Beta blockers are pharmaceuticals used to manage abnormal heart rhythms, and to prevent heart attacks. In this article we highlight how they work, and discuss plants that support heart health.
Beta-blockers are used to dampen down the effect of stress and nervous tension on the heart and circulation, for example to steady the heart and reduce high blood pressure.
There is no herb that does the same job but some have similar effects. One may be able to use such herbs to head off a beta blocker prescription.
With the cooperation of the prescriber, and where there is no imminent health threat of cardiovascular disease, it is also possible to use such herbs alongside or even instead of a prescription, especially if beta blockers are found not to have been as helpful as hoped and now that doubts have been cast on their long-term benefits.
Stress detection
Adrenaline (epinephrine) and noradrenaline (norepinephrine) are two hormones released in response to danger or exertion by the body’s sympathetic (‘fight-flight’) nervous system. Adrenaline is pumped into the bloodstream from the core of the adrenal glands.
A more sophisticated response is the release of noradrenaline from the ends of sympathetic nerve fibres where these attach themselves to other cells. Because the effect of noradrenaline is directly on the target tissue it is referred to as a ‘neurotransmitter’.
Neurotransmitter effects on cells and tissues are mediated by receptors: proteins that span the cell membrane and behave rather like ‘locks’ into which the neurotransmitter ‘keys’ fit. The receptors in this case are called ‘adrenergic receptors’ or adrenoreceptors and are set up so that when the noradrenaline is detected they activate chemical messengers within the cell and switch on various functions.
There are two groups of adrenoreceptors, alpha (α) and beta (β). They have broad ranges of effects around the body. However most medical interest is in their effects on the circulation.
- α1 receptors lead to vasoconstriction (narrowing of the blood vessels) and stimulation of other visceral muscle. As these receptors predominate in the tissues the main action of noradrenaline is therefore to raise blood pressure.
- α2 receptors counteract the α1 receptors as an inbuilt control mechanism.
- β1 receptors increase heart rate and stroke volume (ie the amount of blood pumped at each stroke), and also increase secretion of the hormone renin from the kidney; all these factors work together also to raise blood pressure.
- β2 receptors are vasodilatory and are the predominant receptors in the coronary blood vessels. They tend to relax smooth muscle around the body, notably opening the airways, and slow down gut motility. β2 receptors are the most sensitive to low levels of noradrenaline and so predominate in non-stressed situations.
Beta-blockers
These medicines block β receptors. They slow the heart, improve the conduction of electrical signals in the heart, relax blood vessels, and lower blood pressure.
More than a dozen beta blockers fall into three main groups.
- Nonselective: The earliest beta blockers, like propranolol, affect both β1 and β2 receptors. They should be used with caution, if at all, in smokers or people with asthma or other lung conditions because by blocking β2 they can constrict the airways.
- Cardioselective: A number of beta blockers, including atenolol (Tenormin), bisoprolol (Cardicor or Emcor), and metoprolol (Toprol, Lopressor) were designed to block only β1 receptors in heart cells. Since they don’t affect β2 receptors in blood vessels and the lungs, cardioselective beta blockers are safer for people with lung disorders.
- Third-generation: Some β blockers such as Labetalol (Normodyne, Trandate) also block α receptors. This further helps relax blood vessels. Nebivolol (Bystolic) also stimulates the inner lining of blood vessels (the endothelium) to generate nitric oxide, which helps the vessels relax. Carvedilol (Coreg) does both.
Beta blockers may be used to treat:
- Angina: Chest pain caused by narrowing of the arteries supplying the heart
- Heart failure: Failure of the heart to pump enough blood around the body
- Atrial fibrillation: Irregular heartbeat
- Heart attack: An emergency where the blood supply to the heart is suddenly blocked
- High blood pressure: However now used when other hypotensive medicines have been tried, or in addition to them (see below).
Less commonly, beta blockers are used to prevent migraine, to treat an overactive thyroid (hyperthyroidism), or to manage anxiety.
Concerns about beta blockers
Beta blockers are very widely prescribed with few or mild side effects, occasionally including feeling tired, dizziness or lightheadedness, cold fingers or toes, difficulties sleeping, nightmares or feeling sick. More rarely there may be shortness of breath with wheezing or a cough that gets worse on exercise.
However in spite of the theoretical case for blocking β1 receptors, these agents have proven not to be as effective as hoped, and they are rarely prescribed alone for hypertension. There are also increasing doubts about the long-term value of beta-blockers. A large study published in The Journal of the American Medical Association found that beta blockers did not prolong the lives of patients. The researchers followed almost 45,000 heart patients over three-and-a-half years and found that beta blockers did not reduce the risk of heart attacks, deaths from heart attacks, or stroke (1). A separate study published in the same year found the same (2). It appears that any short term symptomatic benefits beta blockers provide do not translate into the long term.
There are now well-attested risks that beta blockers could contribute to dangerous stroke and heart attacks if given at too high a level when there is a risk of low blood pressure, e.g immediately after surgery.
There are some medicines that may interfere with the way that beta blockers work.
- other medicines for high blood pressure. The combination with beta blockers can sometimes lower your blood pressure too much. This may make you feel dizzy or faint
- other medicines for an irregular heartbeat such as amiodarone or flecainide
- other medicines that can lower your blood pressure. These include some antidepressants, nitrates (for chest pain), baclofen (a muscle relaxant), medicines for an enlarged prostate gland like tamsulosin, or Parkinson’s disease medicines such as levodopa
- medicines for asthma or chronic obstructive pulmonary disease (COPD)
- medicines for diabetes, particularly insulin – beta blockers may make it more difficult to recognise the warning signs of low blood sugar
- medicines to treat nose or sinus congestion, or other cold remedies (including those you can buy in the pharmacy)
- medicines for allergies, such as ephedrine, noradrenaline or adrenaline
- non-steroidal anti-inflammatory medicines (NSAIDs), such as ibuprofen. These medicines may increase your blood pressure, so it’s best to keep them to a minimum
Herbs that may be helpful
There is no known herbal equivalent to beta-blocking activity. Moreover although there may be doubts about beta blockers, interfering in a prescription can be dangerous: the problem here could be a precarious cardiovascular condition with attendant risks of coronary attacks, stroke or thrombosis. Rather than take unilateral action it is important to talk with prescribers. Reducing or stopping beta blockers might be acceptable especially if they have been prescribed for broader stress-related symptoms. It may also be possible safely to complement their activity and even render their continued prescription less necessary.
The following plant remedies (including three consumed as foods) step up as ones to consider in this context.
Hawthorn (Crataegus spp.)
This herb is probably closest to beta blockers in its effects, although its mechanisms are different, involving the combined vasodilatory effects of polyphenols (including for coronary circulation) and cardiac calming effects of procyanidins. This is a practitioners’ favourite for the management of heart and coronary symptoms, especially when associated with anxiety, tightness in the chest, and palpitations. Mild angina, intermittent episodes of tachycardia (fast heartbeat), benign arrhythmia (irregular heartbeat), and high blood pressure are among the symptoms that appear to respond to this remedy. The flowers and berries have similar actions, but the berries are thought to be more useful in the lowering of blood pressure and the flowers at improving circulation to the peripheries. It combines well with motherwort for anxiety-related heart symptoms and, for more general tonic effects, with lime or linden flowers (see below).
Motherwort (Leonurus cardiac)
This herb is associated with calming anxiety symptoms, especially in the chest, with a focus on reducing tension in the diaphragm and is a great herbal accompaniment to breathing exercise. As its botanical name suggests there was an association with reducing palpitations, most often a direct symptom of tension in the diaphragm and ribcage (with the creation of a resonating chamber to amplify heartbeats).
Gotu kola (Centella asiatica)
A classic rejuvenative tonic (rasayana) from Ayurvedic tradition, gotu kola has particular reputation for protecting the nervous system from excess stress, trauma or illness. It also improves the integrity of blood vessel walls and thereby improves circulation to key tissues. These and other properties mean that this remedy can often feature in supporting conditions that might call for a beta blocker prescription.
Lemon balm (Melissa officinalis)
This common garden herb is a relaxant remedy that has been useful when stress affects the chest and heart, with symptoms like palpitations and hyperventilation. These in turn may be associated with diaphragm tension linked for example to acid reflux and hiatus hernia, where lemon balm’s other benefits on digestive problems may have additional relevance.
Ginkgo (Ginkgo biloba)
This modern herbal remedy has always been seen to improve peripheral circulatory problems including symptoms of atherosclerosis, and to reduce the risk of cardiovascular disease. The extract has also been shown to reduce impacts of stress, anxiety and depression. Note however that all the evidence for ginkgo is for a highly concentrated patented extract of the leaves and that there is no such evidence or tradition for the leaves themselves.
Limeflowers (Tilia spp.)
The flowering bracts of the lime or linden tree have long been used to calm the nerves and relax the blood vessels. It improves the peripheral circulation and helps to lower blood pressure.
Skullcap (Scutellaria lateriflora)
This relaxing remedy has also been applied where stress and nervous tension are associated with palpitations and high blood pressure.
The following foods can be used to support the circulation as part of a long-term strategy for many conditions for which beta blockers are prescribed. There will be no problems in using these alongside any prescription.
Beetroot (Beta vulgaris)
A food item with significant benefits for the circulation, it contains nitrates that are converted into vasodilatory nitric oxide in the body. Recent research has confirmed that this improves tissue blood flow and lowers blood pressure.
Green tea (Camellia sinensis)
The most popular drink in the world also has appreciable long-term benefits in protecting the circulation. A key part of its benefits are linked to its observed effects on improving the health and integrity of the lining of the blood vessels, the endothelium. It is at this surface that almost all inflammatory processes commence and ‘endothelial dysfunction’ has been implicated in a wide range of inflammatory diseases, cardiovascular problems, dementia and diabetes.
Bilberry (Vaccinium myrtillus)
Like its more common food relative blueberries contain high levels of vasodilatory blue pigments (anthocyanidins) that have established benefits for fragility of the veins and peripheral circulation. It can be tried for poor peripheral circulation, including for complications of diabetes and high blood pressure.
Ayurvedic herbs include Sarpagandha (Rauwolfia serpentina) and Arjuna (Terminalia arjuna). TCM uses pattern treatments so formulations like Tian Ma Gou Teng Yin for Liver Yang Rising , and Long Dan Xie Gan Tang (Liver Fire) are very popular.
References
- Bangalore S, Steg G, Deedwania P, et al. (2012) β-Blocker Use and Clinical Outcomes in Stable Outpatients With and Without Coronary Artery Disease. JAMA. 308(13): 1340–1349. doi:10.1001/jama.2012.12559
- Zuckerman IH, Yin X, Rattinger GB, et al. (2012) Effect of exposure to evidence-based pharmacotherapy on outcomes after acute myocardial infarction in older adults. J Am Geriatr Soc. 60(10): 1854-61. doi: 10.1111/j.1532-5415.2012.04165.x.
