Grab a coffee and get comfortable, because after months of research, we’re about to break down the scientific research on marijuana. And if you want to see all of our research, our marijuana page has 639 citations (and counting).
Marijuana is an herb that contains molecules called cannabinoids. The most famous cannabinoid is tetrahydrocannabinol, also known as THC. THC is responsible for the high that inhaling or ingesting marijuana causes.
Traditionally, marijuana has been used to treat a variety of inflammatory and gastrointestinal ailments. It has also been used to reduce anxiety and help alleviate cognitive decline.
Today, marijuana is used an adjuvant treatment for cancer, meaning it is taken alongside other drugs. It is used alongside chemotherapy because marijuana increases appetite, which prevents the weight loss associated with chemotherapy. Maintaining weight during chemotherapy greatly improves patient survival rates during cancer treatment. Marijuana is not a potent anti-cancer agent by itself.
During cancer treatment, marijuana is used primarily to improve appetite and alleviate pain.
Marijuana has been successfully used to treat other conditions characterized by nerve pain. It can also be used to treat glaucoma due to the reduction in eye pressure it causes. Marijuana is also very promising in the context of treating Parkinson’s and Alzheimer’s disease.
Marijuana is a very popular recreational drug due to its ability to reduce anxiety, alter the perception of your surroundings, and increase euphoria.
Marijuana acts on two receptors, located on cell walls. These cannabinoid receptors are actually named after the plant itself. They are known as the first cannabinoid receptor (CB1) and the second cannabinoid receptor (CB2).
CB1 is responsible for the immediate and psychoactive effects of marijuana, while CB2 determines the long-term and anti-inflammatory effects.
Using marijuana can lead to tolerance, which means more marijuana will be needed to achieve the same effect. Tolerance is caused by a process called internalization. When the CB1 receptor is internalized, it means it withdraws into the cell and can no longer come into contact with THC.
Internalization doesn’t just lead to marijuana tolerance. Other receptors associated with the CB1 receptor will follow CB1 into the cell. For example, the N-methyl-D-aspartate (NMDA) receptor is internalized along with CB1. This leads to protective effects against anxiety and epilepsy, but it also causes the temporarily impaired memory retention associated with marijuana.
Most of the benefits marijuana provides are related to its psychoactive effects. It is effective for reducing stress by alleviating anxiety, increasing euphoria, and causing users to slightly disassociate from their environment.
Marijuana can also help people with low body weight increase their food intake. Since it can also reduce nerve pain, marijuana can be very beneficial to people suffering from conditions characterized by chronic pain.
More research is needed to determine if marijuana can provide benefits for people suffering from Parkinson’s, Alzheimer's, and multiple sclerosis, though preliminary evidence is promising.
The biggest drawback associated with marijuana use is the internalization of the NMDA receptor, which can lead to poor memory retention.
Occasional marijuana use will not impair long term memory, or the capacity to form memories.
Activating the CB1 receptor also increases activity and blood flow in a region of the brain called the anterior cingulate cortex (ACC), which leads to an increase in diastolic blood pressure (the second number on the blood pressure readout). This means that marijuana, when combined with stimulants, can increase the risk of a cardiovascular injury, like a heart attack.
Frequent marijuana use will turn this blood flow increase into a decrease, once the CB1 receptor is internalized. Very heavy usage, meaning five or more joints a day over a period of several years, can actually cause the ACC to shrink. This can hurt attention span and may increase the risk of developing psychosis. If the ACC is affected in this way, it may not return to normal even if marijuana usage is stopped.
Using marijuana causes a temporary state of lowered memory retention, meaning it becomes harder to remember things in the short term. It’s the same feeling that you get when you check your watch, only to realize immediately after that you don’t remember the time. This effect does not cause long lasting memory problems.
Frequent marijuana users may experience slight cognitive impairment, or ‘brain fog’, if they stop using marijuana, but this feeling disappears after two weeks, leaving no long term damage.
Very heavy marijuana users may have more trouble focusing and learning new things if the ACC has been affected.
There is evidence to suggest marijuana use can increase the risk of schizophrenia, but there is also evidence that suggests the opposite. Early studies found that people with schizophrenia sometimes believed that marijuana use would alleviate their symptoms. Since marijuana use does increase blood flow to the ACC, and schizophrenia is characterized by reduced ACC activity, it makes sense that occasional marijuana use could temporarily alleviate symptoms of schizophrenia.
This does not mean marijuana causes schizophrenia, and it should not be considered a treatment option for schizophrenia.
Marijuana use reliably increases appetite, though this effect is subject to tolerance. Still, the effect is powerful enough to make marijuana a popular pharmaceutical, since its appetite-increasing effects help cancer patients stay at a healthy weight, which leads to higher survival rates.
Marijuana’s anti-inflammatory effects are caused by CB2 activation, which makes it a potential therapy for treating cognitive diseases characterized by inflammation, like Parkinson’s and Alzheimer’s.
Unfortunately, since activating CB1 can cause issues with memory retention, more research is needed before marijuana can be recommended specifically to alleviate Parkinson’s and Alzheimer’s.
Marijuana is illegal in many parts of the world, and many sports organizations have explicitly banned its use. In fact, scientists have actually tested how much second hand inhalation is required to test positive on a urine test to determine if athletes could legitimately use the excuse that they were around other users, but didn’t personally partake.
It turns out that to test positive for marijuana after second hand inhalation would require exposure to at least 16 joints in a closed room approximately the size of a bathroom for at least an hour. That’s a lot of inhalation.
Marijuana use increases diastolic blood pressure and thus should not be used alongside stimulants, especially by people already at risk for heart attacks and other cardiac conditions. Otherwise, infrequent marijuana does not pose a serious health risk, provided that the influence of marijuana doesn’t lead you to do something stupid.
The risks of marijuana come with heavy and near-daily usage. Marijuana causes impaired memory retention, so when that effect is repeated daily across multiple joints for years, learning can become difficult.
Chronic heavy users of marijuana can experience reduced ACC weight. This is brain atrophy and should be taken seriously. However, it is the only negative effect of marijuana that persists even after marijuana usage is stopped.
Maintaining sensitivity to the psychoactive effects of marijuana requires infrequent use. Some people’s CB1 receptors may start to internalize even while using marijuana only once a week. Using marijuana twice a month will make you more likely to experience marijuana’s beneficial effects in a safe and sustainable way.
If you have not used marijuana before, make sure your first time is with other people you trust in a safe environment. Psychoactive drugs can have unexpected side-effects, so safety is key to a good experience.
When it comes to chronic usage, marijuana’s greatest benefits include a pain reducing effect and an increase in appetite, which is critical during chemotherapy. Conversely, the biggest downside with chronic usage is potential ACC (a component of the brain) shrinkage and the reduced capability for learning and remembering.
During infrequent usage, the risk of reduced learning capability is much lower, whereas the benefits of pain reduction and increased appetite remain, though the effect is not as strong.
Want to read the full science? See our Marijuana page.
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Examine.com editors have finished going over Taraxacum officinale, more commonly known as dandelion. The same yellow plant that pops up in your yard every spring is used around the world in various traditional medicines and as a diuretic. In fact, it’s used so frequently for its urine-inducing property that its French name, pissenlit, actually means ‘wet the bed’.
Traditional medicines that include dandelion usually intend it as a treatment for gastrointestinal ailments or inflammation. Some preliminary rodent evidence does suggest dandelion may be able to increase the rate at which food exits the stomach and enters the small intestine, but much more research is needed to confirm if this effect can be replicated through supplementation.
Though it is frequently used as a diuretic, dandelion lacks research on its effects. It is effective when taken by humans, but the potency of the effect and mechanism through which it occurs requires further investigation. It is possible that the diuretic effect is caused by a high potassium to sodium ratio. Dandelion is very high in potassium, with about 2.45% of its roots, dry weight, being potassium, while sodium makes up only 0.33% of the plant.
Dandelion can be added to salad to increase dietary potassium intake. Just don’t start using the clippings from your lawn. Dandelions growing in urban and suburban environments are frequently exposed to pesticides.
Dandelion is not recommended for supplementation at this time, since it has limited evidence for its effects.
A recent study has revived the supplement market’s interest in a compound called (-)-epicatechin, a molecule found in chocolate. This molecule is claimed to be a myostatin inhibitor. Myostatin deficiencies are well known for their biggest side effect: greatly increased muscle mass without the major side-effects associated with anabolic steroids. Hindering myostatin’s actions would be able to replicate this effect.
Myostatin is a myokine, a kind of regulating molecule released by muscles. The ‘opposite’ of myostatin is a myokine called follistatin. Unlike myostatin, which suppresses muscular growth, follistatin indirectly promotes muscle growth because it hinders myostatin signalling.
While there are a few supplements that are known to interact with myostatin signaling (like sulforaphane), none had been tested in the context of human supplementation, until now.
This recent study examined the effects of (-)-epicatechin when supplemented by people. Already, new supplements are popping up on the shelves, containing (-)-epicatechin and claiming to be myostatin inhibitors.
Myostatin and follistatin both have potential to alter muscle growth rates, but supplements and foods affecting these molecules have limited evidence in humans.
Should you supplement (-)-epicatechin or eat more chocolate to build muscle? Let’s dissect the study and find out.
This was a proof of concept study in three parts. A proof of concept study is designed to test whether a compound will have the effect researchers hypothesized, as well as determine if further studies are appropriate.
The first part of the study was done in vitro, meaning outside the body in a test tube or petri dish. Scientists assessed muscle cells taken from people of different ages. When people age, their muscles tend to have higher myostatin levels and lower follistatin levels. The in vitro part of the study confirmed this relationship.
The second part of the study was the mouse study. After measuring the myostatin and follistatin levels of old and young mice to confirm the age-related difference, researchers gave the rats 1 mg (-)-epicatechin per kg of body weight, twice a day. Over two weeks, young mice experienced a 15% decrease in myostatin with no change to follistatin. Older mice, meanwhile, experienced an 18% reduction in myostatin and a 30% increase in follistatin.
Two weeks is not enough time to notice any changes in muscle tissue mass, so researchers did not measure it.
In the third part of the study, six middle-aged people supplemented 1 mg of (-)-epicatechin per kg of body weight, twice a day. This translated to about 75 mg of (-)-epicatechin, twice a day, for a total daily dose of 150 mg.
The published study reports that the follistatin to myostatin ratio of the six middle-aged subjects increased +49.2% (follistatin)/ -16.6% (myostatin), which suggests an increase in follistatin levels and a decrease in myostatin levels. However, the exact changes in myostatin and follistatin levels were not reported.
Though a minor (7%) increase in hand grip strength was observed, muscle tissue mass was not measured, and there was no placebo group for comparison.
This study fulfilled the goals of a proof of concept study, because it provides evidence to suggest a possible relationship between (-)-epicatechin, follistatin, and myostatin levels, which can be investigated in future studies.
A recent study is the first to show that supplemental (-)-epicatechin increases the follistatin to myostatin ratio in humans.
The biggest difference between this study and the new myostatin supplements are the doses. The study used a 150 mg daily dose, while the supplements range from 250 - 500 mg (-)-epicatechin per dose, for a total daily dose of 500 mg - 1,000 mg.
The 75 mg used in the study can be supplemented through dark chocolate consumption. Eating 50g of pure dark chocolate containing at least 50% cocoa a day will provide a similar amount of (-)-epicatechin as the dose used in the study. The higher the cocoa content in the chocolate, the less you need to eat. For example, if you eat dark chocolate containing 85% cocoa, you’d only need to eat 30 g for an equivalent dose.
Milk and white chocolate have a much lower cocoa content and subsequently, contain little to no (-)-epicatechin.
It’s easy to obtain the studied levels of (-)-epicatechin by consuming a small to moderate amount of dark chocolate daily.
Keep in mind, this study had a very small sample size, just six people, and there was no placebo control. Furthermore, only the ratio of myostatin and follistatin changes were published, not the actual numbers. This study does not provide evidence to recommend (-)-epicatechin as a muscle growth agent, but it does lay the groundwork for future research and suggests (-)-epicatechin is a promising muscle growth supplement.
Since (-)-epicatechin provides other health benefits and is very safe, it is possible to test this potential muscle growth agent for yourself by eating dark chocolate twice a day.
In the future, (-)-epicatechin may be a novel and exciting muscle growth enhancing compound, but there is not enough evidence to recommended it as a dedicated dietary supplement today.
Due to the preliminary nature of studies, there is not currently enough evidence to support (-)-epicatechin for muscle growth. However, dark chocolate is safe and provides other health benefits, so consuming it regularly may not be a bad idea.
To bring you up to speed: kombucha is a fermented drink product, made by fermenting already-fermented green or black tea. This is why kombucha is called ‘doubly-fermented’ tea. However, if kombucha is fermented for too long or in unsanitary conditions, it can develop very dangerous properties.
One of the molecules found in kombucha is called D-saccharic acid 1,4 lactone (D-saccharolactone). D-saccharolactone has been studied for its ability to prevent colon cancer, diabetes and hyperglycemia.
Unfortunately, more research is needed to determine if D-saccharolactone is an effective protective compound when supplemented or consumed through products like kombucha. D-saccharolactone has been shown to be effective when studied in vitro, meaning outside of the body, in a test tube or petri dish, but more studies are needed to determine if these effects extend to oral consumption of kombucha. It is not uncommon for a compound to be very promising in vitro but not do much when consumed (for example, see glutamine).
What sets kombucha apart from other potentially dangerous food products is how little is known about the strains of toxic bacteria and fungi that make improperly brewed kombucha dangerous.
Dangerous food products can fall into several groups:
Spirulina, an algae sometimes used as a supplement, can be dangerous if it is contaminated with microcystin, a kind of toxin. Spirulina producers are aware of this potential danger, and test spirulina for microcystin.
Some herbal supplements can be toxic if they are contaminated with other species of herbs. Herbal producers run tests to make sure their herbal supplements are pure, and subsequently, safe. For example, Stephania tetrandra is one of the four plants that can make up the traditional Chinese medicine Fang Ji. In the past, it has been contaminated with a toxic plant called Aristolochia fangchi, which can also be called Fang Ji. Anyone that produces Stepania supplements knows to test for Aristolochia.
Other food products, when prepared improperly, become toxic or dangerous. Chicken, for example, can be dangerous if it is eaten raw or undercooked. But while you can use a thermometer to determine how safe chicken is to eat, there is no easy test for determining kombucha’s safety. Unlike spirulina, researchers don’t know what fungi and/or bacteria strains are dangerous in kombucha, and which provide the health effects.
Though kombucha may have potential health benefits, it can be dangerous to drink because many of its risks are still unknown. Unsanitary kombucha can cause death, organ failure, and there’s even been one report of cutaneous anthrax.
Any compound that provides unique benefits, but has also been shown to be toxic, can still be supplemented if the toxicity is carefully controlled for. Unfortunately, the specific toxins in kombucha have yet to be identified. More importantly, more research is needed to determine whether kombucha really does provide unique health benefits. With little proven health benefits, and questionable toxicity, Kombucha cannot be recommended for supplementation or consumption at this time. Future evidence must identify the toxic strains in kombucha, or confirm the unique therapeutic effect of saccharolactone (when consumed through kombucha), for kombucha to be recommended as a health drink.
If you do choose to drink kombucha, it is very important to research the producer. Only purchase kombucha from sanitary producers with properly trained staff. Kombucha is not recommended as a therapeutic or preventative drink. Instead, consider options like black or green tea, or fermented food products like kimchi or sauerkraut.
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By far, the #1 question we get is: "What supplements should I take for _?"
In this case, the blank could be anything, but it's usually about a dozen common things. Fat loss. Muscle Gains. Testosterone. Joint Pain.
Occasionally we get the interesting demographic ones, e.g. seniors or vegetarians.
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And while we solved 90% of supplement confusion over a year ago, we have now finally solved the last 10%
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The world of supplementation is far more complex than just "good" and "bad." In reality, it's more like "your base" "things that we know work" "things that may work" and "overhyped that are a waste of your money." And that's how we approached our Stack Guides.
The full list of Stack Guides:
Each Stack Guide takes on a common supplement concern. We then break down supplements into four categories - Base Supplements, Proven Options, Unproven Options, and Caution/Overhyped. We cover each supplement and carefully breakdown how to take it.
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Kombucha is a tea product, known as doubly fermented tea or fungal tea. It’s often claimed to have stronger anti-cancer properties than other teas.
Kombucha comes from the same plant that produces green and black tea, Camellia sinensis. The process of brewing kombucha involves fermenting already-fermented black tea with fungi and bacteria. During fermentation, the tea becomes mildly carbonated, acidic, and acquires its distinct vinegary taste. The fermentation process also produces new bioactive compounds and alcohol. Don’t try getting drunk off of kombucha, since the alcohol content is low and drinking a lot of kombucha can be dangerous.
The most important bioactive compound in kombucha is called D-saccharic acid 1,4-lactone, also known as saccharolactone. Saccharolactone is claimed to exert anti-cancer effects in the colon, and it’s supposed to help with detoxification too.
Unfortunately, the potential potency of saccharolactone, as seen in vitro, is difficult to apply to the human body, for two reasons:
There have not been any human studies done on saccharolactone by itself, or in kombucha.
Improper preparation of kombucha results in toxicity and the risk of death.
While kombucha can be prepared safely, improper sanitation can cause cross-contamination, which leads to the growth of toxic fungi and bacteria. Kombucha is a risky supplement option, since it is difficult to identify toxic strains of fungi. Moreover, further research is needed to identify the bacteria strains responsible for kombucha’s health effects. If kombucha is fermented for longer than a week, it will start to develop these toxic properties.
Kombucha made incorrectly can do a lot of damage to the human body. Case studies examining harm done by kombucha consumption have noted death, organ failure, and even one report of cutaneous anthrax.
Ultimately, there is no proven and significant benefit of drinking kombucha. It’s not a very practical health supplement, considering there’s hardly any evidence for its health effects, but plenty of evidence for the damage it can do. If you do choose to drink kombucha, make sure to purchase it from trustworthy producers with sanitary working conditions and properly trained staff.
NOTE: You can see all sources on our Kombucha page.
Added July 21 2014: An Update on Kombucha: Understanding Risk and Evaluating Toxicity
As Examine.com continues to grow (over 33,000 scientific references now), it's important that we remain versatile and ready for the future. A lot of companies start off successfully but get bogged down as they struggle to scale their operations.
We have no interest in slowing down. There's way too much noise out there already.
As such, we're announcing some changes to help ready ourselves for 2015 and beyond.
Firstly, Dr. Spencer Nadolsky will be stepping down as our director. Dr. Nadolsky found that he missed having one-on-one interactions with people (after all, what's why he became a doctor). With that said, he will remain onboard as our medical editor (his expertise, both in theoretical matters and hands-on, is invaluable). He's not going anywhere!
The good news: stepping up as the new Director of Examine.com is Kamal Patel. With an MBA and an MPH (Master of Public Health) from Johns Hopkins, and on hiatus from his PhD in nutrition at Tufts, Kamal Patel brings the perfect blend of business savvy, big-picture health applications, and understanding the nitty gritty of scientific research (he's been published in peer-review over a dozen times). His larger involvement in our future will only be good news for us (for those that remember us linking to a LifeHacker article on why there's so much confusion over health and nutrition, it was Kamal's broad knowledge that contributed heavily to that article).
Secondly, as we grow, we realize that having a large breadth of expert individuals looking over our research and ensuring we haven't missed any crucial detail only helps everyone. Thus, we are now adding Reviewers to Examine.com. While the Editors will continue to perform the bulk of the primary research, Reviewers will be brought in after our internal discussion has concluded to ensure that nothing is amiss and no theoretical or practical points have been overlooked. The addition of Reviewers lets our team remain versatile and lets us work with knowledge experts without greatly slowing down our research.
As such, we are proud to announce the addition of our first reviewer: Dr. Cassandra Forsythe. Having a PhD in exercise science and nutrition, and also a registered dietitian, she brings a wealth of knowledge to Examine.com. She's already started reviewing our work!
Please be sure to give Kamal and Dr. Cass a very warm welcome on our Facebook page. We're extremely excited to have them onboard.
Today at Examine.com, we bring you a page on Adrafinil, a synthetic stimulant. Adrafinil is a precursor to modafinil, which means adrafinil is metabolized into Modafinil after supplementation. The two compounds have very similar properties.
In fact, a lot of research on adrafinil stopped after it was discovered that modafinil was a more effective option. Adrafinil takes more time to start exerting its effects (since it has to be metabolized first), which meant the faster-acting modafinil is used to treat disorders like narcolepsy. Modafinil also leaves the body faster, which makes it less likely to interfere with regular sleeping patterns.
Both adrafinil and modafinil are being investigated for their roles as nootropic agents, as they have potential for enhancing memory formation. Both supplements are used to reduce sleepiness and improve alertness. Evidence suggests they may even be more effective than caffeine at improving focus.
Though there is no published evidence to suggest adrafinil is bad for the liver, the producers of adrafinil have issued a warning against prolonged usage. Since adrafinil is metabolized in the liver, adrafinil should not be supplemented for more than six months at a time.
Rose Hip has been added to the Examine.com database. Rose hip is a term used to refer to the fruit of rose plants, though it usually refers specifically to the fruits of Rosa canina, or ‘dog rose’.
Rose hip is usually supplemented in a powdered form. Keep in mind, it’s a fruit, so the powder will have calories. Taking rose hip daily can alleviate symptoms of osteoarthritis and rheumatoid arthritis. Taking rose hip consistently over several months will reduce joint inflammation and pain while improving mobility because it reduces the accumulation of immune cells in inflamed tissues.
Rose hip is hypothesized to be able to help with diabetes and obesity as well, but further research and evidence is needed before rose hip can be specifically recommended for anything but arthritis.
Rose hip supplementation uses a high dose, between 5-40g of the dehydrated powder. It’s a fruit, after all. Supplementing rose hip in low doses (like those that can fit in a single capsule) is not effective. Rose hip’s effects are very mild. While supplementation does offer benefits for joint problems, other supplements may be more effective.