The Effects Of Cannabis & CBD On Human Health

Now that it is legal in Canada, there is no use tiptoeing around the subject of marijuana and health.

As a dietitian, my professional activities are centred around empowering people to make decisions within their own contexts to achieve the best possible health, whatever that may mean to them.

Before legalization in 2012, more than 1 in 10 Canadians reported using marijuana and time will tell how legalization affects this statistic and how it is captured.

This number is similar in medical students, 1 in 3 which claim they have used cannabis.

That is just to say that cannabis use, as it may be sometimes perceived, is far from reserved for “troubled youths”, or whatever the case may be.

A recent survey suggested that half of Canadians asked expressed interest in edible marijuana products.

Suffice to say, the consumption and health effects of marijuana is a very relevant topic.

But when I look to Health Canada’s informational page on marijuana, I noticed they paint a pretty grim picture in terms of the negative aspects of marijuana use.

Is it all grim? Why legalize it then?

That brings us to today’s article, a review of the relevant literature on the health outcomes associated with marijuana/cannabis use.

Chronic Pain

Probably the most compelling body of evidence supporting a helpful effect of cannabis use is in the management of chronic pain.

Cognitive Functioning

Cognitive functioning, especially in adolescents, seems to be a real sticking point in the anti-weed argument.

It has long been suspected that regularly smoking marijuana can negatively impact problem solving, emotional control, decision making and other cognitive functions (Crean et al) as well as memory and even academic performance (Volkow et al).

And yet a recently published 2018 paper out of JAMA Psychology suggests that earlier studies on the level of effect that cannabis actually has on the cognitive functioning of adolescents has been overstated, meaning that it may not be as bad as we thought.

During Pregnancy

Marijuana use during pregnancy is associated with an increased risk of low birth weight and birth complications.

Type 2 Diabetes

Although no association exists between cannabis use and type 2 diabetes risk, a 2013 observational study out of the American Journal Of Medicine found that marijuana use was associated with lower fasting insulin levels.

Lung Health

A recent and comprehensive review out of the Journal of Cancer found little evidence that habitual marijuana smokers ( whether short or long-term) were at an increased risk of lung cancer.

There is, however, some suggestion that long-term marijuana use could damage the lungs in other ways.

This 2011 review out of the Expert Review Of Respiratory Medicine journal had the following to say:

There are consistent findings that smoking cannabis is associated with large airway inflammation, symptoms of bronchitis, increased airway resistance and lung hyperinflation. The evidence that smoking cannabis leads to features of chronic obstructive pulmonary disease, such as airflow obstruction and emphysema is not convincing.

The precise effect of smoked marijuana on lung health and long-term outcomes remains unclear and conclusions differ among the studies I was able to access.

Generally, however, there is little dispute in the literature regarding the fact that cannabis smoke is far less damaging than tobacco smoke.

DP Tashkin said this in a 2013 paper:

The accumulated weight of evidence implies far lower risks for pulmonary complications of even regular heavy use of marijuana compared with the grave pulmonary consequences of tobacco

Blood Pressure & Cardiovascular Health

High blood pressure, which I wrote a book about, is one of the most common reasons why Canadians are prescribed medication.

Although there appears to generally be insufficient evidence to draw conclusions about marijuana use and long-term cardiovascular health outcomes, there is some concern that marijuana use may modestly increase blood pressure in the short-term and even increase risk of death from hypertension in the long-term.

This relationship remains observational, inconclusive and worthy of further exploration.

Testicular Cancer

Men who smoke marijuana for a >10 year duration appear to be at a higher risk of testicular cancer.

Current, chronic and frequent cannabis use, as compared to never using it, increases your risk.

Interestingly and perhaps unexpectedly, however, men who use or have used marijuana were found to have higher sperm counts and concentrations.

Inflammatory Bowel Disease

Cannabis use is common in people suffering from IBD (crohns & colitis).

There is some evidence to suggest that cannabis use in people with crohn’s disease may improve sleep and appetite, although further data will be required before firm conclusions can be made.

This 2016 review out of the Gastroenterology and Hepatology journal summarizes it best:

It has yet to be determined in human populations whether cannabinoids have therapeutic anti-inflammatory effects in IBD or are simply masking its many debilitating symptoms.

Body Weight & Appetite

An interesting and complex relationship exists between body weight, appetite and marijuana use.

Obviously increased appetite is a well recognized acute symptom of marijuana use, and yet marijuana users tend to have lower body weights than non-users.

This relationship is certainly multi-factorial, none the less marijuana may be a useful appetite stimulant in those who struggle with meeting their caloric needs.

Intake & Nutritional Status

Interestingly enough, observational studies show that marijuana users tend to have higher energy intakes despite their lower body weights.

Despite higher consumption of foods such as soda, alcohol and high sodium snacks, the nutritional status of marijuana users was similar to non-users although serum carotenoid levels were lower in marijuana users.

For reference purposes foods such as tomatoes, spinach, broccoi, carrots and kale are examples of excellent sources of dietary caretonoids.

Athletic Performance

There is only minimal and low quality evidence to support the use of marijuana as truly effective when it comes to improving physical performance.

It appears better data will be needed before firm conclusions can be drawn.

Sleep Apnea

The American Academy Of Sleep Medicine (AASM) suggests that there is insufficient evidence to support the use of cannabis in the treatment of sleep apnea.

Concluding Remarks

Today’s article was meant to serve as a neutral and objective exploration of what we currently know about the connection between marijuana use and health outcomes.

As you could probably tell, we still have a lot to learn.

Until next time,

Andy De Santis RD MPH


Bonus Content: CBD And Anxiety

Some of you may have hard of or be familiar with CBD, also known as Cannabidiol, which is essentially a cannabis component that lacks THC ( aka none of the the stuff that gets you “high”).

It is available in a variety of forms, including oils and capsules, and has been increasingly studied for it’s potential health effects, especially as it relates to anxiety.

Although research in this area is in its relative infancy, it does appear that oral doses in the 300-600 mg range is effective at reducing anxiety specifically in Seasonal Affective Disorder (SAD).

More research will be required to determine how far reaching this potential benefit is and how it is modulated between acute and chronic exposure to CBD across a variety of anxiety-related conditions.