Arabinogalactan is a natural immune booster found inside the leaves, roots, and sap of many plants. First discovered in larch in the 19th century, recent research reveals it may help prevent colds, combat infections, and relieve allergies. Read on to learn when it’s beneficial and when you may want to avoid supplementing.
What is Arabinogalactan?
Arabinogalactan is a natural compound found in many plants and a key ingredient in plant gums, such as gum arabic .
Certain species of bacteria have arabinogalactan in their cell walls for structural support .
A major commercial source of arabinogalactan is the North American larch tree. Extracts from this tree are referred to as larch arabinogalactan .
Arabinogalactan has several unique properties, including high solubility and stability. This makes it useful as a thickening and stabilizing agent .
Here’s the best part.
Where can we find arabinogalactan?
Varying concentrations are contained in the seeds, leaves, roots, fruit, and sap of many plants. It may come as a surprise, but arabinogalactans have been a part of the human diet for thousands of years .
Some good dietary sources include :
- Leek seeds
Commercially, it is extracted from the North American larch tree, and with good reason. This specific larch species contains a very high concentration (up to 35%) of arabinogalactan .
What Does it Contain?
Arabinogalactan is a polysaccharide, meaning it is made up of many smaller sugar molecules. Specifically, arabinogalactan contains long chains of the sugars arabinose and galactose, which is how it got its name [5+].
The composition of these sugars can vary depending on the species of plant. For example, larch arabinogalactan contains galactose and arabinose in a 6:1 ratio [5+].
Arabinogalactan is also commonly found in combination with proteins. Research is finding that arabinogalactan-proteins have their own unique functions in plants .
Why does this all matter?
Individuals wishing to take supplements should know that the arabinogalactan source is important. Different sources can have different concentrations of sugars and other compounds.
On top of that, researchers use different plant sources for their studies. One source of arabinogalactan may not produce the same health effects as another source.
Snapshot of Arabinogalactan
- Naturally found in many plants
- Boosts the immune system
- Has cancer-fighting potential
- Protects the stomach
- May help with allergies
- May help with dry eyes
- May relieve pain
- May help in diabetes
- Not well studied in humans
- Best avoided by people with autoimmune issues
- May cause bloating and flatulence
Health Benefits of Arabinogalactan
1) Boosts the Immune System
Arabinogalactan may have several immune-boosting properties .
Cell studies show that arabinogalactan stimulates components in the immune system, including:
Although some of these – such as TNF-alpha – are inflammatory, a certain level of inflammation is needed to activate immune defense when faced with a threat. Inflammation is dangerous only when it becomes excessive and chronic, such as in autoimmune diseases. And natural killer cells are critical to the immune system; they protect you against infections and cancer .
Animal studies have revealed similar results. In one mouse study, arabinogalactan injections doubled natural killer cells .
Arabinogalactan extracted from the bark of the arjun tree reduces coughing by 54.8% in guinea pigs. This tree, also known as arjuna, is also a well-known Ayurvedic heart tonic .
What does this mean for us humans?
Admittedly, the results in human studies are a little less clear.
On the other hand, one large study of 199 people suffering from the common cold did find clinical benefits. Arabinogalactan supplements reduced cases of the common cold by 23% .
The bottom line?
Arabinogalactan may help if your immune system is weakened, such as when you’re fighting off an infection or if you frequently catch colds. However, healthy individuals may see little to no effect, while those with autoimmune issues are better off avoiding immune-stimulants altogether .
2) Improves Vaccine Response
Vaccines are designed to help our antibodies recognize and eliminate dangerous microorganisms. There are several types of antibodies, but IgG is the most important one for vaccines to work .
We normally see a rise in IgG levels shortly after vaccination. This shows that the immune system has detected the vaccine and is building up its defenses against it .
This is where arabinogalactan comes in.
For instance, a study of 75 people shows that arabinogalactan increases IgG antibodies after a tetanus vaccination .
A similar study in 45 people found that it also increases IgG after a pneumococcal vaccine .
Interestingly enough, the same IgG-boosting effect was not seen with flu shots (the influenza vaccine). It’s not entirely clear why this is. It may be due to influenza being a virus rather than a bacteria [16, 1].
3) Cancer-fighting Potential
Arabinogalactan may have anti-cancer properties.
Studies in cells and animals show potential in a variety of cancer types, including:
On top of that, arabinogalactan can have a synergistic effect with other anti-cancer compounds (both synthetic and natural), including:
- Curcumin 
- Betulin, also found in birch trees 
- Norcantharidin, a synthetic small molecule discovered by a Chinese team of scientists. Interestingly, it is derived from an insect called the blister beetle 
- Platinum 
How do these combinations work?
Research suggests that arabinogalactan helps to target cancer cells and reduces drug toxicity. In other words, arabinogalactan can make other anti-cancer agents more tolerable and effective [21, 24, 22].
4) Protects the Stomach
In addition, arabinogalactan-proteins can block bacteria from attaching to stomach cells. Specifically, they prevented H. pylori from sticking to the stomach lining, which may prevent inflammation and ulcers .
It gets better.
Arabinogalactan can increase the production of butyrate, a fatty acid that is important for gut health. Butyrate can prevent gut toxins from entering the bloodstream and boost your energy use, helping to fight obesity [3, 32].
5) Relieves Allergies
A mouse study found that arabinogalactan reduces airway inflammation and sensitivity to allergens .
It does this by reducing the activity of so-called dendritic cells. These cells are responsible for helping the immune system recognize allergens. But when they become too sensitive, your immune system starts overreacting and triggers allergies .
However, this effect was only seen in arabinogalactan obtained from a certain grass species. The same effect was not seen in arabinogalactan sourced from gum arabic or larch .
6) Prevents Dry Eyes
Interestingly enough, arabinogalactan might help with dry eyes.
One study in rabbits found that an arabinogalactan 5% solution protects against dry spots on the cornea (the transparent front surface of the eye). On top of that, researchers found that the solution also speeds up healing time after an eye injury .
A different study examined these eye effects on a cellular level. They found that arabinogalactan stimulates cell growth in the eye without causing any damage .
7) May Relieve Pain
Arabinogalactan extracted from a tropical fruit called tamarillo may have pain-relieving effects. In a recent study in mice, it reduced inflammation-related pain. Arabinogalactan from tomato mucilage had similar effects in mice. We don’t yet know if birch arabinogalactan also as a natural painkiller as well [38, 39].
8) May Help With Diabetes
Arabinogalactan may help control diabetes as well, but much more research is needed.
In one mouse study examined, arabinogalactan obtained from white-skinned sweet potatoes lowered blood glucose and improved insulin sensitivity. White-skinned sweet potatoes are considered a good dietary choice for diabetics, and arabinogalactan seems to enhance their benefits .
Synergistic Effects with Other Drugs
Researchers are also exploring arabinogalactan’s ability to improve the effects of other drugs.
The chemical structure of arabinogalactan allows it to act as a vehicle that transports drugs to their target .
For example, one rat study examined the effects of an aspirin and arabinogalactan combo in a 1:10 ratio. They found that the combo relieves pain and inflammation at lower doses than pure aspirin. In addition, it is much less toxic to stomach cells .
A very similar study found the same improvements with an ibuprofen and arabinogalactan combination .
But that’s not all.
Researchers are especially interested in synergistic effects with anti-cancer agents. Cancer treatments are often limited by their toxic effects. Arabinogalactan can help deliver cancer drugs directly to cancer cells. This could potentially reduce toxicity and increase effectiveness [21, 24, 22].
Examples of anti-cancer combinations with arabinogalactan include:
- Curcumin for breast cancer 
- Liposomes for liver cancer 
- Norcantharidin for liver cancer 
- Platinum for ascites tumor 
- Betulin for lung cancer 
How Does Arabinogalactan Work?
First, it’s important to note that it is difficult to digest arabinogalactan. It is classified as a dietary fiber because we lack the enzymes to properly break it down.
Instead, arabinogalactan sits in our colon and is slowly fermented by the bacteria there. This fermentation produces short-chain fatty acids (SCFA), such as butyrate, which have a plethora of beneficial effects .
In fact, SCFAs balance different components of the gut immune system; they are fuel for gut cells; they reduce inflammation and help maintain electrolyte and fluid balance .
And there’s more.
Arabinogalactan may also interact with M-cells. These M-cells are part of the so-called gut-associated lymphoid tissue, or to put it simply, the central hub of your gut’s immune system .
One theory is that arabinogalactan molecules stimulate M-cells, which go on to activate T cells, B cells, and other cells of the immune system. This way, gut immunity extends to affect whole-body immunity .
Arabinogalactan Side Effects and Safety
Arabinogalactan is generally considered safe.
About 3% of people experience side effects, which mainly consist of bloating and flatulence [47+].
Long-term toxicity studies in animals have found no safety issues. Human safety studies on arabinogalactan supplements are lacking [47+].
There is also some concern that arabinogalactan may worsen autoimmune disorders. Theoretically, its immune-boosting effects may provoke and increase the symptoms of these disorders. However, there are no documented cases of this occurring.
Little research has been done on arabinogalactan’s potential drug interactions.
However, there are some theoretical interactions to be aware of.
Arabinogalactan has shown synergistic effects with certain drugs. This is a benefit in cancer treatment, but increasing drug effectiveness may be harmful with other types of medication .
Also, arabinogalactan can increase the activity of the immune system. This may be detrimental for people who require immunosuppressive drugs .
Discuss with your doctor about all the medications and supplements you are currently taking to avoid potentially dangerous interactions.
Limitations and Caveats
Research on arabinogalactan has primarily involved animals and cells – very few studies have been done in humans.
More clinical trials are required to properly evaluate effectiveness. Additionally, no clinical trials have looked at the long-term safety risks.
Arabinogalactan supplements are available in powder and capsule form.
Supplement products typically recommend a dose of about 4 grams per day.
The powder is usually mixed with water or juice, but it can be added to food as well [47+].
Reviews & User Experiences
Online reviews of arabinogalactan supplements tend to be mostly positive.
Some users praise the supplements ability to prevent colds and infections. Others say it reduces asthma symptoms and improves digestion.
Negative reviewers usually say they experienced no effect. A few users have also complained of constipation.
Arabinogalactan is a carbohydrate-based compound naturally found in many plants.
Similar to other plant gums, it’s commonly used as a thickening and stabilizing agent.
Arabinogalactan may also have several health benefits, which include:
- Boosting the immune system
- Cancer-fighting potential
- Improving gut health
- Alleviating allergies
- Preventing dry eyes
It is generally considered safe, but no long-term human studies have been done. Common side effects include bloating and flatulence.
The composition of arabinogalactan can vary widely depending on the plant source. For supplements, it may be helpful to pay attention to the source to ensure consistent results.