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


Various forms of meditation have been practiced for thousands of years throughout the world, with many techniques originating in spiritual traditions, particularly in Eastern philosophical and religious practices. In modern times, numerous meditation types are in use, often outside of their original religious and cultural contexts.

The definition of meditation is variable. A classic definition of meditation is the deliberate self-regulation of attention through which the stream of consciousness is temporarily suspended. A common goal is to attain a state of “thoughtless awareness” of sensations and mental activities occurring at the present moment. However, meditation is often popularly perceived as any activity through which a person’s attention is focused on a repetitious thought or word. Meditation generally does not involve suggestion, autosuggestion, or trance. Techniques that make use of constant repetition of syllables, visualizations, or other thought forms, but do not achieve thoughtless awareness are sometimes described as being “quasi-meditative.” There are many forms and sub-types of meditation or “quasi meditation,” and several techniques are described below.

Mindfulness is an approach in which attention is focused on a physical sensation (such as the breath). When thoughts intrude, the individual returns to the focus. Attention is placed on the present moment, rather than on the future or past. This technique may involve a “body scan,” in which one focuses on the body from head to feet, concentrating on areas of pain or illness. This is usually performed while lying down. Regular practice is suggested to enhance self-awareness.

Analytical meditation differs from other forms in that the practitioner does not repeat a word over and over, but rather strives to comprehend the deeper meaning of the object of focus. Guided meditation or guided imagery is a technique that directs the imagination towards a conscious goal. Yoga nidra or yogic “sleep” is considered to be a form of guided meditation.

Breath meditation involves focusing on the process of inhaling and exhaling. Deep breathing exercises taught in childbirth classes are a variation of this form. Counting while breathing may provide a meditative focus.

Visualization involves focusing on a specific place or situation. Walking meditation or kinhin is a Zen Buddhist form of movement meditation in which attention is focused on the feeling of the earth beneath the feet. Sitting meditation is similarly practiced. “Naming” consists of giving a name to physical sensations associated with particular emotions in order to become more self-aware. Numerous other variations and subtypes of meditation exist. Meditation is traditionally distinguished from relaxation based on the state of thoughtless awareness that is said to occur during meditation.

Meditation is generally practiced in a quiet environment and in a comfortable position. Sessions vary in length and in number of times practiced daily. It is often recommended to meditate at the same time(s) each day.

Some organized religions and professional organizations have their own specific requirements for formal training and explicit credentialing for new teachers. There are several recognized certification programs for meditation instructors. Widely accepted credentialing and licensure for meditation instructors, however, are currently lacking.

Transcendental meditation® (TM®): TM® is a controversial practice that involves the technique of focusing on a “mantra” (a sound, word, or phrase that is repeated to oneself over and over, either aloud as a chant, or silently). Maharishi Mahesh Yogi, who became well known due to famous followers such as the musical group The Beatles, introduced TM® to the West in the late 1950s. A goal of TM® is to reach a state of consciousness that is beyond wakefulness, sleep, or dreaming, in which relaxed awareness is achieved. When thoughts intrude, they may be noticed passively before returning to the mantra. Some practitioners suggest that when meditating individuals attain a state of “pure consciousness,” they can influence the emotions or mental states of people around them. This area has not been scientifically evaluated. Other claimed benefits of TM® are also controversial, such as improved IQ, reduced violent tendencies, and “yogic flying.” It has been argued as to whether TM® should be classified as a religion or not, and some groups have suggested that TM® constitutes a cult or religious sect. TM® is a registered trademark with centralized administration of training at program centers worldwide.

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
High blood pressure
In general, it appears that regular practice of meditation may promote relaxation and reduce blood pressure. More research is needed before conclusions can be made. However, meditation can be recommended, in addition to healthy diet and exercise, for the prevention (vs. treatment) of hypertension.
Quality of life (cancer)
There is good evidence that various types of meditation may help improve quality of life for cancer patients. Studies have shown benefits for mood, sleep quality, and the stresses of treatment. The specific effects of meditation are not fully understood. However, meditation can be recommended as a form of support for cancer patients.
The evidence indicates that meditation may help healthy people reduce the effects of stress. More studies are needed to further examine the dynamics of stress and meditation, but meditation can be recommended as a general health-promotion activity.
Meditation may help to improve cognitive function and blood pressure in the elderly, which may in turn promote overall health and longevity. More research is needed to identify the specific effects of meditation on aging. However, based on the available evidence, meditation may be considered as a health-promoting activity for the elderly.
Meditation may offer general stress-reducing effects for treating or preventing alcohol abuse. However, more studies are needed before conclusions can be made concerning use of meditation for alcoholism treatment or prevention.
Studies suggest that meditation may offer some benefits for anger management. However, more studies are needed to recommend meditation as a form of behavioral intervention for anger.
Various forms of meditation, including mindfulness, transcendental meditation®, and “meditation-based stress reduction programs” have been studied for their effects on anxiety. Better studies are needed before a conclusion can be made.
Studies suggest that Transcendental Meditation® may benefit asthma patients. Furthermore, Sahaja yoga, which incorporates meditation techniques, may have some benefit in the management of moderate to severe asthma. Further studies of meditation alone are needed before a firm conclusion can be drawn.
Meditation (in the form of Tai Chi or Qi gong) may help to improve balance in healthy elderly people. More research is needed to understand the specific effects of meditation on balance.
Cancer prevention
There is preliminary evidence that meditation may help improve the quality of life during cancer treatment. However, not enough research has shown meditation to help in the prevention of cancer. More studies are needed.
Cardiovascular disease
There is not enough evidence that meditation has any clinical effects in cardiovascular disease. More studies are needed to determine whether meditation may have benefits and whether specific techniques might be more effective than others.
Cardiovascular rehabilitation
Meditation may offer general benefits for mood and stress, which are likely to aid in cardiac care. However, more studies are needed to recommend meditation as a specific treatment during cardiac rehabilitation.
Chronic fatigue syndrome
Mindfulness meditation with Qi gong may contribute to improved overall health. However, not enough studies have examined the specific effects of meditation on chronic fatigue syndrome. More studies are needed before meditation can be recommended as a treatment.
Chronic pain
Meditation, yoga, and other stress management techniques may help to relieve chronic pain. However, since meditation is often used with many other treatments and therapies, the specific benefits of meditation are not clear. More studies are needed that examine the specific effects of meditation as a treatment for chronic pain.
Cognitive function
Some forms of meditation may have positive effects on cognitive function. However, there is not enough clear evidence that any specific form of meditation can support or enhance cognitive function.
Congestive heart failure
Meditation may improve quality of life in elderly patients, and may even potentially reduce the risk for congestive heart failure. However, there is not enough evidence to make firm conclusions about meditation in congestive heart failure, and more studies are needed.
Crohn’s disease
Meditation may improve Crohn’s disease symptoms. However, there is not enough evidence to come to a conclusion about meditation in Crohn’s disease, and more studies are needed.
Some forms of meditation may prevent relapse in patients who have had bouts of major depression. However, more studies are needed to confirm that meditation may be used as part of treatment for depression.
Eating disorders
Preliminary studies show that meditation may help treat binge eating in overweight individuals. More research is needed in this area.
Emotional distress
One randomized controlled trial has shown that meditation may reduce distress and improve positive mood states. More research is needed in this area.
Yoga meditation may help prevent seizures in epileptics, although higher quality studies are needed to come to a firm conclusion.
It has been suggested that mindfulness meditation may help improve symptoms in patients with fibromyalgia. Better quality research is necessary before a conclusion can be formed.
High cholesterol
Preliminary research suggests that meditation may help manage high cholesterol. More research is needed in this area.
Research suggests that meditation may help improve quality of life in patients with HIV/AIDS. Meditation may even affect immune function, though the studies have been inconclusive. More studies are needed to establish how meditation may be useful as an adjunctive therapy in HIV/AIDS patients.
Immune function
Research suggests that there may be increased antibody response after meditation. Further study is needed to confirm these findings.
Irritable bowel syndrome (IBS)
Some forms of meditation may help to ease the symptoms of IBS. However, more research is needed before firm conclusions can be made.
Some forms of meditation may help to ease migraine symptoms. However, more research is needed before firm conclusions can be made.
Mood enhancement
For healthy subjects, there is not enough scientific evidence that meditation can improve mood. More studies are needed to determine whether meditation has any specific effects on mood.
Multiple sclerosis
Research suggests an improvement in multiple sclerosis symptoms after meditation. Further study is needed to confirm these findings.
Organ transplantation
It is suggested that meditation may help to improve quality of life in organ transplant patients. However, more research is needed before firm conclusions can be made.
Post-traumatic stress disorder (PTSD)
There is some evidence that certain meditative techniques may improve symptoms in people with PTSD. However, more studies are needed to examine the specific benefits of meditation before it is recommended for use in patients with PTSD.
Some evidence suggests that meditation may help to reduce complications in pregnancy or childbirth. However, more studies are needed to recommend meditation for specific benefits during pregnancy.
Meditation has been suggested to improve healing of psoriasis, when used in combination with standard treatments. More studies are needed to investigate the specific effects of meditation on psoriasis.
Psychological conditions
When used in combination with standard psychiatric treatment, meditation may improve treatment outcomes in patients with various psychological conditions. However, more research is needed before meditation is recommended to use along with psychotherapy.
Quality of life
Meditation has been used for improvements in quality of life in a variety of patient populations. More research is needed in this area.
Sleep disorders
The ability of meditation to improve sleep has been suggested in patients being treated for drug abuse, as well as patients with breast cancer. However, there is currently not enough clinical evidence that meditation improves sleep in patients with breast cancer, drug abuse problems, or in healthy subjects.
Smoking cessation
Available evidence does not indicate whether meditation can help people to quit smoking. More studies are needed in this area.
Substance abuse
Meditation may not be as effective as other therapies for preventing relapse in recovering cocaine addicts. More studies are needed before a conclusion can be made about meditation as a treatment for cocaine dependence.

Numerous theories have been advanced around the mechanisms of action and potential benefits of meditation. It has been suggested that meditation reduces activity of the sympathetic nervous system, which is responsible for the “fight or flight” response, leading to a slower heart rate, lower blood pressure, slowed breathing, and muscle relaxation. Multiple studies of transcendental meditation® have noted decreased metabolism, heart rate, blood pressure, breathing, and oxygen consumption. Changes in blood flow to the brain and in brain wave patterns have been reported, as well as alterations in hormone levels. Decreased lactic acid levels have also been reported. Better quality studies are necessary around the mechanism of action of different forms of meditation before firm conclusions can be reached.


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.

Allergies, angina (chest pain), arrhythmia, attention deficit hyperactivity disorder (ADHD), blood vessel disorders, breast milk abnormalities, chronic diseases, coping skills, decrease in heart rate, diabetes, diarrhea, disease diagnosis or treatment (psychotherapy adjunct), dyslexia, emphysema, exercise performance (in patients with chest pain), gag reflex abnormalities, infertility, inflammatory bowel syndrome, low blood cortisol levels, menopausal symptoms, muscle tension, palliative care (end-of-life care), Parkinson’s disease, peripheral neuropathy (in HIV), peripheral vascular disease, post-polio pain, premenstrual syndrome, psychosis, Raynaud’s disease, reducing oxygen consumption, relaxation, schizophrenia, skin disorders, stroke prevention, suicide prevention, trauma, upset stomach.


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.

Most forms of meditation are regarded as being safe for healthy individuals. There are rare reports of adverse effects in people with underlying mental illnesses, including episodes of mania or depersonalization. Some publications warn that intensive meditation or retreats may lead to disorientation, anxiety, or depression. People with psychiatric disorders should consult with their primary mental healthcare professional(s) before starting a program of meditation, and should explore how meditation may or may not fit in with their current treatment plan.

An increased risk of seizure has been reported in a poorly described study, and therefore people at risk of seizures should speak with their primary healthcare professional before starting a meditation program.

The practice of meditation should not delay the time to diagnosis or treatment with more proven techniques or therapies and should not be used as the sole approach to illnesses.


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); Paul Ingraham, RMT (private practice); David Lee, PharmD (Massachusetts College of Pharmacy); Katie Nummy, BS (Northeastern University); Michael Rotblatt, MD (UCLA Medical Center); Nancy Russell, MD (MD Anderson Cancer Center, University of Texas); 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. Abgrall-Barbry G, Consoli SM. [Psychological approaches in hypertension management] Presse Med 2006 Jun;35(6 Pt 2):1088-94.
  2. Barnes VA, Treiber FA, Davis H. Impact of transcendental meditation on cardiovascular function at rest and during acute stress in adolescents with high normal blood pressure. J Psychosom Res 2001;51(4):597-605.
  3. Barnhofer T, Duggan D, Crane C, et al. Effects of meditation on frontal alpha-asymmetry in previously suicidal individuals. Neuroreport 2007 May 7;18(7):709-12.
  4. Brazier A, Mulkins A, Verhoef M. Evaluating a yogic breathing and meditation intervention for individuals living with HIV/AIDS. Am J Health Promot 2006 Jan-Feb;20(3):192-5.
  5. Carlson LE, Garland SN. Impact of mindfulness-based stress reduction (MBSR) on sleep, mood, stress and fatigue symptoms in cancer outpatients. Int J Behav Med 2005;12(4):278-85.
  6. Holloway E, Ram FS. Breathing exercises for asthma. The Cochrane Library 2002;(2).
  7. Kabat-Zinn J, Massion AO, Kristeller J, et al. Effectiveness of a meditation-based stress reduction program in the treatment of anxiety disorders. Am J Psychiatry 1992;149(7):936-943.
  8. Keefer L, Blanchard EB. A one year follow-up of relaxation response meditation as a treatment for irritable bowel syndrome. Behav Res Ther 2002;40(5):541-546.
  9. Krisanaprakornkit T, Krisanaprakornkit W, Piyavhatkul N, et al. Meditation therapy for anxiety disorders. Cochrane Database Syst Rev 2006 Jan 25;(1):CD004998.
  10. Lee SH, Ahn SC, Lee YJ, et al. Effectiveness of a meditation-based stress management program as an adjunct to pharmacotherapy in patients with anxiety disorder. J Psychosom Res 2007 Feb;62(2):189-95.
  11. Morone NE, Greco CM. Mind-body interventions for chronic pain in older adults: a structured review. Pain Med 2007 May-Jun;8(4):359-75.
  12. Oman D, Richards TA, Hedberg J, et al. Passage meditation improves caregiving self-efficacy among health professionals: a randomized trial and qualitative assessment. J Health Psychol. 2008 Nov;13(8):1119-35.
  13. Paul-Labrador M, Polk D, Dwyer JH, et al. Effects of a randomized controlled trial of transcendental meditation on components of the metabolic syndrome in subjects with coronary heart disease. Arch Intern Med 2006 Jun 12;166(11):1218-24.
  14. Schneider RH, Alexander CN, Rainforth M, et al. Randomized controlled trials of effects of the transcendental meditation program on cancer, cardiovascular, and all-cause mortality: a meta-analysis. Ann Behav Med 1999;21(Suppl):S012.
  15. Speca M, Carlson LE, Goodey E, et al. A randomized, wait-list controlled clinical trial: the effect of a mindfulness meditation-based stress reduction program on mood and symptoms of stress in cancer outpatients. Psychosom Med 2000;62(5):613-622.


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.