New research has shown that a relatively small daily amount of dried shiitake mushroom (5 grams of dried mushroom, which is the equivalent of 1-ounce fresh mushroom or less than one large shiitake mushroom) can provide measurable anti-inflammatory benefits. This finding is great news for anyone who is interested in bringing small amounts of shiitake mushrooms into his or her diet, without necessarily making it any sort of dietary focus. Consumption of these small amounts of shiitake mushroom by 50 study participants lowered blood levels of the inflammatory messaging molecule MIP-1alpha (macrophage inflammatory protein 1alpha) and increased blood levels of anti-inflammatory molecules including interleukins 4, 10, and 1alpha (IL-4, IL-10, and IL-1a). This study outcome is not surprising since shiitake mushrooms have an extensive track record as an anti-inflammatory food. But it is great to see these benefits coming from dietary intake of shiitake mushrooms in a whole food form, and more importantly, in a very "do-able" intake amount. Just how easy would it be to consume this amount of shiitake mushrooms? In our World's Healthiest Foods Meal Plan, we include 3/4 cup of fresh sliced and sautéed shiitake mushrooms in our Day 3 dinner alone. All by itself, this amount comes close to matching the shiitake mushroom intake that provided participants with these anti-inflammatory benefits.
Researchers are getting closer and closer to understanding the biotin content of shiitake mushrooms, and this advance in understanding should eventually pay real dividends for our health. At WHFoods, we don't provide any data values for biotin in shiitake mushrooms (or in crimini mushrooms) due to the scientific difficulties in measuring biotin levels. However, we are confident that shiitake and most other commonly eaten mushrooms provide very valuable amounts of biotin! So we are excited to see new studies about proteins in shiitake mushrooms called lentiavidins. You might recognize the "avidins" part of this name from research on egg whites. Avidins are egg-white proteins that can bind together with biotin. In the case of shiitake, researchers have added the designation "lenti"—from the shiitake genus Lentinula—to come up with the new protein name, "lentiavidins." Thanks to recent research, we now know that lentiavidins are unique proteins in shiitake mushrooms that can bind together with biotin. What we don't know is how these lentiavidins affect the retention of biotin in shiitake or the bioavailability of biotin from shiitake. But researchers are getting closer to answers here, and we view this research as providing additional evidence about the role of shiitake mushrooms are likely to play in providing us with important amounts of this B-complex vitamin.
At WHFoods, shiitake mushrooms are our 4th best source of copper. (Our top three sources for this antioxidant mineral are sesame seeds, cashew nuts, and soybeans.) Researchers now know that a key enzyme found in shiitake mushrooms—called laccase—requires four atoms of copper to function properly. As a result of its laccase enzyme content, shiitake provides us with 650 micrograms of copper (0.65 milligrams) in a serving size of ½ cup cooked. Since our WHFoods recommended daily intake level for copper is 900 micrograms (0.9 milligrams), about 72% of daily copper intake can be obtained from a single serving of shiitake mushrooms.
We are seeing an increasing level of research interest in one unique alkaloid found in shiitake mushrooms, namely, eritadenine. When compared to commonly eaten mushrooms like crimini and reishi, shiitake mushrooms appears to contain significantly higher amounts of eritadenine. Much of the interest in this phytonutrient has been focused on its ability to inhibit activity of an enzyme called angiotensin-converting enzyme (ACE). Because ACE activity results in a constricting of our blood vessels, inhibition of ACE can help prevent unwanted blood vessel constriction. By preventing unwanted constriction, our blood vessels can keep a wider diameter and this wider diameter allows the pressure on our blood to stay within a normal range. In short: what we are looking at here is a unique nutrient in shiitake mushrooms that appears to increase our chances for better blood pressure regulation.
A variety of different studies on the health benefits of shiitake mushrooms have converged on a special group of carbohydrate-related molecules called glucans. Glucans are polysaccharides (structures comprised of linked sugars) that are found in many different foods. However, shiitake mushrooms are unusual in containing not only a large amount of total glucans but also a large amount of one specific glucan called beta-glucan. Because these glucans cannot be broken down by enzymes in our digestive tract, they pass undigested all the way through to our large intestine where they help support growth of desirable bacteria in our digestive tract. This result earns shiitake mushrooms the right to be called a health-supportive food. But perhaps more importantly, beta-glucans also provide support for a wide variety of body systems, including our immune system, antioxidant system, and our endocrine system. Because beta-glucans can bind onto certain receptors on our immune cells, they can help support immune system function. These polysaccharides can also function as antioxidants and have been shown to have free radical scavenging activity. In addition, beta-glucan intake has been linked to better regulation of our blood sugar and insulin levels. What we are left with here is a category of nutrient intake—polysaccharides—that we don't usually associate with such a wide range of potential health benefits. But research on shiitake mushrooms is convincing us to pay more attention to this carb-related group in shiitake and other mushrooms.