Researchers tested two types of shiitake mushrooms to see if they’re safe to eat and if they have health benefits. They grew human cancer cells in the lab and exposed them to mushroom extracts, finding that one type (DMRO-356) slowed cancer cell growth better than the other. They also gave rats very large doses of both mushroom types for up to 4 weeks and found no harmful effects. The study suggests shiitake mushrooms are safe to use in food and supplements, and they might help support immune health and cancer prevention, though more research in living organisms is needed to confirm these benefits.

The Quick Take

  • What they studied: Whether two different strains of shiitake mushrooms are safe to eat and whether they can slow the growth of cancer cells
  • Who participated: Laboratory tests used human cancer cells (cervical and breast cancer cells) and rats that received mushroom extracts at very high doses
  • Key finding: One shiitake strain (DMRO-356) slowed cancer cell growth in lab tests better than the other strain, and both mushroom types were safe in rats even at very high doses with no harmful side effects observed
  • What it means for you: Shiitake mushrooms appear to be safe for regular consumption in food and supplements. One strain shows more promise for potential cancer-fighting properties, but more research in humans is needed before we can say it actually prevents or treats cancer

The Research Details

Scientists conducted two types of experiments. First, they performed laboratory tests by growing human cancer cells and exposing them to shiitake mushroom extracts to see if the mushrooms could slow cell growth. They used two different testing methods (MTT and LDH assays) to measure how the cancer cells responded. Second, they conducted animal safety tests by giving rats extremely high doses of both mushroom strains (5000 mg per kilogram of body weight) and watched them for 2-4 weeks to check for any harmful effects. They also measured the amount of beta-glucan, a beneficial compound found in mushrooms, in each strain.

This two-step approach is important because it first shows whether shiitake mushrooms have potential anti-cancer properties in controlled lab conditions, and then confirms they won’t cause harm if people consume them regularly. Testing at very high doses in animals helps ensure safety margins for human use.

The study used established scientific methods and published results in a reputable journal (Scientific Reports). However, the sample size for animal testing wasn’t specified, and the lab tests used cancer cells rather than testing in living humans. The very high doses given to rats may not reflect typical human consumption amounts.

What the Results Show

One shiitake strain (DMRO-356) showed stronger effects at slowing cancer cell growth compared to the other strain (DMRO-34) in laboratory tests. Both strains contained beneficial compounds called beta-glucans. When rats received very high doses of both mushroom strains for up to 28 days, they showed no signs of poisoning or harmful effects, suggesting the mushrooms are well-tolerated by the body. The researchers found no observable adverse effects (NOAEL) at the tested dose, which is a scientific way of saying the highest dose tested caused no harm.

The study identified and measured the beta-glucan content in both mushroom strains, which is important because beta-glucans are known to support immune function. The fact that both strains were safe even at extremely high doses suggests a wide safety margin for normal food consumption.

This research builds on existing knowledge that medicinal mushrooms can have health benefits. Previous studies have suggested shiitake mushrooms support immune health, and this study adds evidence that they’re safe for regular use while also showing potential anti-cancer properties in lab conditions.

The study only tested mushroom effects on cancer cells in laboratory dishes, not in living humans. The animal tests used very high doses that are much larger than people would normally eat. The research doesn’t prove that eating shiitake mushrooms will prevent or treat cancer in people—it only shows promise in early-stage testing. More research directly in humans is needed to confirm health benefits.

The Bottom Line

Based on this research, shiitake mushrooms appear safe to include in your regular diet as food or supplements (moderate confidence). The evidence suggests they may support immune health and potentially help with cancer prevention strategies, but they should not be used as a replacement for proven cancer treatments (low to moderate confidence for cancer-specific claims). Consult with a healthcare provider before using mushroom supplements if you’re taking medications or have health conditions.

People interested in natural immune support, those looking to add functional foods to their diet, and individuals exploring complementary approaches to cancer prevention should find this relevant. People with mushroom allergies or those taking blood-thinning medications should consult their doctor first. This research is not yet ready to guide treatment decisions for people with existing cancer.

Immune support benefits from regular mushroom consumption may take several weeks to months to notice. Cancer prevention is a long-term strategy, not something with immediate effects. More research is needed to establish realistic timelines for health benefits in humans.

Want to Apply This Research?

  • Track weekly shiitake mushroom consumption (servings or grams) and note any changes in energy levels, immune health markers (like frequency of colds), or general wellness over 8-12 weeks
  • Add one serving of shiitake mushrooms to your diet 2-3 times per week through cooking, supplements, or functional food products, and log this in your nutrition tracker to build consistency
  • Monitor overall wellness metrics monthly including energy levels, immune function (illness frequency), and digestive health. Track which mushroom products you use and any noticeable effects to identify what works best for your body

This research is preliminary laboratory and animal testing, not human clinical trials. Shiitake mushrooms should not be used as a treatment or cure for cancer or any disease. Always consult with your healthcare provider before starting mushroom supplements, especially if you have existing health conditions, take medications, or are undergoing cancer treatment. This information is for educational purposes only and does not replace professional medical advice. Pregnant and nursing women should consult their doctor before using mushroom supplements.