am still worried about staying well throughout my pregnancy.  In particular I read that pre-eclampsia can hit anyone, even very fit women.  Is there a way I can reduce the risks?

Dr._Martin_Bell: Hi Jane, what a good question and congratulations on the pregnancy and your attitude to it. You are right that pre eclampsia can affect anyone although it is more common for some reason in very young mothers and in first pregnancies for some reason. It is also meant to be more common in spring babies although I don't know if there is any proof for this. Pre eclampsia is more likely to occur in a mother who already has high blood pressure and another sign that it may occur is in a woman who has had high blood pressure whenever she has been on the combined oral contraceptive pill because the hormones in this pill seem to have a similar effect in susceptible women.

The best way to reduce the risk is to remain healthy as you are doing by eating sensibly and doint exercise but the most important thing is to attend your ante natal checks for regular blood pressure monitoring. One of the reasons why ante natal care is responsible for a dramatic fall in the maternal and baby mortality rate when it was introduced many years ago was the early detection of pre eclampsia so that it could be treated before it caused problems for the mother or baby.

jrog: Hi Dr Bell. I get a lot of headaches, and a couple of friends have suggested it could be related to my blood pressure. Could this be the case?

Dr._Martin_Bell: Hi Jrog, yes it could be the case so it would be sensible to have your blood pressure checked. However, it is unlikely that this is the cause partly because blood pressure has to be very high usually to cause headaches (which is one of the problems with it since it can exist without any signs) and the other is that there are many causes of headaches such as stress, tension, migraines, etc

A question from one of our blog readers, Rachel: I've been told that I have low blood pressure on a couple of occasions and I go through periods of feeling light headed when I stand up etc. Luckily though, I have never passed out. I'm generally fit and healthy, and try to exercise a couple of times a week. During exercise where I am pushing myself hard, I can feel very light headed. Is there anything I can do to improve my low blood pressure so I don't get this light headedness?

Dr._Martin_Bell: Hi Rachel, believe it or not it is actually harder to increase your blood pressure than reduce it. Part of the reason your blood pressure is low is that you are fit and healthy although mainly it is genetically determined. One thing which may help is to eat a normal daily intake of salt, in other words not to restrict your salt intake too much. You should aim for about 6 grams a day but preferably no more than that. Salt increases the blood pressure slightly so this may help you. Also remember that you are lucky to have low blood pressure because you are at lower than normal risk of stroke and heart attacks.

A question from one of our blog readers, Karen: Dear Dr Bell, I was reading this week that body index is not as important as it originally was thought to be, is this so, or do we still have to be aware of our index, I have always had a body index of around 23/24 which given that I run, and eat healthy is considered high, also I am not over weight. What are your views?

Dr._Martin_Bell: Hi Karen, the Body Mass Index or BMI should only be used as an indicator of your weight and whether or not it is too much or too little for your height. The reason for this is that it is not always accurate. For instance, because muscle tissue weighs more than fat, a muscular person may have a high BMI but in fact be a normal healthy person. So I think it is good to be aware of your BMI but just use it as an indicator rather than the be all and end all of weight monitoring.

A question from one of our blog readers, Teresa: I'm 41 and in good health. My blood pressure is normally higher than the recommended levels - averages around 150/100, the bottom figure is sometimes over 100. My cholesterol, BMI and body fat are all fine and I'm a non smoker. I see the GP from time to time to keep a check on my blood pressure, but they are not concerned as all other health factors are fine. Is there anything I can do to help lower my blood pressure, I do already exercise? I have a family medical history of Heart Disease with family members dying young from heart disease so I want to keep a check on this and remain as healthy as possible. Many thanks

Dr._Martin_Bell: Hi Teresa. Good question. The only thing you can do to keep your blood pressure down is to make sure your salt intake is low as salt tends to increase your blood pressure. Otherwise you are doing everything else you need to do. The only thing I would say is that a diastolic level of 100 (the lower number you mention) is considered by the British Hypertension society and NICE to be a bit high and to be considered for treatment with medication so it may be worth you going onto the BHS web site and then possibly asking your GP's opinion again. He or she may have good reasons for not treating you but it would be worth double checking particularly in the light of your family history.

A question from one of our blog readers, Kimberly: Hello who set the guidelines for BMI and how was it put together? I am a UK average size 16 but classed as clinically obese and wondered how this works as i would not class myself as obese and think that it is detrimental to people's perception and confidence in themselves?

Dr._Martin_Bell: Hi Kimberly. That's a good question. I think they were put together from measurements of the so-called normal population and advice from experts in the area. Obesity is linked with an increased risk of certain medical conditions, particularly type 2 diabetes and studying the increase in the risk of these in relation to people's BMI results in what we should aim for in terms of weight. I can see how this might affect people's self esteem but you have to balance this against an increase in developing certain medical conditions. No one is trying to criticise you, just help you to remain well.

A question from one of our blog readers, David: Hello Dr Bell Can you tell me if BMI is a better gauge of potential health issues than waist to hip ratio or should you monitor both? I've heard that waist to hip ratio is more relevant. Thank you.

Dr._Martin_Bell: Hi David. Another very good question. Both are important in different ways so you should monitor both. They are both indicators rather than being an exact science and increasingly doctors use a variety of methods of assessing potential health risks for each individual. There does seem to be a strong link between waist to hip ratio and the risk of heart disease, however. In fact doctors sometimes refer to Pear-shaped people being at less risk than Apple shaped people who have what is more technically known as central obesity around the waist. This seems to be quite strongly linked to heart disease risk.

A question from one of our blog readers, Rebecca : How do I work out my BMI?

Dr._Martin_Bell: Hi Rebecca. Your BMI is your weight in kilograms divided by the square of your height in metres (i.e. your height in metres multiplied by your height in metres). However, it is far easier to go onto the internet and search for a BMI calculator and put your height and weight in! Normal is between 20 and 25 as you probably know.

A question from one of our blog readers, Laura: What are the best ways to identify high blood pressure?

Dr._Martin_Bell: Hi Laura. Really the only way to identify high blood pressure is to have it measured or measure it yourself with a simple blood pressure monitor that you can buy from pharmacists. Because high blood pressure rarely gives any symptoms you can't rely on feeling unwell to identify high blood pressure. It is generally advised that all adults should have their blood pressure measured at least every 5 years and more often if they have a family history or have been told that they should have more frequent measurements due to a previous high reading.

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