Bone may be hard like a rock, but it is very much alive beneath the surface. Bone is actually living tissue. In osteoporosis, the creation of new bone cannot keep up with the removal of old bone. Recently, CBD has proven beneficial for a wide array of diseases. Could CBD for osteoporosis be a new alternative?
What is osteoporosis?
Osteoporosis is an accelerated weakening of bone tissue with age, associated with several factors including poor nutrition, menopause, certain cancers, and genetic changes. It is most common in aging women, but it is found across all people. To understand osteoporosis, first you need to understand bones.
What are bones?
Bones protect our internal organs like our heart, and lungs. They support our body’s structure so we can move and function. Exercise and a balanced diet help bones become dense and strong through the orchestrated accumulation of certain minerals (i.e. Calcium and Phosphorous).
Our bones have a strong outer layer called “compact bone”, and beneath that is a soft layer which resembles a sponge, lending the name “spongy bone”. Within this “matrix” of hard and soft bone, other cells known as osteoclasts and osteoblasts break-down old bone and regenerate new bone, respectively.
In a process known as bone remodeling, new bone is always being formed, while old bone is being removed and recycled. In healthy bone, this happens at the same rate. The sex hormones, testosterone (male) and estrogen (female), play an important role in maintaining the balance of bone remodeling.
As humans age, the process of bone remodeling is affected negatively impacted. Aging individuals produce lower and lower amounts of their respective sex hormone, leading to decreased production of new bone while contributing to accelerated break down of old bone.
This is osteoporosis in a nutshell.
Cause(s) of osteoporosis
Osteoporosis occurs when the creation of bone (by osteoblasts) is outpaced by the breakdown of bone (by osteoclasts). Osteoclasts break down bone faster than osteoblasts are able to produce new bone. The activity of both types of osteocytes is directly controlled by the levels of sex hormone present in the blood. Testosterone and estrogen stimulate the activity of osteoclasts and osteoblasts.
As the levels of sex hormones drop with age, the activity of osteoblasts decreases much more than the activity of osteoclasts, resulting in an imbalance between bone which is degraded by osteoclasts and bone which is created by osteoblasts.
This imbalance is manifested by decreased bone density and increased likelihood of stress or compression fractures, specifically in the hips, spine, and hands.
While testosterone and estrogen levels inevitably decrease with age, certain factors can increase chances of osteoporosis. They include low calcium intake, sedentary lifestyle, genetic factors, the presence of cancers or other diseases, and the treatments of these diseases which may further impact levels of sex hormones.
Diagnosis and characteristics of osteoporosis
According to the Center for Disease Control, 24.5% percent of women, 65 or older, have osteoporosis in their neck or spine.
A physician will be able to determine a diagnosis by ordering a test that scans over the body and uses low levels of X-Rays to determine the quantity of minerals within the bone the percentages of these minerals with the bone such as calcium, and phosphate.
Current treatment options and best practices for osteoporosis
The best practices for patients with osteoporosis is based on the severity of their situation. If they are low risk for bone fracture then they may not have to take medication and can instead focus on lifestyle changes which can reduce bone loss.
If the patient has a high-risk for bone fracture then they may have to take medication and explore other options. After the age of 30 an individual can reduce the possibility of osteoporosis by exercising often and maintaining a healthy diet high in calcium.
The most common methods of treatment are as follows.
- Medication: High risk patients may have to take drugs such as Boniva, Fosamax, Atelvia, or Reclast, which include the following side-effects: nausea, abdominal pain, heartburn like symptoms, and sometimes an increased risk of femur fracture.
- Hormone Therapy: for women who are higher risk, especially after menopause, estrogen therapy can help to promote formation of more bone. The major problem is that estrogen therapy also increases risk for breast cancer, heart disease, and blood clots. In light of this, younger women are better candidates for hormone therapy to mitigate risk before it is too great.
- Lifestyle Choices: Smoking increases the chance that bones may fracture. Patients should also avoid drinking more than two glasses of alcohol per day, as excessive alcohol consumption decreases osteoblast activity. Carbonated beverages also contain high levels of carbonic acid which degrades bone tissue and promotes osteoclast activity; generally lowered systemic pH is correlated with increased osteoclast activity.
Is endocannabinoid deficiency involved in osteoporosis?
The endocannabinoid system is heavily involved in the regulation of osteoblast and osteoclast activity. The endocannabinoid system (ECS) is a major regulatory network in many different organ systems and tissue types. Because it regulates so many different processes, its dysfunction is highly implicated in a number of disorders, including osteoporosis.
The ECS is comprised of cannabinoid receptors which are activated by endocannabinoids – a type of signalling molecule. The endocannabinoids themselves are produced and degraded by enzymes. The presence of cannabinoid receptors, endocannabinoids, and their enzymes in a given tissue signifies that the ECS plays a role in regulating the activity of that system.
Specifically, cannabinoid receptors decrease the activity of the cell when they get activated by a cannabinoid. This means the role of cannabinoid receptors (CB1, CB2, and GPR55) in osteoclasts is to reduce the activity of the osteoclast – namely, to reduce bone resorption. Consequently, decreased expression of ECS receptors is correlated with osteoporosis.
A paper published to the US National Library of Medicine explored the possibility of bone healing effects in CBD. Adult mice modified to lack cannabinoid receptors experienced faster bone loss than was reported than in normal mice.
Does CBD improve cases of osteoporosis?
A study conducted in Israel concluded that CB2 receptor expression promoted bone formation. There is an incredibly complex relationship between osteoporosis and the endocannabinoid system. The study found, in concordance with existing literature, that reduced CB2 receptor expression was correlated with osteoporosis, and that signaling mediated by CB2 in osteoclasts is one of the primary regulatory pathways of bone remodelling.
There is no simple explanation of the exact differential roles of CB1, CB2, and GPR55 in bones. This is because cannabinoid receptors have the same negative effect on the activity of both osteoclasts and osteoblasts, meaning that they regulate both aspects of bone remodeling, just to different degrees in different cells. Furthermore, they are rarely both expressed in the same cells.
Therefore, it is suggested that modulation of the ECS could be beneficial for rebalancing the process of bone resorption as opposed to increasing the activity of only osteoblasts or decreasing the activity of only osteoclasts; selective targets of only one kind of cannabinoid receptor may ultimately prove the most effective cannabimimetic treatment option for osteoporosis.
CBD itself has two distinct effects in the endocannabinoid system.
First, it negatively modulates CB1 and CB2 receptors, reducing their ability to bind to agonists, the compounds which activate them (AEA, 2-AG, THC, etc.). This is one example of the entourage effect in action, as CBD reduces the effect of other compounds which act on the same cannabinoid receptors.
Second, it inhibits several enzymes, including FAAH (fatty acid amide hydrolase, responsible for breaking down THC, and most endocannabinoids as well). By inhibiting the enzyme which breaks down the endocannabinoids, CBD increases the effect that they are able to exert on the cannabinoid receptors.
This is somewhat paradoxical, as CBD both decreases and increases the effect of the same molecules bound to the same receptors. This complex interaction is not yet well understood, but it suggests a somewhat “buffer-like” effect of CBD on endocannabinoid system activity.
While the exact mechanisms are not well understood, the conclusion remains the same: CBD is helpful and effective at reducing the likelihood of osteoporosis and improving the health of the endocannabinoid system within bones.