What is CBD Oil?
CBD, or cannabidiol, is one of several compounds found in the cannabis plant. These compounds, known as cannabinoids, are what trigger the various effects of the plant. CBD oil most often comes from hemp plants than marijuana plants (both of which belong to the cannabis species).
CBD is second only to THC in terms of abundance. THC is the cannabinoid best known for creating the characteristic high associated with cannabis. Unlike THC, CBD does not present the same psychoactive effects, and CBD oils are required to have little to no THC (about 0.3 percent THC or less).
Most CBD oils are free of other cannabinoids, though growing research suggests that CBD, terpenes, and other cannabinoids may work in conjunction to complement each other and boost individual effects, known as the entourage effect.1
Even though CBD oil is usually free of other cannabinoids that can have less-desirable effects, there are benefits and side effects of CBD oil that you should be aware of.
The Benefits and Side Effects of CBD Oil
To understand the benefits of CBD oil, you first have to understand the endocannabinoid system. This system comprises molecules known as endocannabinoids and receptors that react to endocannabinoids and cannabinoids, resulting in physiological changes. The two major endocannabinoid receptors are CB1 and CB2. Both of these receptor types are found throughout the body, but CB1 receptors are more abundant in the brain, while CB2 receptors are more abundant outside the brain.2
We performed a literature search for “cannabidiol,” along with the effects we were interested in such as “cannabidiol memory.” Here’s what we found:
It is commonly said that cannabis impairs memory formation. Is there some truth to this widely held belief?
A study involving engineered rodents without CB1 receptor expression (CB1 knockout mice that do not have CB1 receptors) were found to have better memory. This suggests that mice without the CB1 receptor may have an enhanced capacity to strengthen synaptic connections in areas of the brain involved in memory formation.3 Activating this receptor impairs memory formation.
CBD oil is a CB1 receptor antagonist16 which helps it oppose the CB1 activating effects of THC. In another study, 134 cannabis users were tested seven days apart on measures involving memory and psychomimetic symptoms. They were tested once while sober and once while intoxicated by smoked cannabis. Researchers collected samples of cannabis and saliva from each user and analyzed for cannabinoid levels, creating two groups based on the highest and lowest level of cannabinoids found. While groups did not differ in the levels of THC they smoked, those who smoked cannabis high in CBD showed no impairments to memories, while those who smoked low CBD cannabis showed significant impairment of memory recall.4
This suggests that while THC has negative effects on memory, CBD oil has the opposite and may be even able to improve memory.
Seizures are known to be caused by neurons firing and releasing neurotransmitters uncontrollably. Studies have found that CBD may help to manage seizures through its natural inhibitory effect on neurotransmitter release.5 Prescription CBD has been approved by the FDA for certain kinds of seizures in children.
Appetite and Weight Loss
Cannabinoids are known to affect appetite in varying ways. Prescription dronabinol is a cannabinoid derivative that increases appetite.6 Cannabis users often report getting “the munchies” after using cannabis.
A study on different cannabis strains found that cannabis strains high in CBD elicited less of an appetite increase than strains containing higher levels of THC.7 This suggests that CBD may decrease appetite or THC increases appetite.
One concerning study in rats found that the administration of CBD caused statistically significant decreased body weight gain at an age when rats grow and gain weight rapidly. This effect was blocked when CBD was administered with a CB2 receptor antagonist.
However, administration of the antagonist alone did not affect weight gain meaning that CBD’s weight gain decreasing effects involve the activation of the CB2 receptor in addition to other unknown mechanisms.17 This could be concerning as it also implies that CBD may have growth-stunting effects.
Indeed, additional studies are required on the effects of CBD on weight loss and growth in humans.
Users of prescription CBD report increased nausea as a potential side effect.8 However, some studies also suggest that CBD may suppress or lower nausea and vomiting.9 One study found that cannabigerol (CBG) which is the other major cannabinoid blocked the anti-nausea effects of CBD in rats and shrews.20 This suggests that cannabinoids have antagonistic actions in for nausea and vomiting and that additional studies are required.
In a double-blind randomized study, researchers gave 24 subjects with generalized social anxiety disorder either 600 mg of CBD or a placebo. These treatments were administered an hour and a half before a simulated public speaking test. Another 12 subjects performed this test without any medication. The researchers measured visual analogue mood scale, negative self-statement scale, and various physiological measures at six points throughout each subject’s test.
Results found that the placebo group showed higher anxiety, discomfort, cognitive impairment, and alert levels compared to the control. The CBD group showed significantly reduced anxiety, discomfort, and cognitive impairment in their speech performance, along with reduced alertness in anticipatory speech.10
Studies suggest that these potential anxiolytic effects may come from CBD’s activation of glutamatergic cannabinoid receptors, which may work to inhibit excessive arousal.11
Cannabis is suggested for its potential to reduce pain, and research suggests that CBD specifically demonstrates analgesic effects.
In a multicenter, double-blind randomized, placebo-controlled study, researchers provided 177 patients experiencing cancer pain with either a placebo, THC extract, or a THC and CBD extract. Twice as many patients who took the THC-CBD extract showed a reduction of over 30 percent from their baseline pain scores compared to the placebo group. The THC group was actually similar to the placebo group. This suggests that an extract of THC and CBD may help to relieve cancer pain that is not fully relieved by strong opioids.12
Arthritis and Anti-Inflammatory Effects
In a mouse study, mice with collagen-induced arthritis (an autoimmune form of the disease) were given CBD through food and injections. Results showed that both forms of administration were effective in inhibiting the progression of arthritis. These results were dose-dependent with the most optimal effects at 25 mg/kg per day orally and 5 mg/kg per day intravenously. This suggests that CBD’s combination of anti-inflammatory and immunosuppressive properties may have a significant anti-arthritic effect on collagen-induced arthritis.13
There are many causes of hair loss with the most common being pattern hair loss. Pattern hair loss is usually caused by an excess of a hormone called dihydrotestosterone (DHT). In men it presents as balding at the very top and front of the scalp whereas in women it starts at the part in the hair (where the hair splits and goes on either side of the head) and widens.
CBD has been found to decrease testosterone in fetal, immature, and adult mice.19 In the body testosterone is converted to DHT. Lowering testosterone levels could lower DHT levels and help with hair loss. Men who are concerned with testosterone levels may not want to use CBD to this can opt for other natural DHT blockers that work without lowering testosterone instead.
Another mechanism CBD could decrease hair loss is by lowering stress which we went over previously. Stress is a common cause of hair loss. The stress reaction causes the body to release cortisol which and inhibits hair protein synthesis and hair growth, hence the saying “losing your hair” over something.
Insomnia and Sleep
Users of prescription CBD have reported difficulty sleeping and insomnia.8 CBD’s stimulating effects were collaborated in a study comparing the effects of THC and CBD on sleep habits in healthy volunteers. 15mg of THC had sedative effects while 15mg of CBD had stimulating properties as it increased awake activity during sleep and counteracted the sedative activity of 15mg THC.18 From the clinical evidence it looks like CBD use will cause problems sleeping.
CBD presents a variety of potential benefits as well as some negative and unknown effects. One major concern is the recent emergence and discovery of cannabinoid hyperemesis syndrome (CHS). This is characterized by uncontrollable nausea and vomiting after long-term use of cannabis with symptoms only improving after hot showers. The three main cannabinoids in cannabis are THC, CBD, and cannabigerol (CBG) which all have opposing effects on nausea and vomiting.14 Physicians have reported that the use of topical capsaicin cream applied over the abdomen and body have been helpful in the treatment of CHS.15
More research is necessary to fully determine CBD’s benefits and side effects.