You’ll find garlic, garlic powder, and garlic oil in dishes made by civilizations throughout history, including the ancient Chinese, Greeks, Egyptians, Japanese, and Romans.
Perhaps these ancient cultures knew something about the bulb beyond enjoying its flavor.
Though the National Center for Complementary and Integrative Health (NCCIH) says it’s not a surefire remedy for the common cold or an all-in-one immune system booster,
research has revealed some interesting mechanisms through which garlic supports immune health.
Garlic Increases Immune Cell Activity in Rodents and Chickens
Though the research is still ongoing, there is some evidence that garlic interacts with different types of immune cells. Research found that raw garlic essential oils and specific compounds in garlic called polysaccharides improved several indicators of immune health in rodents and chickens.
A few of the immune cells included:
- Immunoglobulins (IgG): These proteins help the immune system identify and attack pathogens. In the studies, garlic essential oils returned IgG levels to normal.
- T-cell subtype CD4+: T-cells coordinate immune responses, and researchers found garlic restored levels of CD4+ T-cells in rats.
- Lymphocytes: Lymphocytes are white blood cells that fight infections. Polysaccharides in garlic improved how these multiplied.
- Interferon-Y and interleukin-2: These cells help control immune activity — interferon-Y fights viruses, while interleukin-2 supports T-cell growth. Those same polysaccharides in garlic boosted levels of both in broiler chickens.
- Antibody titer: Researchers found that garlic helped the antibody titer increase. This means more antibodies were in the blood, ready to target specific bacteria or viruses.
Though those findings are impressive, the research doesn’t show how these immune cell changes would impact how humans could counter disease. More research would help scientists understand garlic’s direct impact on the immune system.
Garlic May Enhance Blood Flow
Garlic may positively affect how blood moves through the body, which could indirectly benefit immune health. But studies have not shown a direct link between garlic, blood flow, and better immune health.
One study involving two groups of people, one that took a garlic powder tablet and another that took a placebo containing cornstarch found that the garlic powder group had better function in the inner layer of the blood vessels, known as the endothelium.
The endothelium helps to control blood flow, per Cleveland Clinic.
And even though research is still conflicting, the NCCIH notes that the most robust evidence for garlic’s beneficial effects on the body lies in its ability to improve blood cholesterol levels.
They state that the effects are limited, though, and take around eight weeks to show improvement.
Garlic May Aid Zinc Absorption for an Immune Boost
Some compounds in garlic may help the body absorb zinc more efficiently. A study compared how well mice absorbed lab-made zinc salts versus a combination of zinc and garlic polysaccharides.
The combination supplement had better bioavailability, meaning that the mice’s bodies were able to use the zinc more effectively and showed better effects in response to supplementation.
According to Mayo Clinic, zinc helps the immune system
by supporting the growth of immune cells like lymphocytes, neutrophils, and macrophages, and improving their function.
Reduced immunity may be a symptom of zinc deficiency, which is most common in people with nutrient absorption issues.
While more research in humans is necessary to confirm whether combining zinc with garlic would be genuinely beneficial for immunity, people may be able to absorb these supplements more quickly to correct their levels.
Garlic Helps Manage Stress for Better Immunity
According to Cleveland Clinic, chronic stress can impact the immune system by reducing how many lymphocytes move around in the bloodstream.
This means that you might have a higher risk of viruses and other infections.
While many measures support stress management, some supplements can reduce how your body reacts to stress. A 2019 study on mice found that 500 milligrams per kilogram of body weight of raw garlic extract balanced stress-induced changes in brain chemicals, reduced stress hormones, and improved the action of antioxidants that protect cells from damage.
Though you unfortunately can’t take research about mice and apply it to humans, these findings provided an interesting foundation for future research.
How to Use Garlic for Immunity
Gaining immunity from garlic isn’t as simple as wearing fresh cloves around your neck, though we wish it were. Currently, no medical guidelines suggest a dosage of garlic that can help you access its potential immune system benefits, because little significant evidence directly supports its use as a barrier to disease.
On the other hand, it’s known that garlic’s active compound, allicin, is behind many of garlic’s suggested benefits.
The authors of a 2018 study explained that allicin usually forms in the gut after you eat garlic, so working out exactly how much you get — and the best way to get it — can be challenging.
The body was most efficient at using garlic in the form of powder capsules and tablets that don’t reach the gut, known as non-enteric tablets.
Cooked or pickled garlic also released more allicin than the researchers expected.
Garlic Usage: Potential Risks and Precautions
Garlic is generally safe in the amount you’d usually throw into pasta or a stir-fry, per the NCCIH.
But side effects might include:
These side effects may be more evident after you eat raw garlic.
People who take blood thinning medications like Warfarin or will soon be receiving surgery should let their physician know if they plan on using garlic supplements, as garlic might increase a person’s risk of bleeding.
Garlic supplements’ effects during pregnancy and breastfeeding are not clear. They may also interact with certain medications like an HIV drug called saquinavir or other dietary supplements.
The Takeaway
Garlic is generally safe (and delicious), but research into its effects on immunity is limited and its benefits are thought to be mostly indirect. Any steps to improve immune health should be part of a varied, nutritious diet high in fruits and vegetables and a balanced lifestyle involving regular exercise, a robust sleep schedule, and stress management.
Consider speaking to a healthcare professional if you’re considering taking a supplement to support immune health.
