This common kitchen spice can be used for a whole range of ailments when either taken internally or used externally. Reach for the mustard seeds for respiratory conditions, common cold, flu, digestive issues, achy joints and muscles, or just to warm you up.

Respiratory: The mustard oils in the seeds are an effective decongestant, indicating mustard seed for any conditions resulting in congestion in the sinuses and lungs (2). An infusion can be used to open the lungs and relieve symptoms of various respiratory problems such as coughs, cold, flu, chronic bronchitis and sinus infections (1). The mustard oils have an expectorant action, thinning mucus so it can be more easily excreted from the body (3). These actions can help to prevent an acute infection, such as the common cold from developing into further infections such as sinusitis, ear infections or pneumonia (4). The stimulation of blood flow, decongestant, and expectorant actions also make mustard seeds useful for conditions such as chronic rhinitis and allergic airway inflammation (hay fever). 

The warming effect of mustard seed makes it a useful stimulating diaphoretic (stimulates the sweat reflex), which can help to bring out or ‘break’ a fever. This supports the body’s natural processes of defence against infections. This diaphoretic action combines with the circulatory stimulation of blood flow to the periphery to support the release of heat and toxins via the sweat (5). The warming and stimulating actions can help with the chills and lethargy that accompany a bout of cold or flu (6).

An infusion can be used as a gargle for a sore throat, harnessing both the rubefacient action (dilates blood capillaries increasing circulation) and the antimicrobial properties to both soothe and heal the infection (1, 6). 

Musculoskeletal: Mustard seed can be taken internally as an infusion, or mixed into food for a warming and circulatory action that can relieve rheumatism (1). Externally, a poultice or infused oil can be applied to the surface, near the area of internal inflammation. This is effective for relief from rheumatic pain, arthritis, neuralgia (nerve pain), sciatica, gout and muscle spasms (6).  

Digestive: Mustard seeds can be used to stimulate appetite and digestion (2). As a carminative, mustard seed can help to relieve flatulence, dyspepsia and colic (7). The circulatory stimulation also increases blood supply to the digestive organs to support the breakdown and absorption of nutrients. The mucilage in the seed coat provides a mild laxative action, useful in cases of chronic constipation (6). 

Circulatory:  Mustard seed improves the peripheral circulation to the extremities, this makes it useful for those who suffer from cold hands and feet. Mustard seed oil may also support heart health and has been suggested to protect the cardiovascular system in recovery following a heart attack (8). 

Topically/Externally 

When mustard oils are applied to the skin this creates a mild irritation which causes local vasodilation of the blood vessels, drawing blood to the area. This rubefacient (counter-irritant) action can be used therapeutically to bring warmth to an area via the increased blood flow (9). The localised warming action spreads throughout the whole body, relieving chills and supporting the diaphoretic action required during a cold and flu (10, 11).

Musculoskeletal system: External applications of mustard seed are an effective therapy for chronic degenerative diseases affecting the joints and soft tissues (7, 12). Massaging an oil infused with mustard seeds can be used as a warming massage rub for achy muscles and joints, to relieve chilblains and rheumatic pain (9). Research has demonstrated that a mustard poultice or plaster applied daily can improve pain, stiffness, and physical functioning of the joints in patients with osteoarthritis (13). 

Respiratory system: Infused oils can be massaged onto the front or back of the chest, or applied as a poultice. The stimulation of blood supply to the area, as well as the absorption of the mustard oils through the skin, helps break up congestion and catarrh in the lungs, and ease a chesty cough (12). Research has demonstrated that a mustard seed plaster applied to the lungs for twenty minutes can improve symptoms in patients with chronic bronchitis, and provide long-term improvement in immune function (14). A mustard seed foot bath can also be used to relieve symptoms of an acute respiratory tract infection, such as a cold or flu (15).

Nervous system: A foot bath has warming and stress-relieving benefits, but adding mustard seed powder to the soak further enhances these benefits. A mustard seed foot bath increases energy, vitality, relaxation, stress relief and whole body warmth, all of which are related to positive health (16). This is particularly useful in chronic conditions where fatigue and low vitality are a key feature, as well as warming the whole body to relieve acute chills (11). 

Mustard is a warming stimulant suited to conditions that are energetically considered to be cold, damp and depressed (17). A cold tissue state refers to a lack of physiological vitality or lack of warmth from a poor blood perfusion to the tissues (17). This cold state is characterised by a pale complexion and cold skin and extremities. A depressed tissue state does not refer to the depressed state we think of in relation to mental health, but refers to a physiological reduced function of the tissues. This will often result in low resilience to infections (17). A system in a depressed, damp or cold state can result from excessive mucus secretions which causes a build-up of phlegm, congestion and stagnation (17). Warming of the fluids and movement of the congestion are key to restoring function to the mucus membranes and improving resilience to further infection (18). The stimulating and aromatic qualities of mustard improve tissue function by increasing the circulation and perfusion of blood, returning the warmth and vitality that is lacking in a cold and depressed tissue state (17).

Mustard seeds contain glucosinolates, specifically a constituent called sinigrin, which is broken down to produce allyl isothiocyanates (AITCs), also known as mustard oil (19). The glucosinolates in mustard are sulphur containing compounds, responsible for the hot and pungent properties, also present in horseradish, wasabi and nasturtium (18). It is these strong volatile oils which are decongestant via a mucolytic action, which thins the mucus for easier excretion (9). The mustard oils also have strong antibacterial activity (20) which can be useful in chronic infections, which often arise from mucous congestion. Volatile oils are strongly antimicrobial, and since these oils are excreted from the body via the lungs, they bring this antimicrobial action directly to where it is needed in respiratory infections (6, 9). 

Volatile oils stimulate the tissue they come into contact with, creating a slight irritation (9). This aids digestion by stimulating the lining of the digestive tract which increases the flow of digestive juices, supporting digestion and increasing the appetite (9). These same volatile oils relax the muscle wall in the lower part of the intestine, which can ease griping pains and release trapped wind (9). 

The allyl isothiocyanates and sinalbin found in mustard seeds also have antioxidant and anti-proliferative effects, which slow the growth of cancer cells, and cause apoptosis (20). This has been shown to be preventative in cancer cell development in a human trial (21), suggesting a protective effect of including mustard seeds as part of a balanced diet. Please note if one is seeking integrative oncology care then it is best to work with a specialist as treatment is nuanced and case specific.

White and black mustard seed remedies have been used since the time of Hippocrates both internally for digestive complaints and externally as a counterirritant to reduce inflammation (6). Internally, it was traditionally used to support the digestive processes and clear mucus from the lungs. Externally, it was applied as a poultice at the site of internal inflammation, such as applying to the chest in cases of pneumonia or bronchitis to break up congestion (1). 

In what would be considered today as “heroic medicine”, mustard seed was used in large doses as an emetic to provoke vomiting or purging of the digestive tract, for example in cases of snake bite or mushroom poisoning (1). A teaspoon of mustard seed powder in a cup of boiling water was also thought to relieve hiccups (1). Culpeper promoted both the internal and external use to relieve drowsiness and prevent forgetfulness, and to rub on the temples and nostrils to warm and quicken the spirits (22). He also suggested that chewing the seeds could help with a toothache (22). When applied to a hot foot bath, mustard seeds were used to dispel a cold and relieve a headache (1). It was thought that the increased circulation to the feet drew blood flow and congestion away from the head, relieving the pressure and inflammation causing the headache (7).

The mustard we use as a condiment today has a long history of use to both flavour meals and for the medicinal properties it contains. Gerard in 1623 stated that “the seede of Mustard pounded with vinegar is an excellent sauce eaten with any meates because it doth help digestion, warmeth and stomache and provoke appetite” (1).

Respiratory support

A white mustard seed plaster (poultice) was found to significantly improve chronic bronchitis compared to a control treatment (14). In the clinical trial, 59 patients with chronic bronchitis had a Tracheitis Plaster (containing mustard seed with four other ingredients) applied to the back of the lungs for twenty minutes. There was a significantly greater improvement in symptoms, X-ray chest film, and immune system function after the mustard seed plaster, compared to the control group (25 patients). The effect was still present six months and one year after the treatment (14).

Patients with an active respiratory tract infection (RTI) performed a mustard seed foot bath (three tablespoons ground black mustard seed) for seven minutes, on six consecutive days (15). The 103 patients in the intervention group were compared to 36 patients with a RTI who did not perform a foot bath. The foot bath significantly improved perception of coldness, feelings of unwellness, and feelings of exhilaration. The control group only showed a significant improvement in the unwellness scale, though this improvement was slightly less than the foot bath group (15).  

Musculoskeletal 

The effectiveness of a mustard plaster (powdered black mustard seeds) on osteoarthritic pain, stiffness, and physical joint functioning was assessed in a group of 60 elderly patients with osteoarthritis (13).  Patients were evenly randomised and assigned to the control group (no treatment) or mustard plaster, which they applied for 15–20 minutes for 14 days. There was a significant reduction in osteoarthritic scores in the mustard plaster group, and this was significantly greater than the control group. The authors concluded that the practice of mustard plaster application resulted in a reduction in osteoarthritic index among elderly (12). 

Cardiovascular support

In a randomised controlled trial (RCT), 360 patients were followed for one-year after experiencing an acute myocardial infarction (heart attack). The patients were randomly assigned to take a daily supplement of either fish oil, mustard oil (20g) or a placebo (8). Compared to the placebo condition, both the fish oil and mustard oil groups had significant improvements in their cardiovascular health. This resulted in significantly reduced cardiac events — cardiac arrhythmias, left ventricle enlargement and incidents of angina. The authors suggested that mustard oil may have a protective effect in those at risk of a heart attack, via a reduction in oxidative stress, reduced inflammation and improved blood cholesterol markers (8).

Immune support

The allyl isothiocyanates (AITCs) in mustard seeds have been shown to be preventative from cancer cell development in vitro (20). This effect has also been demonstrated in a human clinical trial of fourteen volunteers, who consumed 20g of a mustard preparation (25mg ITC) for four days (21). There was a significant decrease in two blood markers of cancer risk including DNA damage, as well as a reduction in blood cholesterol levels. The authors concluded that even short-term intake of mustard provides cancer-protective effects, and may be associated with reduced cancer risk (21). 

Whole body warmth and vitality

Research in young, healthy adults shows that a warm foot bath containing black mustard powder (80g in 12l) for 20 minutes, increased self-reported vitality (positive sense of energy and aliveness) when compared with warm water alone (16). There was also a shift in autonomic balance (measured by heart rate variability) towards relaxation, and a reduction in overall stress levels (16). Vitality is related to health, particularly of the immune and cardiovascular systems (23, 24) and is even correlated with cancer risk (25). This study supports the health promoting benefits of mustard foot baths (16)

The same research group repeated this study in patients with cancer, using a warm foot bath containing black mustard powder (80g in 12l) for 20 minutes (11). The mustard foot bath increased the warmth perception of the feet and whole body warmth for a longer duration than warm water alone (11)

A recent RCT in 2022 investigated the effect of a mustard compress (applied to the back of the chest) on local skin temperature and self-perceived whole body warmness (10). The healthy adults had a mustard compress (40g powder), ginger compress (40g powder) or warm water applied for 20 minutes (10). The mustard compress was significantly better than the other conditions at increasing the warmth of the local skin area during and after the compress removal. Both the mustard and ginger compress increased the warmth perception, meaning the whole body felt warmer during and after the compress application (10).

The seeds will germinate easily all year round, and can be grown into seedling plants to provide salad greens throughout the winter (1).

Both black mustard and white mustard are native to Europe and grow wild across the UK in fields and on roadsides (1, 27). Mustard grows throughout Asia, Northern Africa, North and South America (1). Mustard is largely cultivated throughout the world and harvested for the seed to be manufactured to condiments.

Mustard seed is currently unranked by Nature Serve, meaning the global conservation status has not yet been assessed (28). However, it is well distributed across North America, Canada, UK and Europe, and does not appear on the U.S. Endangered Species act (28), or the United Plant Savers “to watch” (29). The International Union for Conservation of Nature (IUCN) have global assessed Brassica nigra and list it as “Least Concern” (30). They state that the species is widely distributed in many parts of Europe, temperate Asia, and northern and northeast tropical Africa with stable subpopulations, and there are currently no major threats reported (30).

You can read more about sustainable sourcing of herbs here.

Heeding to the safety considerations outlined, mustard seed is a safe herb to take, though it is important to buy from a reliable source. Unreputable sources can be contaminated, adulterated or replaced with the wrong plant material. To ensure the quality of a product look out for certified organic labelling and check that the correct botanical name is used. Also, you should be able to obtain information from suppliers regarding the origin of the product ingredients, to find out where the herbs have come from. There is more opportunity for contamination and adulteration when the supply chain is unknown.

Sow the seeds in spring in holes 30cm apart. The seeds ripen at the end of the summer, when they are harvested and dried.

Homemade mustard

Ingredients:

• 50g black mustard seed
• 50g white mustard seed
• 100ml apple cider vinegar
• 1 teaspoon of honey
• 1 teaspoon turmeric powder
• 1 teaspoon of salt

Method:

• Soak the mustard seeds in the vinegar for two days, then add the rest of the ingredients and blend in a food processor until ground into a paste.
• Keep in the fridge. 

Recipe adapted from De La Foret (2017) (3).

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