Nutrients boost general and respiratory health
- Tea catechins
In this large review of studies covering 3,748 people, tea catechins were protective against flu and other upper respiratory infections. The findings include participants who consumed catechin-containing drinks or capsules over various study periods.
Overall, catechins in any form reduced flu and other upper respiratory tract infections by 32 percent compared to placebo. One study found gargling with tea catechins—not a common practice—reduced upper respiratory infection by 17 percent.
Doctors said this is the first comprehensive analysis to reveal the benefits of catechins while adhering to strict systematic review methods; two-tiered screening of publication titles and abstracts by independent researchers; evaluations of study quality and chances for bias, without limitation to the languages of the publications.
Reference: Clinical Nutrition; 2021, Vol. 45, P26 Reference: European Journal of Nutrition; 2021, Vol. 60, No. 8, 4189-4202
- Ashwagandha
Ancient Ayurvedic medical practice from India uses ashwagandha for its immune-boosting properties. Doctors believe they have identified the compounds in ashwagandha—called withanolide glycosides—responsible for its immune-boosting effects.
In the first, blinded phase of this study, 24 healthy men and women took a placebo or 60 mg of ashwagandha extract per day for 30 days. In a second open-label phase—where participants knew what they were taking—the groups switched placebo and ashwagandha.
After the first 30 days, levels of immune cytokines, and T-, B-, and NK cells increased. These are part of the general “innate” immune system, which attacks foreign cells. In addition, levels of immune antibodies that target specific invading antigens, part of the “adaptive” immune system, also increased. These include antibodies IgA, IgG, and IgM.
During the second 30-day phase, the new placebo group continued to show improved innate and adaptive immunity, as did those newly taking ashwagandha.
Discussing the findings, doctors said, “This is the first study to demonstrate ashwagandha withanolide glycosides possess potent immune stimulatory properties.”
Reference: Journal of Clinical Medicine; 2021, Vol. 10, No. 16, 3644
