Many natural products sold as dietary supplements are marketed for promoting health and well-being and preventing disease. However, there is often little to no evidence to support these claims. Here are five myths about popular natural products often used for disease prevention and wellness reasons and what the science really says about them for improving health.
Remember, take charge of your health—talk with your health care providers about any complementary health approaches you use. Together, you can make shared, well-informed decisions.
- Myth: Herbs such as valerian, chamomile, and kava are effective for insomnia.
Fact: Various herbs such as valerian, chamomile, and kava, and homeopathic medicines sometimes used as sleep aids have not been shown to be effective for insomnia, and important safety concerns have been raised about a few. For example, kava supplements have been linked to a risk of severe liver disease. However, there is evidence to suggest that using relaxation techniques, such as progressive relaxation, guided imagery, biofeedback, or deep breathing exercises, before bedtime can be helpful components of a successful strategy to improve sleep habits. Current evidence also suggests that melatonin may be useful in treating several sleep disorders, including jet lag, delayed sleep phase disorder, and sleep problems related to shift work.
- Myth: The herb passionflower can reduce stress and improve overall health.
Fact: There are very few studies of passionflower conducted in people and therefore insufficient evidence to determine whether passionflower is efficacious for any condition. However, there is some scientific evidence to date that suggests mindfulness meditation—a mind and body practice which cultivates abilities to maintain focused and clear attention, and develop increased awareness of the present—may help reduce symptoms of stress, including anxiety and depression. Results from a small body of research suggest that yoga may also affect stress and anxiety symptoms.
- Myth: A daily dose of a vitamin C supplement will prevent the onset of the common cold.
Fact: Several reviews have concluded that prophylactic vitamin C does not reduce the incidence of colds in the general population, but may be useful in reducing incidence of colds for people exposed to brief periods of severe physical exercise (e.g., marathon runners, skiers, and soldiers training in subarctic conditions).
- Myth: Taking garlic supplements will prevent heart disease.
Fact: There is no evidence that garlic supplements prevent heart disease. However, evidence from small studies is mixed about whether garlic supplements reliably lower cholesterol levels or change other known risk factors for cardiovascular disease.
- Myth:Turmeric (curcumin) and Ginkgo biloba supplements can prevent the onset of dementia and Alzheimer’s disease in people.
Fact: Although there is some evidence in laboratory studies that curcumin may affect brain function and the development of dementia, these results have not been demonstrated in clinical trials. In several large clinical trials, Ginkgo biloba has not been shown to effective in reducing either the overall incidence rate of dementia or Alzheimer’s disease incidence.