Thanks to Francesca Testa, medical student at Kings College, for putting this piece together. Head to the bottom of the page to find out a little more about Francesca. You can read her previous post for The Food Medic about Orthorexia here.
Do you find yourself feeling dizzy or light-headed when standing up quickly from sitting or lying down? Do you experience blurred vision and feel faint and/or sick after you have been standing for a long time?
These symptoms might be a sign of hypotension, or low blood pressure (BP), and they are much more common that you might think, especially among young women and elderly.
So, what is blood pressure?
Imagine your blood vessel-system as a set of tubes and pipes which are all connected with each other, and our blood as water passing through those pipes. Your blood pressure is the force with which your blood flows into those vessels/pipes. This force is not the same all the time, yet changes throughout the day, according to our level of activity and even our degree of stress, anxiety, and relaxation. For instance, it decreases while we are asleep, and it increases when we exercise or we are facing stressful situations.
Blood pressure is defined by two numbers: the top number is your systolic blood pressure- which describes the pressure when your heart contracts and pumps out blood, and the bottom number is your diastolic blood pressure – which indicates the pressure when your heart relaxes and fills up with blood.
A normal blood pressure in adults is usually around 120/80 mmHg. Nevertheless, when it gets below 90/60 mmHg, we talk about hypotension or low blood pressure which usually presents with feeling dizzy, light-headed and even faint. It can also be associated with blurred vision and nausea.
Is hypotension dangerous?
Low blood pressure may be a symptom of an underlying medical condition, yet it may also be experienced by perfectly healthy individuals.
If you find yourself feeling faint or dizzy, it is strongly advisable to consult your GP as soon as possible, to rule out any dangerous causes of low blood pressure. Indeed, hypotension may be a sign of a wide range of medical conditions, including heart problems, hormonal (or endocrine) imbalances and serious infections (or septicaemia). It may also present as a result of dietary deficiencies, such as insufficient intake of iron (leading to anaemia), or vitamin B12. Other conditions causing low blood pressure might be dehydration and blood loss.
As a result of the rapid expansion of the circulatory system to supply the foetus, pregnant women commonly experience a drop in blood pressure, which often returns to their pre-pregnancy level after giving birth.
Some medications (such as water pills or diuretics, some types of antidepressant known as tricyclic antidepressants, beta blockers, alpha blockers and drugs for erectile dysfunction – just to mention a few) may decrease your blood pressure as a side effect.
If you don’t have any other worrying symptoms (e.g. very fast or very slow heart beat) and medical causes of hypotension have been ruled out by your doctor, then having a low blood pressure is not something you need to be concerned about. Indeed, it is very common, especially across active and young women.
But what are the causes of low blood pressure in a healthy individual?
Fit and healthy people may experience two different types of low blood pressure: orthostatic hypotension and neurally-mediated hypotension, also known as vaso-vagal episodes or faints – let’s go through each of them.
Orthostatic hypotension occurs when you experience dizziness when standing up from a sitting or lying down position. Mild orthostatic hypotension is common and can occur briefly in anyone, although it is most common amongst the elderly and can often be the cause of falls in this population. This is simply the result of your body not adjusting your blood pressure and flow fast enough for the change in position. If you have ever experienced this, you may also notice that the light-headedness self-resolves in few seconds – that is when your blood flow has finally adjusted to the new position.
On the other hand, vaso-vagal episodes occur when the dizziness comes on after prolonged standing. When we walk or move our legs, we ensure that blood returns to heart. However, after standing still for a long time, blood starts to pool in our legs, it cannot promptly return to the heart and, as a consequence, our blood pressure drops. The symptoms of dizziness and nausea are caused by a “miscommunication” between the brain and the heart, where, instead of making the heart pumps faster, the brain encourages the heart to slow down, which causes a further decrease in blood pressure.
How do I manage my symptoms?
Orthostatic hypotension and vaso-vagal faints are not dangerous per se, yet they may put you at risk of falls. In addition, symptoms can be understandably unpleasant and even scary.
The good news is that with some small lifestyle changes you can make these episodes less distressing, as well as more and more rare.
Keep yourself well hydrated throughout the day:
We all know it is a healthy habit to carry a bottle of water with us at all times, it is even more beneficial if you tend to experience dizziness due to hypotension. Hydration ensures your blood flows nice and smooth.
Watch your alcohol and caffeine intake:
alcoholic and caffeinated beverages are both known to cause dehydration, which might eventually lead to a drop in your BP.
Research on the impact of caffeine on blood pressure has produced unclear results, with the effect being dependent on several factors, including age and the individual’s average consumption of caffeine. Nevertheless, generally speaking, caffeine seems to cause an immediate spike in blood pressure, possibly followed by a decrease due to its dehydrating effect. Some people experiencing low blood pressure symptoms may find beneficial to have a cup of coffee before engaging in physical activity, but again this is extremely variable and changes from person to person (9).
Take care when standing up:
if you find yourself feeling faint when standing up from sitting or lying down, make sure you change position slowly, giving time to your body to adjust blood pressure and flow.
Move around:
if you tend to stand for long periods of time, make sure you move your legs and go for walks, to ensure a patent circulation and avoid that unpleasant feeling of light-headedness due to a sudden drop in pressure.
Eat small meals, but often:
having small, regular meals will help stabilise your blood sugar levels without fatiguing your digestive system and compromising your blood flow.
Limit your consumption of refined carbohydrates:
Foods with a high GI index such as sugary snacks and cakes, but also refined breads and cereals, tend to be digested quickly and may cause an initial spike in your sugar levels and a consequent drop in your blood pressure, this is known as postprandial hypotension. Thanks to the longer digestion time, going for their wholegrain version might help stabilise both your blood sugar levels, and your blood pressure. (6,10)
Drink liquorice tea:
there is extensive scientific evidence that supports liquorice tea property of increasing blood pressure. Although excessive consumption of liquorice tea might lead to high blood pressure – also known as hypertension, having it in moderation may help manage your symptoms of hypotension. Up to 2 cups of liquorice tea a day has been proved to be a safe amount (2,5).
Can I exercise with a low blood pressure?
Of course you can! Indeed, long term physical activity may help stabilise your BP.
Nevertheless, if you are known to experience dizziness and fainting during exercise, it is important to take a few precautions.
Once again, keeping well hydrated is key!
Be aware of your posture: some people tend to experience dizziness in any position where the head is below the level of the heart. If this sounds familiar to you, avoid performing those exercises or opt for a safer version.
Performing aerobic exercise (aka cardio): after a high intensity- session, do not stop moving suddenly, yet make sure you cool down gradually. For instance, if you have been running, slowly decrease your speed until reaching a walking pace. Keep walking until you feel steady enough to finish your workout.
Take care when standing up from lying down or sitting.
When not associated with other medical conditions, the unpleasant dizziness and light-headedness due to hypotension can be managed with some precautions and lifestyle changes. However, if these lead to no improvements or your symptoms are troublesome, it is extremely important to report these symptoms to your doctor.
References
(1) https://www.nhs.uk/conditions/low-blood-pressure-hypotension/#causes
(2) https://www.nhlbi.nih.gov/health-topics/hypotension
(3) https://www.healthline.com/health/low-blood-pressure-diet#what-to-eat
(4) https://www.nature.com/articles/1001215
(5) https://www.nejm.org/doi/full/10.1056/NEJM199110243251706
(6) https://www.mayoclinic.org/diseases-conditions/low-blood-pressure/diagnosis-treatment/drc-20355470
(7) https://www.medicinenet.com/can_i_still_exercise_with_low_blood_pressure/ask.htm
(9) http://hyper.ahajournals.org/content/43/4/724
(10) https://www.health.harvard.edu/heart-health/eating-can-cause-low-blood-pressure
