About the Research Databases

The Wellness Evidence team of doctor consultants selected four of the most respected evidence-based medicine databases that are also particularly useful for wellness-focused research: Natural Standard, The Cochrane Library, PubMed and the TRIP Database.

Please read “Important Things to Know,” including info on each database.

We’ve made researching a particular therapy simple by pre-searching the evidence at each database. (See evidence below.) However, please note that evidence-based medicine relies on a research hierarchy, because not all evidence is created equalLearn more about how the medical experts classify this research.

We’d like to hear from you. If there is a Wellness Evidence discipline you would like to see on these pages, please email us.

Natural Standard

An international research collaboration that systematically reviews (and limits its focus to) scientific evidence on complementary and alternative medicine (CAM). Founded in 2000, Natural Standard assigns a grade to each CAM therapy, reflecting the level of available scientific data for or against the use of each therapy for a specific medical condition.

Natural Standard is subscription-based, and each of the database’s monographs aggregates data from other resources like AMED, CANCERLIT, CINAHL, CISCOM, the Cochrane Library, EMBASE, HerbMed, International Pharmaceutical Abstracts, Medline and NAPRALERT – and 20 additional journals. Data analysis is performed by healthcare professionals conducting clinical work and/or research at academic centers, using standardized instruments pertaining to each monograph section


Tai chi is a system of movements and positions believed to have developed in 12th Century China. Tai chi techniques aim to address the body and mind as an interconnected system and are traditionally believed to have mental and physical health benefits to improve posture, balance, flexibility, and strength.

Many styles of tai chi have developed since the original set of 13 postures. The modern practice of tai chi often includes sequences of slow movements coordinated with deep breathing and mental attention. Specific forms or poses may last from five to 30 minutes. Tai chi is taught in classes or can be practiced alone. Classes often include fewer than 20 people. Instructors guide pupils through movements, encouraging them to keep their bodies stable and upright while shifting weight. A high level of concentration is usually involved, and sessions are intensely focused and quiet. Exercises can also be practiced alone daily for 15 to 20 minutes, often in the morning.

Evidence Table
The grades A-F ascribed to the specific health conditions below have a very specific meaning. i.e., a “C” can still mean evidence of benefit from a small randomized trial, etc. Read about what each grade actually means. Grade
Aging (quality of life in the elderly)
There is good evidence from several studies indicating that tai chi, if practiced regularly, may help improve quality of life in the elderly. Beyond improved balance and the preventive effects against falls, it appears that the practice may improve overall physical functioning and sense of well-being.
Balance and strength maintenance
Early research suggests that tai chi practice may improve balance and maintain strength. These benefits may be similar to other forms of exercise. Additional research is necessary before a firm conclusion can be reached.
Body fat reducer (body fat redistribution in the elderly)
There is not enough scientific evidence to recommend the use of tai chi to change body fat distribution in the elderly.
Breast cancer
Tai chi chuan has been studied in breast cancer patients to improve functional capacity (specifically aerobic capacity, muscular strength, and flexibility). Larger studies are needed to make a firm recommendation.
Cardiovascular disease
There is evidence that suggests that tai chi decreases blood pressure and cholesterol as well as enhances quality of life in patients with chronic heart failure. Most studies have used elderly Chinese patients as their population. Additional research is needed before a firm conclusion can be drawn.
Cardiovascular rehabilitation
Tai chi, as a complement to existing exercise interventions, can be utilized for low and intermediate risk patients. Although promising, more study is needed to make a firm recommendation.
Chickenpox, shingles (varicella zoster)
A small trial showed that treatment with tai chi might increase immunity to the virus that causes shingles. This may suggest the use of tai chi in the prevention of chickenpox and shingles, but further well-designed large studies must be done before a recommendation can be made.
Chronic pain
There is a lack of scientific evidence to conclude that tai chi is effective for chronic pain conditions. Further research is needed in this area.
Cochleovestibular impairment (vestibulopathy)
Early scientific evidence suggests that tai chi may be helpful as an adjunct treatment to regular vestibular rehabilitation regimes. Tai chi may improve body stability and footfall stability. More studies are needed.
Preliminary research suggests that tai chi may alleviate depression, anger, and fatigue. Better studies are needed before conclusions can be drawn.
Tai chi has been suggested as a possible therapy for improving body composition and improving blood sugar regulation in diabetics. Early results are mixed, and additional study is needed. Tai chi is not recommended over current standard of care for diabetes control.
Exercise capacity
Several studies suggest that tai chi is a form of aerobic exercise that can improve aerobic capacity. In particular, benefit has been reported with the classical Yang style.
Fall prevention (elderly)
Several studies have examined the effects of regular tai chi practice on balance and falling risk in the elderly. Results are not consistent, and many studies have been poorly designed. It is not clear if tai chi is safer or more effective than other forms of exercise in older individuals. Better research is needed before a recommendation can be made.
Tai chi may aid quality of life in fibromyalgia patients, but additional study is needed to make a strong recommendation.
High blood pressure
Early study shows that tai chi may help patients with high blood pressure to reduce blood pressure, cholesterol, and anxiety.
Immune stimulant
Tai chi may increase the body’s immune response in older adults. For example, patients receiving varicella vaccines and who practiced tai chi showed increased immune responses. Although early study is promising, more study is needed.
Lung function (after lung removal)
Tai chi practice may help improve lung function, activity capacity, and quality of life of patients after lobectomy (lung removal usually due to cancer). More study is needed in this area.
Women but not men may experience improved mood as a result of tai chi practice. Additional research is needed in this area.
A small trial in women with osteoarthritis reported that treatment with tai chi significantly decreased pain and stiffness compared with a sedentary lifestyle. Women in the tai chi group also reported fewer perceptions of difficulties in physical functioning.
Preliminary research suggests that tai chi may be beneficial in delaying early bone loss in postmenopausal women. Additional evidence and long-term follow-up is needed to confirm these results.
Parkinson’s disease
Community-based fitness programs, which include tai chi classes, may improve balance in Parkinson’s patients and motivate patients to participate in routine exercise.
Quality of life (HIV)
Tai chi has been studied in individuals living with various stages of HIV. Preliminary study shows that tai chi may be helpful for stress and improving quality of life, but additional research is needed before a recommendation can be made.
Rheumatoid arthritis
There is not enough scientific evidence showing that tai chi reduces rheumatoid arthritis symptoms, although tai chi may help improve range of motion of the lower extremities.
Sleep disorders
Tai chi may lead to improved sleep quality in older adults with sleep disorders. More studies are needed before definitive recommendations can be made.
Tai chi may reduce stress in various populations of people, including HIV patients.
Stroke recovery
Tai chi may benefit social and general functioning in stroke rehab patients but may not be as effective as physiotherapy for balance and speed of walking.
Tension headaches
Early study suggests that tai chi practice may be effective in reducing tension headache impact and may also be effective in improving perceptions of some aspects of physical and mental health.
Traumatic brain injury
Based on a small study, tai chi may provide short-term benefits after traumatic brain injury; however, long-term studies are needed.

In traditional Chinese medicine, illness may be viewed as the result of imbalance between two opposing life forces: yin and yang. The practice of tai chi aims to reestablish balance creating harmony between body and mind and between the individual and the outside world. It is said that in the 13th Century, Taoist priest Chang San Fang observed a crane fighting with a snake and compared their movements to yin and yang. Some techniques of tai chi were based on movements mimicking these animals.

In modern times, tai chi is a physical exercise that, when practiced regularly, may increase muscle strength. Preliminary scientific evidence suggests that better cardiovascular health, coordination, and balance may occur from regular tai chi practice.


The below uses are based on tradition, scientific theories, or limited research. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. There may be other proposed uses that are not listed below.

Ankylosing spondylitis, anxiety, asthma, attention deficit hyperactivity disorder (ADHD), bronchitis, chronic lung conditions, circulation problems, congestive heart failure, coronary artery disease, emphysema, fibromyalgia, gastritis, gout, hemiplegia, hemophilia, improving concentration, increasing energy, kidney disorders, low back pain, lowering heart rate, multiple sclerosis (MS), neurast


Many complementary techniques are practiced by healthcare professionals with formal training, in accordance with the standards of national organizations. However, this is not universally the case, and adverse effects are possible. Due to limited research, in some cases only limited safety information is available.

Adverse effects of tai chi are rarely reported and may include sore muscles or sprains. Tai chi should be avoided by people with severe osteoporosis or joint problems, acute back pain, sprains, or fractures. Advancing too quickly while studying tai chi may increase the risk of injury.

Tai chi instructors sometimes recommend that practice be avoided during active infections, right after a meal, or when very tired. Some believe that visualization of energy flow below the waist during menstruation may increase menstrual bleeding. Straining downwards or holding low postures should be avoided during pregnancy and by people with inguinal hernias. Some tai chi practitioners believe that practicing for too long or using too much intention may direct the flow of chi (qi) inappropriately, possibly resulting in physical or emotional illness.

Tai chi should not be used as a substitute for more proven therapies for potentially serious conditions. Individuals should consult a qualified healthcare professional if they experience dizziness, shortness of breath, chest pain, headache, or severe pain while practicing tai chi.


This information is based on a professional level monograph edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com): William Collinge, PhD, MPH (Collinge & Associates); Dawn Costa, BA, BS (Natural Standard Research Collaboration); Nicole Giese, MS (Natural Standard Research Collaboration); David Lee, PharmD (Massachusetts College of Pharmacy); Katie Nummy, BS (Northeastern University); Shaina Tanguay-Colucci, BS (Natural Standard Research Collaboration); Catherine Ulbricht, PharmD (Massachusetts General Hospital); Wendy Weissner, BA (Natural Standard Research Collaboration).


Natural Standard developed the above evidence-based information based on a thorough systematic review of the available scientific articles. Selected references are listed below.

  1. Abbott RB, Hui KK, Hays RD, et al. A Randomized Controlled Trial of Tai Chi for Tension Headaches. Evid Based Complement Alternat Med 2007 Mar;4(1):107-113.
  2. Faber MJ, Bosscher RJ, Chin A, et al. Effects of exercise programs on falls and mobility in frail and pre-frail older adults: A multicenter randomized controlled trial. Arch Phys Med Rehabil 2006 Jul;87(7):885-96.
  3. Galantino ML, Shepard K, Krafft L, et al. The effect of group aerobic exercise and t’ai chi on functional outcomes and quality of life for persons living with acquired immunodeficiency syndrome. J Altern Complement Med 2005 Dec;11(6):1085-92.
  4. Gemmell C, Leathem JM. A study investigating the effects of Tai Chi Chuan: individuals with traumatic brain injury compared to controls. Brain Inj 2006 Feb;20(2):151-6.
  5. Irwin MR, Olmstead R, Oxman MN. Augmenting immune responses to varicella zoster virus in older adults: a randomized, controlled trial of Tai Chi. J Am Geriatr Soc 2007 Apr;55(4):511-7.
  6. Lee MS, Pittler MH, Ernst E. Tai chi for osteoarthritis: a systematic review. Clin Rheumatol 2008 Feb;27(2):211-8.
  7. Lee MS, Pittler MH, Ernst E. Tai chi for rheumatoid arthritis: systematic review. Rheumatology (Oxford) 2007 Nov;46(11):1648-51.
  8. Lee MS, Pittler MH, Ernst E. Is Tai Chi an effective adjunct in cancer care? A systematic review of controlled clinical trials. Support Care Cancer 2007 Jun;15(6):597-601.
  9. Li F, Fisher KJ, Harmer P, et al. Tai chi and self-rated quality of sleep and daytime sleepiness in older adults: a randomized controlled trial. J Am Geriatr Soc 2004;52(6):892-900.
  10. Li F, Harmer P, Fisher KJ, et al. Tai Chi and fall reductions in older adults: a randomized controlled trial. J Gerontol A Biol Sci Med Sci 2005;60(2):187-194.
  11. Maciaszek J, Osinski W, Szeklicki R, et al. Effect of Tai Chi on body balance: randomized controlled trial in men with osteopenia or osteoporosis. Am J Chin Med 2007;35(1):1-9.
  12. Taylor-Piliae RE, Haskell WL, Stotts NA, et al. Improvement in balance, strength, and flexibility after 12 weeks of Tai chi exercise in ethnic Chinese adults with cardiovascular disease risk factors. Altern Ther Health Med 2006 Mar-Apr;12(2):50-8.
  13. Thomas GN, Hong AW, Tomlinson B, et al. Effects of Tai Chi and resistance training on cardiovascular risk factors in elderly Chinese subjects: a 12-month longitudinal, randomized, controlled intervention study. Clin Endocrinol (Oxf) 2005 Dec;63(6):663-9.
  14. Voukelatos A, Cumming RG, Lord SR, et al. A randomized, controlled trial of tai chi for the prevention of falls: the Central Sydney tai chi trial. J Am Geriatr Soc 2007 Aug;55(8):1185-91.
  15. Yeh GY, Wood MJ, Lorell BH, et al. Effects of tai chi mind-body movement therapy on functional status and exercise capacity in patients with chronic heart failure: a randomized controlled trial. Am J Med 10-15-2004;117(8):541-548.


British epidemiologist Archie Cochrane is regarded as the originator of the Evidence-Based Medicine concept (in the 1950s). And the Cochrane Library is a collection of very high-quality medical databases, which have, at their core, the Cochrane Reviews, systematic reviews and meta-analyses which summarize and interpret the results of well-conducted, randomized controlled trials… the ‘gold standard’ in Evidence-Based Medicine.

The Cochrane Library is a subscription-based database but offers free access to abstracts.


A service of the U.S. National Library of Medicine, PubMed was released in 1996 as a free digital archive of references and abstracts on life sciences and biomedical topics. PubMed comprises 20-million-plus citations for biomedical literature from MEDLINE, life science journals and online books from around the world. Some 11.5 million articles are listed with their abstract and 3.1 million articles are available in full-text for free.


The TRIP Database, launched in 1997, is a search engine designed to allow clinicians to quickly find answers to their medical questions using the best available evidence. Trip’s founders realized medical professionals were being forced to perform time-consuming searches at multiple websites to get at the most relevant information. So, they designed TRIP as a meta-search engine, allowing users to both simultaneously search thousands of databases, medical publications and resources, as well as easily filter the results: limiting searches to the most stringent, highest-quality medical evidence or expanding them to include results like patient information, news articles, etc.