CBD oil may help alleviate pain from sickle cell anemia and supports red blood cell production. Check out the top CBD oils for anemia. The main biological activities of cannabis are due to the presence of several compounds known as cannabinoids. Delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) are two of the main cannabinoids. Studies have shown that the effects of THC can be modulated by CBD. This study aims to look at the effect of different concentrations of THC and CBD separately and in combination, on blood viscosity, elasticity and membrane integrity. Blood samples were collected from twenty-four healthy adult non-smokers. Blood viscosity and elasticity were determined using the Vilastic Scientific Bioprofiler for different concentrations (0, 2.5, 25, 50 and 100 ng/ml) of CBD and THC respectively, as well as in extracts with combinations of CBD and THC in 4:1 and 1:1 ratios respectively. Repeated measures analysis of variance (ANOVA) was used to determine the difference between the means of the groups. Blood viscosity increased significantly with increasing concentrations of both THC and CBD from 25 ng/ml up to 100 ng/ml ranging from 6.45 ± 0.36 mPa·s to 11.60 ± 1.12 mPa·s for THC and ranging from 5.46 ± 0.24 mPa·s to 9.91 ± 1.10 mPa·s for CBD respectively, being more pronounced in the extracts at 21.33 ± 2.17 mPa·s for the 4THC:1CBD extract and 21.76 ± 1.88 mPa·s for the 1THC:1CBD extract. There was no significant increase in elasticity for THC and CBD separately. However, a significant increase in elasticity was observed in the extracts. THC and CBD affected red cell morphology resulting in complete disintegration at the highest concentrations. THC and CBD increased red blood cell viscosity and elasticity separately and in combination. They also adversely affected membrane integrity.
CBD & Sickle Cell Anemia Pain: What the Research Says
Sickle cell anemia is a type of anemia that involves misshaped blood cells.
This condition can be very painful — here’s how CBD may be able to help.
Anemia is a common medical condition involving loss, premature breakdown, or dysfunctional manufacture of red blood cells.
It basically means we don’t have enough high-quality blood in our veins and arteries.
There are many different types of anemia, each with its own set of treatment options, and symptoms.
Some people have begun taking CBD oil as a treatment for their anemia.
Here, we discuss what types of anemia CBD oil can be used for, how it works, and when CBD oil doesn’t work for this condition.
MEDICALLY REVIEWED BY
Updated on November 14, 2021
Table of Contents
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The Benefits of CBD Oil For Sickle Cell Anemia
CBD oil is useful for many things, but it mainly works by supporting homeostasis in the body — which can be defined as a “state of balance”.
In the case of anemia, there are only a few ways that CBD oil can help; and the people with sickle cell anemia will have the most to benefit from it.
This is because one of the primary side effects of the condition is pain and inflammation as the misshapen red blood cells that get lodged in the tiny capillaries of the cardiovascular system. When this happens, it blocks blood flow from the area, causing the cells to starve for oxygen and nutrients.
This is a significant source of pain for these individuals, often prompting them to take opioids or other pharmaceutical pain medications.
CBD directly inhibits the pain associated with sickle cell anemia, and can dramatically improve the quality of life for these patients.
The benefits of CBD oil for anemia include:
- Alleviates pain from sickle cell anemia
- May support the production of red blood cells
- Supports energy levels in patients with iron-deficient anemia
Anemia: Red Blood Cells & Their Impact On Our Health
One of the most underrated cells in the body is the humble red blood cell.
They are made in the bone marrow before being released into circulation and are responsible for carrying oxygen from the lungs to every other cell in the body – and then bringing some of the CO2 produced in the organs back to the lungs for elimination.
These specialized cells are vital to our health and wellbeing. Any issues with them can leave our cells suffocating for fresh oxygen. This leaves us feeling weak, tired, pale in complexion, and lowers our ability to resist cold and flu.
This is the main problem with anemia.
When we’re anemic, it means that our red blood cells are either misshapen, missing hemoglobin, or not abundant enough. So it’s more difficult for the body to deliver the necessary oxygen to the cells that need it.
Depending on the cause of anemia, other types of blood cells may also be affected, such as the B and T lymphocytes, monocytes, or neutrophils that make up the bulk of our immune system.
A red blood cell has a lifespan of about 90 to 120 days before it’s removed from the blood and recycled through the spleen and liver.
This means that any damage to the red blood cells could have an effect for 3 or 4 months before a new cell is produced to replace it.
This is why anemia is a long-term condition, not something that develops or clears up overnight. It often takes about 3 or 4 months of treatment to improve the condition and alleviate symptoms.
What is Hemoglobin?
The functional unit of the red blood cell is a molecule called hemoglobin. This is the part that does all the heavy lifting.
The hemoglobin molecule is basically made of protein (globin) and what is called a “heme group”, a structure that contains iron. This is the place where oxygen and carbon dioxide bind to the blood cell surface.
When hemoglobin isn’t manufactured correctly, we can end up with anemias such as sickle cell, and thalassemia.
We’ll talk more about this later.
What is Anemia?
Anemia is a condition involving insufficient or dysfunctional red blood cell production. It’s the most common blood condition in the United States, affecting roughly 5.6% of the entire population.
There are many different causes for anemia, and CBD oil is useful for some more than it is for others.
It’s important to understand what type of anemia you have.
Symptoms of Anemia
1. Anemia From Loss Of Blood
As seen previously, we need iron to build hemoglobin – the main functional unit of the red blood cell. We normally get that iron through our food, and we will lose some of it through the sweat glands and shedding skin cells. However, this loss is so small it is negligible.
The primary source of iron loss is actually through the loss of blood. Since the primary use of iron is in the form of hemoglobin in our blood, when we lose blood, we lose the iron too.
Typically, when a red blood cell wears out, we recycle the iron to make new hemoglobin. Almost none of it ever gets wasted.
Although a traumatic injury resulting in a lot of blood loss can certainly cause anemia, it’s more common for the condition to develop as a result of low-grade, chronic bleeding. This is because people who have lost a lot of blood usually end up receiving blood transfusions in the hospital, effectively replenishing the blood supply and preventing anemia.
Minor bleeding, however, often goes unnoticed, and accounts for many of the leading causes of anemia worldwide.
Some of the Most Common Examples Include:
- Menstruation, especially if excessive bleeding is present
- Gastrointestinal bleeding, such as ulcers, hemorrhoids, or cancer
- NSAID medication use, a common cause of ulcers
2. Anemia Caused by Dysfunctional Red Blood Cell Production
A) Nutritional Deficiencies
Red blood cells take a lot of resources to manufacture. They’re a very complex cell, with multiple stages of development. They’re also needed in ample supplies on a near-constant basis.
If any of these resources become deficient, or any of the stages of development become impeded, red blood cell production begins to suffer.
The nutrients needed to build red blood cells include:
If any of these nutrients become deficient in the diet, red blood cell production will suffer.
This happens mainly due to iron and B12 deficiencies, which are common in people who eat vegetarian or vegan diets since the majority of foods that contain these nutrients are meats and other animal products.
Pernicious anemia is another related cause for anemia but relies on a condition where the body can’t produce enough intrinsic factor, which is essential for absorbing vitamin B12 from the gastrointestinal tract.
This type of anemia is treated by identifying which nutrients are deficient and adding them to the diet either through food or in supplemental form.
B) Dysfunctional Red Blood Cell Production
Sometimes there are problems in the actual production of red blood cells.
This can be the result of things like:
- Genetically inherited disorders – such as thalassemia
- Cancer therapy –damages the bone marrow tasked with producing red blood cells
- Hereditary spherocytosis – genetic conditions affecting the membrane of red blood cells
- Sickle cell anemia – misshapen hemoglobin molecules, causing distorted red blood cell shape and function
When talking about CBD oil, perhaps the most significant form of anemia is sickle cell anemia.
Sickle Cell Anemia
With this form of hereditary anemia, dysfunctional hemoglobin causes the red blood cells to develop into abnormal crescent (sickle) shapes.
This abnormality causes a set of problems starting with their function:
- Sickle cells don’t work as well as normal cells
- Sickle cells break down faster than normal cells
- Sickle cells get lodged in microcapillaries, causing pain and damage to the area
The condition is usually first seen in childhood.
The signs and symptoms of sickle cell anemia include:
3. Anemia Caused by Premature Destruction of Red Blood Cells
The final category of anemia is caused by premature destruction of the red blood cells themselves.
This, of course, overlaps with some other forms, such as sickle cell anemia, which leads to a premature breakdown of the misshapen blood cells.
Some examples of anemia caused by premature red blood cell destruction include:
- Hemolytic anemia causes excessive breakdown of red blood cells
- Thalassemia, an inherited disorder resulting in misshapen hemoglobin molecules
- Side effects of certain drugs such as Cephalosporins that can cause hemolytic anemia
- Snake or spider venom, especially those containing hemolytic toxins such as cobras
- Liver, kidney, or spleen disease
How to Use CBD Oil For Anemia
So, now that we’ve covered the causes and many different types of anemia let’s get into how CBD oil can benefit anemia patients.
1. CBD Oil and Sickle Cell Anemia
One of the main symptoms of people suffering from sickle-cell anemia is the pain associated with lodgements of the misshapen red blood cells in the microcapillaries. Pain can also occur from poor oxygenation of the tissue resulting from sickle cell anemia.
In some cases, sufferers are prompted to take potent opioid painkillers to manage the pain.
These opioids are a problem over the long-term because they’re highly addictive and bring with them a wide range of negative side effects. So people are now starting to use other methods of pain management for this condition such as marijuana and CBD oil.
A questionnaire-based study done on people living with sickle cell disease involved a few questions on marijuana use and the results found that 36% of the 88 patients in the study had used marijuana to treat symptoms of the disorder.
52% of these people used it to reduce the pain associated with the condition, while 77% suggested they used it for sedation or relaxation purposes.
Another study used an animal model to look at how cannabinoids can be effective at treating the pain from sickle cell anemia. It found that the primary mechanism was through their ability to stabilize mast cells, which are one of the main drivers of inflammation and pain in the body.
In this same study, cannabinoids were also shown to reduce neuropathic (nerve-related) inflammation involved with sickle cell disease.
2. CBD Oil and Iron Deficiency Anemia
CBD itself has little effect on iron-deficient anemia; however, the hemp seed oil often used as the carrier oil in these products is naturally high in iron.
The critical thing to consider here, however, is the dosage.
Typically, the doses used for CBD oil are only a few milliliters per day. But to get the nutritional benefits of hemp seed oil for treating anemia you’d need to consume much more than that.
In 100 mL of hemp seed oil, there’s approximately 8 mg of iron.
According to the National Institute Of Health, the daily requirements for iron in adults between the ages of 19 and 50 is 8 mg/day for men, and 18 mg/day in women.
Daily Iron Requirements:
|7-12 months||11 mg||11 mg|
|1–3 years||7 mg||7 mg|
|4–8 years||10 mg||10 mg|
|9–13 years||8 mg||8 mg|
|14–18 years||11 mg||15 mg|
|19–50 years||8 mg||18 mg|
|51+ years||8 mg||8 mg|
These numbers would mean we require about 100-200 mL of hemp seed oil each day.
These are maintenance doses, however – treating iron deficiency anemia is much more difficult and requires much more iron intake.
Most sources for treating iron-deficient anemia recommend taking 150-200 mg of iron each day, which is the equivalent of about 1.9 L of hemp seed oil per day.
That’s a lot of hemp oil.
According to HempOil.ca, this would cost about $50 per day in hemp oil alone and would require you to drink nearly 2000 mL of the stuff each day.
This is simply not reasonable.
Raw, unshelled hemp seeds are a little better, containing about 9.6 mg of iron per 100 g.
You would need to consume 1.5 kg of raw hemp seeds per day.
Instead, it’s probably best to stick to iron supplements and other high-concentration sources of iron, such as dark leafy vegetables, tofu, and red meat.
Final Thoughts: CBD Oil for Anemia
CBD oil offers only minor improvements to most causes of anemia. Most of these benefits regard symptoms of anxiety and stress, rather than the condition itself.
The main benefit of CBD oil towards anemia comes from its ability to lower the pain and discomfort involved with a particular type of anemia, known as sickle cell anemia.
It could be used to help reduce the nerve pain involved with the condition, which is a particularly difficult type of pain to treat.
It also lowers mast cell activation, which helps reduce pain and inflammation involved with sickle cell anemia.
Other types of anemia have shown little benefit from CBD oil; however, it may be useful for secondary symptoms of the condition including mood disorders, anxiety, fatigue, and frequent infection.
The in vitro effect of delta-9-tetrahydrocannabinol and cannabidiol on whole blood viscosity, elasticity and membrane integrity
The main biological activities of cannabis are due to the presence of several compounds known as cannabinoids. Delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) are two of the main cannabinoids. Studies have shown that the effects of THC can be modulated by CBD.
This study aims to look at the effect of different concentrations of THC and CBD separately and in combination, on blood viscosity, elasticity and membrane integrity.
Blood samples were collected from twenty-four healthy adult non-smokers. Blood viscosity and elasticity were determined using the Vilastic Scientific Bioprofiler for different concentrations (0, 2.5, 25, 50 and 100 ng/ml) of CBD and THC respectively, as well as in extracts with combinations of CBD and THC in 4:1 and 1:1 ratios respectively. Repeated measures analysis of variance (ANOVA) was used to determine the difference between the means of the groups.
Blood viscosity increased significantly with increasing concentrations of both THC and CBD from 25 ng/ml up to 100 ng/ml ranging from 6.45 ± 0.36 mPa·s to 11.60 ± 1.12 mPa·s for THC and ranging from 5.46 ± 0.24 mPa·s to 9.91 ± 1.10 mPa·s for CBD respectively, being more pronounced in the extracts at 21.33 ± 2.17 mPa·s for the 4THC:1CBD extract and 21.76 ± 1.88 mPa·s for the 1THC:1CBD extract. There was no significant increase in elasticity for THC and CBD separately. However, a significant increase in elasticity was observed in the extracts. THC and CBD affected red cell morphology resulting in complete disintegration at the highest concentrations.
THC and CBD increased red blood cell viscosity and elasticity separately and in combination. They also adversely affected membrane integrity.
Cannabis sativa L. is widely distributed and grown throughout most of the temperate and tropical regions of the world. Cannabis is one of the chemically most complex plants due to the presence of a large number of compounds which can exert individual effects and may also interact with each other. Among these compounds, there are approximately one hundred and twenty C21 or C22 terpenophenolic compounds known as cannabinoids (Morales et al. 2017) which are considered to be the main biologically active constituents of the cannabis plant (Hazekamp et al. 2010; ElSohly and Slade 2005).
The cannabinoids belong to ten main subclasses of which five are the most abundant namely, Δ 9 -tetrahydrocannabinol (THC), cannabidiol (CBD), cannabigerol (CBG), cannabichromene (CBC) and cannabinol (CBN). THC has been found to be primarily responsible for the psychoactive properties of the cannabis plant (Hazekamp et al. 2010; Adams and Martin 1996). Lately, increasing attention has been focused on cannabidiol. Studies have shown that depending on the ratio in which they are administered, CBD may have either an antagonistic or potentiative effect on THC (Varvel et al. 2006).
Blood behaves as a viscoelastic material and exhibits both viscosity and elasticity properties (Thurston 1996). Viscosity refers to the energy dissipated during flow primarily due to sliding and deformation of red blood cells and red blood cell aggregates, while elasticity refers to the energy stored in the microstructure of blood during flow due to orientation and deformation of red blood cells (Thurston 1996). Increased blood viscosity has been linked to several disease conditions including sickle cell anaemia, cardiovascular disease, peripheral vascular disease, atherosclerosis, diabetes, stroke and other conditions (Baskurt et al. 2007). Both viscosity and elasticity are directly affected by red blood cell deformability which is itself affected by the mechanical properties (integrity) of the red blood cell membrane (Baskurt et al. 2007).
Cannabis is one of the most widely used illicit drugs worldwide (Goyal et al. 2017). There has also been increased legalization of cannabis for medicinal and recreational purposes (Alshaarawy and Elbaz 2016). There is a paucity of studies showing a direct link between cannabinoids and blood viscosity, elasticity and RBC morphology. While several studies have shown the effect of cannabis on the cardiovascular system (Latif and Garg 2020), they do not directly correlate the effects to blood viscosity, elasticity and RBC morphology in spite of the viscoelastic nature of blood and the dire consequences which can result from red blood cell dysfunction (Başkurt 2003). This study therefore provides further insight about the consequences of cannabis consumption.
There are several diseases in which abnormalities of blood viscosity, elasticity and RBC morphology may play a role. They include but are not limited to sickle cell anaemia, myocardial infarction, myocardial ischemia, peripheral artery disease, cerebral ischemia, diabetes and hereditary spherocytosis (Stoltz 1985). For the majority of these conditions, however, while the effect of blood viscosity and cannabis usage are known separately, there is no indication of how cannabis affects blood viscosity, and therefore, there is no indication about whether the effect of cannabis on these diseases are mediated through its effect on blood viscosity, while the same is true for sickle cell anaemia studies which have shown that vaso-occlusive crises occur more frequently in patients with high blood viscosity, and at least one study has shown that cannabis usage by persons with sickle cell anaemia resulted in more frequent hospitalizations due to the occurrence of vaso-occlusive crises (Ballas 2017), thereby providing an indirect link between blood viscosity, cannabis usage and sickle cell anaemia.
The aim of the study was therefore to look at the impact of THC and CBD on blood viscosity, elasticity and red blood cell membrane integrity which are all interdependent. Taking into consideration the fact that cannabis utilization is itself linked to several adverse outcomes to include arteriopathy, myocardial infarction and strokes and given its increasing utilization globally, it is of utmost importance to add to the body of knowledge surrounding the potential harmful effects of cannabis usage.
Additionally, since a search of the literature did not reveal any study that has directly linked the potential adverse effects of cannabis to its effect on blood viscosity, elasticity and membrane integrity and taking into consideration the increasing interest that currently surrounds the usage of cannabis and the development of medicinal products, it is of utmost importance to determine the effect of the constituents of cannabis on the parameters mentioned and therefore what impact they may have on the health of individuals who utilize cannabis. This study therefore aims to look at the effect of both THC and CBD separately and in combination on whole blood viscosity, elasticity and red blood cell membrane integrity.
Materials and methods
Twenty-four non-smokers consisting of 14 females and ten males ranging in age from 21 to 42 years of age were recruited from the University of the West Indies, Mona Campus. They were recruited by speaking to staff and students of the Department of Basic Medical Sciences, Faculty of Medical Sciences, University of the West Indies, Mona Campus, about the research and soliciting their voluntary participation. No inducements were offered to solicit participation.
Participants had to be 18 years or older, be in good health and have normal haemoglobin (HbAA). Both male and female participants regardless of race were included in the study. All participants signed an informed consent form.
Participants were excluded if they smoked, utilized cannabis by any route of administration, had any circulatory diseases, did a blood transfusion recently and took or were currently using illicit drugs and persons who were currently on medication were not included in the study. The time frame for “currently” was not specified however, and participants were not required to state whether they used alcohol, tobacco or herbal products other than cannabis.
Informed consent was obtained from each participant before recruitment into the study. The study was approved by the UHWI/UWI/FMS Ethics Committee, UWI, Mona.
Eight millilitres of venous blood was collected from the antecubital vein of each participant once and distributed into two vacutainer tubes containing K + EDTA (1.5 mg) as anticoagulant. Samples were kept at room temperature (25 °C) until measurements were done.
THC, CBD and extracts were obtained from Biotech R & D Institute, University of the West Indies, Mona Campus. Stock solutions were prepared using 5% ethanol.
0.1 mg of both THC and CBD were dissolved in 100 ml of ethanol to give stock concentrations of 1000 ng/ml. Aliquots of 2.5, 25, 50 and 100 μl were pipetted from each stock solution into Eppendorf tubes and then made up to 1 ml with blood to give concentrations of 2.5, 25, 50 and 100 ng/ml of THC and CBD respectively. A fifth Eppendorf tube was used as a control to which no THC or CBD was added.
Two extracts containing both THC and CBD in a 4:1 and 1:1 (THC:CBD) ratio were each also made up to 1 ml with blood in 5% ethanol to give a concentration of 50 ng/ml THC. Therefore, the extract with the 4:1 THC to CBD ratio contained 50 ng/ml THC and 12.5 ng/ml CBD while the extract with the 1:1 THC:CBD ratio contained 50 ng/ml THC and 50 ng/ml CBD. These concentrations were chosen based on concentrations of THC in plasma that were observed to give a psychoactive effect in previous studies (Watson et al. 2000).
On addition of the blood, the samples were gently agitated to allow for proper mixing and allowed to incubate for 20 min at room temperature (~ 25 °C) before measurements were taken. Blood samples were agitated by capping the tubes and inverting to mix as well as by rotation on an automated mechanical rocker (Sandrest Systems, Beeching Road, Bexhill, UK).
Analysis of samples
The viscosity and elasticity of the blood samples were measured using the BioProfiler (Vilastic Scientific, Austin, TX, USA). The BioProfiler is capable of giving single measurements of viscosity, elasticity and relaxation time of whole blood at shear rates of 2.51 s –1 , 12.6 s –1 and 62.8 s –1 and strain of 0.2, 1 and 5, respectively. Measurements were done at native haematocrit and at a frequency of 2 Hz, shear rate of 62.8 s –1 and strain of 5 at 37 °C.
The haematocrit was determined by the capillary tube method. The anticoagulated blood was centrifuged, after which a microhaematocrit reader (Vulcan Technologies, Missouri, USA) was used to determine the haematocrit based on the meniscus of the red blood cell layer.
Haemoglobin electrophoresis was performed on blood samples according to the method of Dacie & Lewis, 11th edition (Bain et al. 2012), to ascertain that all participants had normal haemoglobin genotype (HbAA).
The preparation of blood films was done according to the method of Dacie & Lewis, 11th edition (Bain et al. 2012). The slides were then stained with Wright’s stain following which they were visualized using a Nikon Eclipse E200 microscope (Nikon Instruments, Melville, NY, USA) under oil immersion at a magnification of × 100.
The results were analysed using the IBM SPSS Statistics software version 20 and expressed as means ± standard error of the mean (SEM). Repeated measures analysis of variance (ANOVA) which incorporated the Bonferroni test was used to determine the difference between the means. Paired sample T test was also used where necessary to compare the difference in means between THC and CBD at similar concentrations and between the extracts and THC and CBD at 50 ng/ml. The statistical significance was taken at the 95% confidence interval, and a p value of < 0.05 was considered to be significant.
All participants were found to have normal haemoglobin (HbAA) as determined by haemoglobin electrophoresis (Dacie & Lewis, 11th edition).
Viscosity and elasticity
Comparison of the effect of increasing concentrations of delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) (ng/ml) on blood viscosity (mPa·s). Blood was collected from the antecubital vein of 24 participants, and experiments were conducted in vitro. Values are expressed as means for plots (n = 24). Asterisk (*) indicates significant difference from control at p < 0.05. The error bars represent the standard error of each mean (CBD, cannabidiol; THC, delta-9-tetrahydrocannabinol)
Change in blood viscosity (mPa·s) for two extracts containing different ratios of delta-9-tetrahydrocannabinol (THC) to cannabidiol (CBD) (4:1 and 1:1). Blood was collected from the antecubital vein of 24 participants, and experiments were conducted in vitro. Values are expressed as means for plots (n = 24). While the viscosity values for the 4THC:CBD and 1THC:1CBD extracts significantly differ from control, they are not significantly different from each other. Asterisk (*) indicates significant difference from control at p < 0.05. The error bars represent the standard error of each mean (CBD, cannabidiol; THC, delta-9-tetrahydrocannabinol)
When THC and CBD were used separately, there were no significant increases in elasticity (Fig. 3). Similarly, there was no significant difference in elasticity between the two THC:CBD extracts. The results however show a significant increase in elasticity for both extracts (4.41 ± 0.57 mPa .s for the 4THC:1CBD extract and 5.15 ± 0.76 mPa .s for the 1THC:1CBD extract as compared to control at 1.87 ± 0.51 mPa .s in Fig. 4); (F(1.53, 30.50) 7.88, p = 0.004).
Comparison of the effect of increasing concentrations of delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) (ng/ml) on blood elasticity (mPa·s). Blood was collected from the antecubital vein of 24 participants, and experiments were conducted in vitro. Values are expressed as means for plots (n = 24). The error bars represent the standard error of each mean (CBD, cannabidiol; THC, delta-9-tetrahydrocannabinol)
Change in elasticity (mPa·s) for two extracts containing different ratios of delta-9-tetrahydrocannabinol (THC) to cannabidiol (CBD) (4:1 and 1:1). Blood was collected from the antecubital vein of 24 participants, and experiments were conducted in vitro. Values are expressed as means for plots (n = 24). While the elasticity values for the 4THC:CBD and 1THC:1CBD extracts significantly differ from control, they are not significantly different from each other. Asterisk (*) indicates significant difference from control at p < 0.05. The error bars represent the standard error of each mean (CBD, cannabidiol; THC, delta-9-tetrahydrocannabinol)
In the film for the control sample (Fig. 5), the red blood cells appear as normal biconcave discs.
Blood film of control sample. Normal RBC morphology (control sample). Scale = 100 μm
Figure 6a shows the blood film for samples exposed to 50 ng/ml of CBD. The film shows the presence of burr cells. There is also some loss of cytoplasm as well as the presence of blister cells due to separation of haemoglobin from cell membranes. Similar to the cells exposed to 50 ng/ml CBD, analogous changes are seen in the cells exposed to 50 ng/ml of THC (Fig. 6b).
a Blood film of cells exposed to 50 ng/ml cannabidiol (CBD). Blood film showing red cell changes in 50 ng/ml CBD: burr cell formation (echinocytes). Scale = 100 μm (red arrow indicates burr cells; green arrow indicates blister cells, while the yellow arrow indicates extruded cytoplasm). b Blood film of cells exposed to 50 ng/ml delta-9-tetrahydrocannabinol (THC). Blood film showing red cell changes in 50 ng/ml THC: target cell formation, burr cells. Scale = 100 μm (red arrow indicates burr cells; green arrow indicates blister cells, while the yellow arrow indicates extruded cytoplasm)
In addition to burr cells seen in Fig. 6a, Fig. 7a shows some amount of fragmentation and degeneration. These red blood cells were exposed to 100 ng/ml of CBD. The cells exposed to 100 ng/ml of THC (Fig. 7b) also showed similar changes to those observed in the cells exposed to 100 ng/ml of CBD.
a Blood film of cells exposed to 100 ng/ml cannabidiol (CBD). Blood film showing red cell changes in 100 ng/ml CBD: red cell membrane distortion/indentation with occasional red cell fragments. Scale = 100 μm. b Blood film of cells exposed to 100 ng/ml delta-9-tetrahydrocannabinol (THC). Blood film showing red cell changes in 100 ng/ml THC: red cell fragmentation, burr cells. Scale = 100 μm
Figure 8a shows marked red cell agglutination along with some RBC degeneration. These cells were exposed to the extract consisting of a one-to-one ratio of THC to CBD. For the cells exposed to a four to one ratio of THC to CBD (Fig. 8b), there was marked degeneration of red blood cells such that hardly any intact red blood cells were observed.
a Blood film of cells exposed to 1:1, THC:CBD extract. Blood film showing red cell changes in 1:1 THC:CBD extract—marked red cell agglutination with red cell degeneration. Scale = 100 μm. b Blood film of cells exposed to 4:1, THC:CBD extract. Blood film showing red cell changes in 4:1 THC:CBD extract—marked red cell degeneration; hardly any intact RBCs on film. Scale = 100 μm
No results are presented for cells exposed to 2.5 ng/ml and 25 ng/ml of either THC or CBD. This is because these cells were similar in appearance to the control sample. Changes were observed at 50 ng/ml for both THC and CBD and progressively increased with increasing concentrations.
The results indicate that there is a significant effect of increasing concentrations of THC and CBD on blood viscosity. The observed increase is significant at all concentrations except at 2.5 ng/ml. This effect is even more pronounced with the extracts containing both THC and CBD. Two extracts were used with ratios of 4THC:1CBD and 1THC:1CBD. The viscosity values obtained for both extracts were significantly higher than the control sample, but they were not significantly different from each other indicating that regardless of ratio, THC and CBD have a stronger/potentiative effect on each other in relation to whole blood viscosity, when used in combination than when used separately.
The concentrations of THC and CBD used in the study were chosen based on concentrations of THC in plasma that were observed to give a psychoactive effect in previous studies (Watson et al. 2000) where it was shown that on administration of approximately 0.32 mg/kg (range: 0.22 to 0.50 mg/kg) of THC, the resulting plasma concentration ranged from 50 to 100 ng/ml with subjects indicating that they were approximately 50% high when the plasma concentration was 50 ng/ml. As these dosages were based on concentrations observed in the blood following the smoking of cannabis cigarettes with varying percentages of THC, taking into consideration that some THC may have been left in the butt or lost in the side stream smoke, they represent actual dosages that may be consumed by persons ingesting cannabis. The range of concentrations from 0 to100 ng/ml was therefore chosen to reflect the effect of THC and CBD both at low and high concentrations.
The fact that THC and CBD when used in combination have a stronger effect than when they are used individually is another example of the entourage effect which has also been observed in previous studies (Russo 2019). Studies have shown that depending on the ratio in which they are administered, CBD may have either an antagonistic or potentiative effect on THC (Varvel et al. 2006). In this study, however, there were no significant differences in the values obtained for the two extracts indicating that the difference in ratios used did not seem to play a role. The combined effect of THC and CBD was however found to be stronger than the individual effect.
The findings of the present study which indicates that blood viscosity increased with increasing cannabinoid concentrations are also indicative of a concomitant decreased deformability of the red blood cells as the concentrations of THC and CBD increased. This is supported by the results obtained for elasticity which though not significant when THC and CBD are used separately indicate that elasticity is highest when the highest concentration of either cannabinoid is used. The extracts, however, which contain different ratios of both cannabinoids show a significantly increased elasticity in comparison to the control used. Greater membrane elasticity indicates greater storage of elastic energy which therefore means that the red blood cell is more rigid and therefore less deformable as greater energy will be required in order for deformation to take place (Baskurt et al. 2007).
The cannabinoids are believed to exert their physiological effects primarily through two cannabinoid receptors which are referred to as CB1 and CB2 receptors. CB1 receptors are mainly expressed in the CNS, but they are also abundantly expressed in the PNS and other peripheral tissues and organs to include cardiac muscle, hepatic tissue, the gastrointestinal tract and vascular endothelium. The CB2 receptors on the other hand are primarily expressed in cells and tissues of the immune system although they are expressed to a lesser extent in the brain and other peripheral tissues (Subramaniam et al. 2019; Zou and Kumar 2018). Therefore, while cannabis has an effect on numerous systems throughout the body, increasing attention has been focussed on the adverse effects of cannabis on the cardiovascular system which include myocardial infarction, sudden death, peripheral arteritis and stroke (Wolff et al. 2015).
According to the literature, cannabis induces increased production of reactive oxygen species (ROS). This leads to increased oxidative stress which has been implicated in the occurrence of ischemic stroke and possibly other adverse cardiovascular events. It is believed that the production of the reactive oxygen species is primarily mediated by CB1 receptors (Han et al. 2009). The presence of reactive oxygen species can have deleterious effects on the proper functioning of erythrocytes whose main function in the circulatory system is the transport of oxygen and carbon dioxide to and from the lungs and tissues and also to maintain acid base equilibria. In this way, they play a very important role in cardiovascular homeostasis (Red blood cell function and dysfunction 2017). Increased production of ROS can have a profound impact on the integrity of the red blood cell membrane with the possibility of haemoglobin degradation, decreased red cell deformability and haemolysis, all of which have been implicated in serious pathological effects on the cardiovascular system.
One recent study (Ballas 2017) indicated that there was increased vaso-occlusive crises (VOC) in sickle cell patients who utilized cannabis resulting in more frequent hospitalizations. Based on the results obtained in this study, the observed increased incidence of VOC from that study was likely due to consumption of cannabis which could have led to increased viscosity, elasticity and impaired membrane integrity and therefore decreased erythrocyte deformability. Impaired erythrocyte deformability directly affects the ability of red blood cells to pass through small arterioles or capillaries (Baskurt and Meiselman 2003). The decreased deformability could further lead to blockage in the blood vessels, thereby resulting in increased VOCs. This can ultimately prevent oxygen delivery to the tissues and may result in hypoxia.
The increased viscosity and elasticity observed in this study indicate that as concentrations of THC and CBD in the blood increases, more energy is required for deformation and disaggregation of red blood cells. The red cells are therefore less likely to respond quickly to changes in circulation including the ability to change shape under stress imposed by high rates of flow through in the microcirculation. This will directly affect their ability to deliver oxygen to the tissues (Baskurt et al. 2007).
Since red cell deformability is influenced by three distinct cellular components namely cell shape geometry, viscosity of the cell cytoplasm and stability of the membrane (Baskurt et al. 2007; Lester et al. 2014), it would appear that THC and CBD are able to interact with these factors, thereby impairing red blood cell deformability and resulting in the increased viscosity and elasticity observed with increasing concentrations of both substances.
In conjunction with the increased viscosity and elasticity observed, there were increased morphological changes in the membrane of red blood cells with increasing concentrations of THC and CBD both separately and in combination. The results obtained therefore indicate that there is a dose dependent effect of THC and CBD on red blood cells. The cells were normal in appearance when 2.5 ng/ml and 25 ng/ml of THC and CBD were administered separately; however, at 50 ng/ml, there was evidence of impaired membrane integrity which worsened at 100 ng/ml. In the extract containing both THC and CBD in a 1:1 ratio, there was marked red cell agglutination along with degeneration, while in the extract containing THC and CBD in a 4:1 ratio, there was complete disintegration of red blood cells.
Red blood cells (RBCs) play a significant role in blood rheology due to the fact that they are the major cellular components of blood. As such, they are also the predominant factor that affects blood viscosity due to inherent characteristics of the red blood cells to include their ability to orient themselves with flow, haematocrit, the ability to elastically deform in response to mechanical forces and the capability to form rouleaux when there is low flow. Of note here is the fact that red blood cells are able to significantly increase blood viscosity when they lose their deformability which can significantly affect blood flow (Red blood cell function and dysfunction 2017).
While a search of the literature did not reveal specific studies linking RBC disintegration or haemolysis in human cannabis users with cannabis usage, studies have indicated that the psychological effects of THC were highest at the highest concentrations used in the study (Watson et al. 2000).
Changes in red cell morphology will affect the deformability of the red blood cells which in turn will affect their ability to enter microcirculation (Baskurt et al. 2007). The changes observed in red cell morphology therefore concur with the increased viscosity and elasticity observed with increasing concentration.
As previously mentioned, since there is a paucity of information in regard to the effect of cannabis on blood viscosity, elasticity and RBC morphology, this study helps to fill the gaps in knowledge that are not specifically covered in other studies. The results also give an indication that the lower concentrations of cannabinoids, more specifically THC and CBD may be safer and therefore more beneficial. Considering the increased utilization of cannabis for medicinal and recreational purposes, considering the increasing reports of adverse cardiovascular effects associated with cannabis use and considering the importance of blood viscosity, elasticity and RBC integrity in the maintenance of cardiovascular health, this study provides beneficial information which can help inform usage of cannabis.
The study was limited in that it was conducted in vitro rather than in vivo and therefore there is the possibility of variations arising in living systems. Limited quantities of reagents were also a limiting factor which prevented the conduction of the study on a wider scope such as the inclusion of a group of smokers for comparison purposes.
Caution must be exercised in the consumption of cannabis products particularly in persons with sickle cell disease, as this could lead to decreased membrane deformability and increased haemolysis culminating in increased incidence of VOCs, painful crises and even stroke as well as worsening anaemia.