An extract from larch trees offers powerful protection against colds and flu.

A special type of fiber from larch trees, larch arabinogalactan, has been growing in popularity as a supplement for improving immunity and protecting against colds and flu. Although its exact mechanism isn’t fully understood, studies show that it improves the body’s ability to defend itself when pathogens strike, helping to prevent and fight off a variety of infections.


Preventing Colds

A German study found that when compared with a placebo, a specific larch arabinogalactan ingredient (ResistAid) reduced the number of colds by 23 percent in a group of people who had suffered from at least three colds in the previous six months. Researchers gave a total of 199 people either a 4.5-gram daily dose of the supplement or a placebo for 12 weeks. Participants, who ranged in age from 18 to 70, kept diaries to record symptoms, and doctors confirmed the incidence or absence of colds.

After four months, the researchers concluded that “larch arabinogalactan increased the body’s potential to defend against common cold infection.” The study was published in the journal Current Medical Research & Opinion.

Enhancing Natural Defenses

To test the effect of the same larch ingredient on immune response, two separate studies examined how the supplement influences reactions to vaccines. While it would not be ethical to infect people with a disease in order to test a preventive supplement, vaccines enable researchers to measure immune response objectively without making people ill.

With any vaccine, we receive a minute amount of a pathogen in order to trigger production of our own antibodies, which are designed to defeat that particular bug. Then, should we face a real infection, the immune system is prepared to fight it off. This research showed that larch measurably enhances immune response.

In one study, published in Nutrition Journal, 45 healthy people received a pneumonia vaccine and either 4.5 grams of larch or a placebo. Those taking larch built up significantly stronger defenses against pneumonia.

The other study, published in the Journal of the American College of Nutrition, compared the effects of a tetanus vaccine along with either larch or a placebo among 75 healthy people between the ages of 18 and 61. Compared with the placebo, 1.5 grams of larch, taken daily, produced significantly stronger natural defenses against tetanus.

In both studies, larch supplements were taken for 30 days before receiving a vaccination. This seemed to prepare the immune system for a more effective response to the vaccine.

Other Promising Research

Preliminary research shows that larch has a number of other therapeutic qualities. Lab and animal studies found that it can inhibit the spread of cancerous cells, especially in the liver, but it hasn’t yet been tested in human cancer trials.

Since the 1990s, there have been reports that larch can reduce the incidence and severity of ear infections in children, but because safety tests of the supplement among children haven’t been published, products are typically recommended only for adults.

The native Cree people of northern Quebec, in Canada, have traditionally used larch to treat diabetes, and researchers at Quebec’s Université de Montréal have examined components of larch that could be therapeutic. In a lab study, published in the Journal of Ethnopharmacology, scientists found that larch naturally contains several substances known to have antidiabetic properties.

As research continues, we may discover many more uses for larch. Meanwhile, it’s available in plenty of products to enhance our ability to stay healthy year-round.

How To Use Larch

The supplement works best when taken daily to enhance natural defenses. Studies have tested 1.5 and 4.5 grams of a proprietary larch arabinogalactan ingredient, ResistAid, which is found in a variety of supplements for immune health. Combination immune formulas may contain smaller amounts of ResistAid or other larch ingredients along with synergistic immune-enhancing substances. Larch is also found in some greens powders. Because formulas vary, follow label directions for dosages.


If you’re interested in using larch or any other natural remedy as a treatment for an existing condition, or to prevent children’s ear infections, consult a naturopathic doctor beforehand. Your local health food store may be familiar with practitioners in your area.

Good Buys:


ECLECTIC INSTITUTE Larix powder features a water-soluble arabinogalactan polysaccharide from the Western larch tree—just mix with water or juice.


NATURE’S PLUS Herbal Actives ARA-Larix Olive Leaf combines two ingredients known to support immunity—pure arabinogalactans (Larixoccidentalis) and olive leaf.


VIBRANT HEALTH Immune Defense is formulated with potent immune supporters including 250 mg of ImmunEnhancer (larch arabinogalactans).

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