Rehmannia has been used in traditional Chinese medicine for thousands of years, but modern research on its potential benefits is relatively scarce. It has shown promise for anemia and kidney function; what other benefits might it have? Read on to find out. What is Rehmannia?
Rehmannia glutinosa is a flowering plant found in central China . It’s sometimes called Chinese foxglove because it looks somewhat like a foxglove flower, though the two aren’t actually related [ 1 ].
The roots of this plant have been used in Traditional Chinese and Korean Medicine for over 2,000 years [ 2 , 3 ].
According to the traditional outlook, the harmony of opposite, but complementary, forces – yin and yang – underlies good health. Rehmannia is thought to help with yin energy imbalances. It is traditionally used to fight bacterial infections, as a tonic, and for a variety of conditions associated with inflammation, like asthma and arthritis [ 4 , 5 , 1 ].
Rehmannia is also often combined with other herbs to remedy “yin deficiency”. For example, it’s one of the six ingredients in a popular Chinese herbal product called Rehmannia Six Formula and one of the seven ingredients in the traditional kidney-nourishing herbal formulation Yukmi-jihang-tang. It is also included in widely-used formulations, such as Liuwei Dihuang Pills [ 6 , 3 , 7 ]. Snapshot
May improve anemia by supporting blood cell production
May support kidney function
Early evidence of mood, blood sugar, and bone support
Unclear which active components are responsible for the benefits
Researched and often used in multi-herb formulations
Weak or low-quality evidence for many benefits
Side effects largely unknown
Although the above-ground parts are sometimes used, herbal remedies are much more often prepared from the orange roots of this plant [ 8 , 9 ].
Depending on how the roots are prepared, they are called [ 10 ]: Xian-Di-Huang (for the fresh root)
Sheng-Di-Huang (for baked roots)
Shu-Di-Huang (for steamed roots) in Chinese
Over 70 active compounds have been found in Rehmannia , including amino acids , simple and complex sugars , vitamins , and plant-specific compounds. Their composition in extracts mostly varies according to the plant species and the root preparation method [ 5 , 9 ].
One of the most well-known plant-specific compounds in Rehmannia is called catalpol , which accounts for 0.3-0.5% of the dried root. Catalpol is an iridoid glycoside, a group of molecules plants create to defend against predators. They also have a range of health effects in humans [ 1 , 11, 12 ].
Catalpol is likely responsible for the plant’s sugar-lowering, inflammation-fighting, and immune-balancing effects in cells and animals. Rehmannia also contains rehmapicrogenin, a strong anti-inflammatory. This compound that helps deactivate one of the most important inflammation-triggering factors in cells ( NF-κB ) [ 13 , 14 ]. Mechanism of Effect
According to some researchers, Rehmannia may improve stress resilience and mood by enhancing the body’s antioxidant defense [ 15 ].
Certain complex sugars in Rehmannia may target the hippocampus, a part of the brain that plays an important role in memory and mood. Catalpol might also help brain cells resist damage. As a result, the plant’s compounds are currently being investigated for their effect on dementia and anxiety [ 16 , 17 , 11 ].
Rehmannia also affects energy use and is under investigation in people with diabetes and insulin resistance . Sugar extracts of this plant increased insulin production in mice and catalpol lowered glucose levels in diabetic rats. Catalpol also increases the secretion of endorphins from the adrenal gland, which helps transport glucose from the blood into the muscles [ 18 , 19 , 20 , 21 ].Traditional practitioners claim that Rehmannia can reverse anemia, and some evidence suggests that it may protect the parts of the bone marrow that make red blood cells . Nourishing the blood is one of its main traditional indications, while anemia is considered to be a sign of yin deficiency. As such, early sickle-cell anemia clinical trials are in progress with a compound isolated from the steamed roots, but the results aren’t in yet [ 22 , 23 ].In cell studies, Rehmannia helped alleviate inflammation by sponging up free radicals – highly reactive compounds that can damage cells – as well as by causing immune cells to secrete fewer inflammatory signaling molecules. Importantly, it also blocked the expression of inflammatory genes in these cell studies. Reducing inflammation is beneficial in many conditions, but researchers are currently looking at its application in bone and kidney health [ 14 , 24 , 25 , 26 , 27 , 28 ].What’s more, this herb caused kidney cells to express fewer receptors that drive high blood pressure. According to some researchers, if this effect translates to the human body, it could make it useful for protecting the kidneys that are already strained due to other diseases, like diabetes. Dried and steamed roots reduce renin in animals, thereby lowering blood pressure and reducing kidney damage [ 28 , 29 ]. Potential Benefits Rehmannia supplements have not been approved by the FDA for medical use and generally lack solid clinical research. Regulations set manufacturing standards for them but don’t guarantee that they’re safe or effective. Speak with your doctor before supplementing. 1) Anemia Aplastic anemia is a rare disease in which the body stops making enough blood cells due to bone marrow damage. In a clinical study of 34 people with this disease, Rehmannia extract added to standard treatment sped up symptom remission better than standard treatment alone [ 30 ].A combination of traditional medicines, including Rehmannia , had promising effects in another trial of 64 people with the same type of anemia. An integrative medicine approach could protect the bone marrow and red blood cells and reduce inflammation. As a result, 12 participants had blood markers comparable to healthy people [ 23 ]. Rehmannia and its extracts, alone and in combination with other supplements, also improved anemia in […]