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What are lymph nodes?

 What are lymph nodes?
 

You may not know much about lymph nodes but you may well have felt one in your neck, for instance, when you’ve had a sore throat. Most people call these swollen glands rather than nodes. But lymph nodes aren’t really glands at all. They are, however, an important part of your immune system and essential for helping your body fight infections.
 
Lymph nodes are small, kidney-shaped or round structures. According to the charity Macmillan Cancer Support, some are as small as a pinhead while others are about the size of a baked bean (i), with the largest measuring around 2cm in diameter (ii).
 

Where are your lymph nodes?


We don’t know exactly how many lymph nodes are found in the human body, but experts reckon we all have at least 500 of them (ii). And while they’re distributed throughout different parts of the body there are a few areas that have clusters or chains of lymph nodes, including:
 

  • The sides of the neck (cervical lymph nodes)

  • Under the arms (axillary)

  • The chest (mediastinal)

  • The abdomen (abdominal)

  • The groin (inguinal)

 
Some of these – including the lymph nodes in your neck, armpits and groin – are close to the surface of your skin, which explains why you can sometimes feel them if they swell up. 
 

What do lymph nodes do?


Lymph nodes are made up of layers of soft tissue called a cortex housed within a tough capsule that’s surrounded and protected by fatty tissue. The cortex contains a large number of important immune system cells. But lymph nodes don’t work in isolation. They are, in fact, an essential part of the lymphatic system – a network of organs, tissues, vessels, capillaries, ducts and nodes that has many functions, the most important being:
 

  1. Protecting the body against pathogens (disease-causing micro-organisms) by activating immune cells including lymphocytes (white blood cells) and antibody-producing cells

  2. Maintaining fluid levels in the body

  3. Absorbing fats from the digestive tract

  4. Transporting waste products and abnormal or damaged cells for removal via the liver and kidneys

 

How does the lymphatic system work?


The lymphatic system transports lymph – a colourless, non-cellular, watery fluid – around the body. It collects up to two litres of excess fluids a day from body tissues – fluids that have seeped out of tiny blood capillaries into surrounding tissues – and eventually returns those fluids to the circulatory system. This helps to maintain the fluid level in your body.
 
However it also produces and releases lymphocytes and other immune cells that keep an eye on and then kill any pathogens such as bacteria, viruses, parasites and fungi that have entered your system. It has a number of components, including:
 

Lymph


Also called lymphatic fluid, this originates as fluid that has leaked from capillaries into tissues and can contain a number of things including proteins, minerals, fats, nutrients, lymphocytes as well as damaged cells, pathogens and cancer cells. Lymph that has been absorbed into the lymphatic system but hasn’t yet been passed through and filtered by a lymph node is called afferent lymph; efferent lymph is lymph that has been filtered. 
 

Lymphatic vessels


These are a network of lymphatic capillaries (points of entry for fluids from tissues being collected by the lymphatic system), collecting vessels (which transport lymph through lymph nodes) and ducts that return lymph fluid to the bloodstream. Lymphatic vessels are found in most parts of the body (though there are none in the central nervous system or bone marrow (iii)). 
 

Lymph nodes


As lymph flows through lymph nodes it is monitored for pathogens that may have entered the system. If any pathogens are found, the lymph nodes attempt to trap and kill them before they can cause any damage to the body. The lymph nodes do this by activating lymphocytes and other immune cells called macrophages that are found inside them, as well as immune cells that live elsewhere in the body. Lymph nodes also filter out any damaged cells found in the lymph, including cancer cells. Lymph enters a node via an afferent lymphatic vessel, then leaves via an efferent lymphatic vessel.
 
Also part of the lymphatic system are the following organs and tissues:
 

Spleen


This is the largest lymphatic organ and it filters and stores blood as well as produces infection-fighting immune cells. These cells help protect the body against infection by removing pathogens from the bloodstream, making antibodies and activating other parts of the immune system. The spleen is found on the left side of the body beneath the ribs and above the stomach. 
 

Bone marrow   


Found in the centre of some of the larger bones of the body, bone marrow is a soft, spongy tissue that produces a variety of blood cells from stem cells, including red blood cells, platelets and white blood cells (including lymphocytes). 
 

Thymus


The thymus is a small butterfly-shaped gland found in the chest, just above the heart and behind the breastbone. White blood cells made in the bone marrow are developed in the thymus into active – or mature – immune cells called T lymphocytes. This means they have learned to tell the difference between things that belong naturally in the body and things – pathogens, for example – that could cause harm. Once they have developed fully in the thymus, these lymphocytes circulate throughout the body via the lymphatic system and the bloodstream. T lymphocytes – which are also known as T cells – are important as they kill infected cells, activate other immune cells and help regulate the immune response.
 

Lymphoid tissue


The full term for this is mucosa-associated lymphoid tissue – or MALT for short – since the tissue is collected in the mucosa (or mucous membranes). Lymphoid tissue – which is essentially a collection of lymphocytes – is found in a variety of places in the body, including the tonsils at the back of the throat, the adenoids at the back of the nose, in the airways (bronchus-associated lymphoid tissue) and in the bowel (gut-associated lymphoid tissue), plus it’s also found in the appendix. It’s typically found in areas where toxins and pathogens may enter easily, so that the lymphocytes can try to trap and kill them before they can do any damage. 
 

Swollen lymph nodes: causes and symptoms


If your lymph nodes in one or more areas become swollen, it’s usually a sign that your immune system is fighting an infection or illness (in medical terms this is called lymphadenopathy). In simple terms, what’s happening is that your nodes are producing more immune cells, which makes the nodes expand.
 
When this happens you may notice the swollen lymph nodes feel a bit tender or even painful when you touch them. You may also experience other symptoms such as a sore throat, cough or a high temperature.
 
Common infections that can make your lymph nodes swell up include:
 
Throat infections and tonsillitis
 

 
According to the NHS, swollen lymph nodes caused by common infections should subside within two weeks (iv).
 
Less common causes of swollen lymph glands include some types of cancers. This can happen when cancer cells spread (metastasise) to lymph glands via the lymphatic system, and make the glands swell up when the cells grow and multiply. Some of these cancers include:
 

  • Breast cancer (where cells spread to the lymph gland in the armpit)

  • Throat cancer (cells spread to lymph glands in the neck)

  • Skin cancers

  • Lung and stomach cancers

 
Meanwhile cancers of the lymphatic system and blood systems – such as lymphoma and leukaemia – can also cause lymph gland swelling.
 
Very rarely, swollen lymph glands can have other causes, including certain forms of arthritis (rheumatoid arthritis, for example), HIV, systemic lupus erythematosus (SLE) and reactions to certain medicines.
 

Should you see your GP for swollen lymph nodes?


If you have a common infection that’s made your lymph nodes swell up, there’s not usually any need for treatment, and your nodes should go back to normal as soon as your body has cleared the infection. However, if any of the following apply, you should see your doctor or get professional medical advice:
 

  • Your swollen lymph nodes haven’t gone back to normal after two weeks

  • Your swollen lymph nodes are getting bigger (an inch or more in diameter)

  • You have swollen lymph nodes but no other signs or symptoms to suggest you’re fighting an infection

  • You have swollen lymph nodes that feel very painful and hard or don’t move when you press them (that is, they’re in a fixed position)

  • You have swollen lymph nodes with a very high temperature or night sweats for more than three or four days

  • Your swollen lymph nodes are just above or below your collarbone

  • The skin around the swollen lymph nodes is red and/or inflamed

 

How to keep your lymph nodes healthy


There’s no proven way to specifically keep your lymph nodes healthy, but you could argue that what’s good for your health, in general, in general is good for your immune system, and that’s good for your lymph nodes. Some suggestions for improving and maintaining good health include the following:
 

  • Eat a healthy, nutritious diet with at least five portions of fruit and vegetables every day

  • Drink plenty of water to stay hydrated (this may even help keep your lymph moving easily through your lymphatic system)

  • Stay physically active – aim for 150 minutes of moderate exercise every week, in other words take part in an activity that gets you warm and slightly out of breath (exercise may also help stimulate the flow of lymph around the lymphatic system)

  • Avoid smoking – if you need to quit, there are some helpful tips in our guide to stopping smoking 

  • Try not to drink more than a moderate amount of alcohol (this means no more than 14 units of alcohol a week on a regular basis). For tips on regulating your alcohol intake, have a look at our guide to alcohol misuse

  • Get plenty of sleep – for help with sleeping, read our guide to sleep and insomnia 

  • Make time for relaxation, as stress may have a negative effect on immunity

 

What supplements can I use for a healthy lymphatic system?


If you need extra nutritional support – if you’re not eating as healthily as you should, for instance – it may be a good idea to try a good-quality multivitamin and mineral supplement. This can help promote good all-round health, including a healthy immune system. For more information on the type of multivitamin that’s best for you, take a look at our guide to multivitamins and daily requirements.
 
There are other supplements you may find useful if your immune system needs a bit of a boost, including:
 

Vitamin D


Best known for maintaining bone health by helping the body absorb calcium, vitamin D is also thought to play a part in regulating immunity, with deficiency associated with a greater susceptibility to infection (v).

However, vitamin D deficiency is thought to be common in some countries including the UK. This is why Public Health England advises that adults and children over the age of one should consider taking a daily supplement containing 10mcg of vitamin D, particularly during autumn and winter (vi).

The recommended form of vitamin D is vitamin D3 or cholecalciferol, as it’s the natural form of vitamin D the body makes when it’s exposed to sunlight. Vitamin D3 supplements are available in tablet form, and you can get them in drops too.

However most vitamin D3 supplements are made from the fat of lamb’s wool, which means they’re unsuitable for vegans. The good news is that vegan vitamin D3 supplements sourced from lichen are now more widely available.
 

High-strength fish oils


Omega-3 fatty acids – most notably EPA and DHA, which are found in oily fish such as salmon, trout, sardines and mackerel – are widely considered helpful for general health and wellbeing, including regulating the immune system (vii).
 
If you’re a vegetarian or vegan, you can now get these beneficial omega-3 fats too by taking supplements containing marine algae rather than fish.
 

Live bacteria


The millions of micro-organisms that live in your digestive system are thought to play a key role in immune response, as well as your overall health. Acidophilus and other types of live bacteria – or probiotics as they are often called – are thought to help boost the immune system and reduce the risk of viral infections. One study has also found a combination of four different probiotic bacterial strains may help people recover more quickly from COVID-19. In this study the volunteers who took probiotics had increased antibody responses to the virus when compared to others who took a placebo (viii). Those taking the probiotics also had less severe symptoms as well as lower amounts of the virus in their bodies 15 days after they caught the virus.
 
Food sources of live bacteria include yoghurt, kefir, sauerkraut, miso and tempeh, but nutritional supplements that contain including acidophilus and other probiotics are also considered beneficial, with many people finding them a convenient way of topping up their ‘good’ gut bacteria.
 
 
A well-functioning lymphatic system and lymph nodes are essential for a healthy immune system. Even if your lymph nodes swell up, it isn’t usually a sign of anything serious – though it’s a good idea to know when you should see a health professional if this happens to you. Having a strong immune system is essential for good health, and there are lots of things you can do to keep yours in good working order. For more advice and information on a range of health and wellness issues, visit our pharmacy health library

 

 

References:

(i) Available online: https://www.macmillan.org.uk/cancer-information-and-support/worried-about-cancer/the-lymphatic-system
 
(ii) Available online: https://www.immunology.org/public-information/bitesized-immunology/organs-and-tissues/lymph-node
 
(iii) Shan Liao, Padera TP. Lymphatic Function and Immune Regulation in Health and Disease. Lymphat Res Biol. 2013 Sep; 11(3): 136–143. Available online: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3780287/
 
(iv) Available online: https://www.nhs.uk/conditions/swollen-glands/
 
(v) Aranow. C. Vitamin D and the Immune System. J Investig Med. (2011 Aug).59(6): 881–886. Available online: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3166406 Hewisom. M. Vitamin D and immune function: an overview. Proc Nutr Soc. (2012 Feb).;71(1):50-6. Available online: https://www.ncbi.nlm.nih.gov/pubmed/21849106
 
(vi) Available online: https://www.gov.uk/government/news/phe-publishes-new-advice-on-vitamin-d
 
(vii) Gutierrez S, Svahn SL, Johansson ME. Effects of Omega-3 Fatty Acids on Immune Cells. Int J Mol Sci. 2019 Oct; 20(20): 5028. Available online: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6834330/
 
(viii) Gutierrez-Castrellon P et al. Probiotic improves symptomatic and viral clearance in Covid19 outpatients: a randomized, quadruple-blinded placebo-controlled trial. Gut Microbes. Jan-Dec 2022; 14(1): 2018899. Available online: https://www.tandfonline.com/doi/full/10.1080/19490976.2021.2018899




 

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Disclaimer: The information presented by Nature's Best is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. Self-treatment is not recommended for life-threatening conditions that require medical treatment under a doctor's care. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications.

 
 
Our Author - Christine Morgan

Christine

Christine Morgan has been a freelance health and wellbeing journalist for almost 20 years, having written for numerous publications including the Daily Mirror, S Magazine, Top Sante, Healthy, Woman & Home, Zest, Allergy, Healthy Times and Pregnancy & Birth; she has also edited several titles such as Women’ Health, Shine’s Real Health & Beauty and All About Health.

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