The role of the lymphatic system in fat homeostasis

The lymphatic system is a filtration system closely tied to the function of vasculature. It filters blood plasma, draining organic and inorganic waste from the blood and cleaning lymph fluid. very forthcoming topic in all health-related disciplines. Previously, the obstacle to research in this field has been the transparency of lymph, making lymphatic vessels indistinguishable without the use of fluorescent dyes. Alongside its role in immunity, the lymphatic system is believed to be implicated in fat uptake and mobilisation, meaning it may be important in maintaining the balance between fat storage and fat usage.

Structure of the Lymphatic System

The lymphatic system consists of lymph vessels, lymph nodes and blind-ended capillaries which end at the extremities of our hands and feet. Lymph fluid is circulated around the body in the lymph vessels, where it encounters lymph nodes, particularly in the groin area, neck and underarms.

The structure of the lymphatic system allows it to fulfil its primary functions: to drain and filter fluid from the blood. Its contractile walls circulate lymph fluid around the body. Eventually, the lymph reaches a dead-end at the extreme end of lymphatic capillaries, where it is circulated upwards against gravity; propelled by the contraction of the lymph vessel walls. Propelled, by contraction, lymph is drained towards lymph nodes, where it is filtered.

Fat absorption

The initial uptake of fat, specifically fatty acids and triglycerides, from partially digested food across the lining of the gut involves the lymphatic system. Fat is packaged in chylomicrons, synthesised in our gut mucosa. Chylomicrons are taken up by lymph vessels in the gut lining called lacteals, they are then transported through the lymphatic system to the capillary blood circulation. There are two main destinations of fats in this absorption route, they supply other cells and are kept in intracellular reserves, or, if it is not needed, they are transported to extracellular reserves and adipose fat energy stores.

Chylomicrons do not reach cells, they transfer their contents to high-density lipoproteins (HDL) circulating in the blood. HDL then transports triglycerides, fatty acids and cholesterol to the liver. In the liver, fat can be packaged in VLDL and LDL; which are responsible for transporting the required fat and cholesterol to our cells. Therefore, the lymphatic system is the springboard for fat absorption, transport fat to fat stores and fat usage and, as a result, effective lymphatic drainage is crucial to healthy bodily function. Without proper lymphatic drainage, transport in lymph vessels is inefficient.

For more information, refer to Fats that Heal, Fats that Kill by Udo Erasmus

Fat mobilisation

Lipids are only mobilised from extracellular reserves and adipose fat cells when ketone bodies are consumed in respiration. A sedentary lifestyle requires a lower respiration rate and, as a result, an excess of ketone bodies such as acetyl CoA begin to build up. Their only destination, if respiration rates are low, is adipose fat storage. As a result, fat mobilisation is largely controlled by movement and basal metabolic rate.

However, a key function of the lymphatic system is to collect peripheral fat. As a result, some fat can also be mobilised from surrounding organs’ fat stores during fat absorption and digestion. This suggests that correct lymphatic drainage is crucial to fat mobilisation and metabolism as exercise does not have his effect, it causes fat to be consumed, but does not have fine-tuned control over where fat is mobilised. In fact, impairment of the lymphatic system causes a dangerous accumulation of subcutaneous peripheral fat, if the lymphatic system is out of balance, this is not something that exercise alone can resolve. In fact, lymphedema is believed to be directly caused by lymph reflux. Lymphedema has been observed by endoscopy to be characterised by “wet fat”, which suggests that both fluid and fat deposition result from disrupted lymphatics.

Stimulating lymph drainage

It is important to address the average sedentary lifestyle that many of us are accustomed to, since lymphedema rates have seen a recent increase. Standing or sitting still antagonises lymphatic drainage and fluid drainage from the blood, since lymphatic drainage has to battle gravity when we stay still in these two positions. Laying down or moving stimulates lymphatic drainage, which mostly takes place at night when we are laying down and fast asleep, which is crucial to waste drainage from the blood, fat homeostasis, immunosurveilance and dendritic cell transport, this is also the primary route for waste drainage from the brain, so definitely don’t sleep on this one guys!

Poor lymphatics has also been associated with obesity and losing weight in itself may help to boost the lymphatic system.

Furthermore, stress has a link to several elements of our overall immune function, having links to reduced immune function, the gut microbiome and immunodeficiencies originating from the lymphatic system.

I have put together  a list of activities to help you stimulate your lymph drainage and a list of causes of impaired lymph drainage or lymphedema.

There are some very useful exercises in appendix A of Dr Peter Mortimer’s book, Let’s Talk Lymphedema. These can improve your lymphatic system or help treat issues with poor lymphatic drainage. The frequency of these exercises will depend on the cause of lymphatic failure, if the lymphatic system is healthy and is simply blocked, these exercises will cure the issue and allow normal lymphatic function to resume, however, if lymphatic blockage is caused by an unhealthy and broken-down lymphatic system, these exercises will work to drastically minimise the symptoms whilst further treatment is needed to reach the cause. A treatment for the cause of lymphedema and other issues with lymphatics is eagerly awaited in years to come.

Refer to Dr Peter Mortimer’s book, Let’s Talk Lymphedema for more information.