lower cortisol Archives - Amazing Health Advances

Forest Bathing to Boost Anticancer Immunity

The AHA! Team — Wed, 30 Jul 2025 06:38:14 +0000

Michael Greger M.D. FACLM via Nutrition Facts – Spending time in a forest, or even anticipating it, significantly lowers levels of cortisol (a stress hormone), more so than being in an urban area. Natural killer cells are one of the ways our body fights off cancer, and visiting a forest can induce a significant increase in both their numbers and their activity. I’ve previously shown how exposure to nature can have self-reported psychological benefits, but there was a dearth of data on changes in objective measurements, so I was excited to see this paper on the effects of forest bathing, “a traditional practice characterized by visiting a forest and breathing its air,” on levels of the stress hormone cortisol in the participants’ saliva. The level of cortisol in our saliva is considered an indicator of our stress level, and study participants’ salivary cortisol levels were significantly lower after walking in a forest or even just hanging out in one (“forest watching”), compared to walking or just being in a city, as you can see at 0:49 in my video Boosting Anticancer Immunity with Forest Bathing. However, the same effect was found before they went to the forest, too. Indeed, “forest bathing, in particular forest watching, was associated with significantly lower cortisol levels both before and after this practice if compared with visiting an urban area.” Therefore, it appears that just the thought of spending time in a forest relieves stress. So, “when comparing the effects of forest bathing versus urban visiting, the anticipated placebo effect…may play a more important role in influencing cortisol [stress] levels than the actual experience” of being in the forest. I was ready to dismiss this as just another nebulous psychological effect until I read this: “Studies on the effects of ‘Shinrin-yoku’ [forest bathing] on the immune function showed that visiting a forest can induce a significant increase in the number and activity of natural killer (NK) cells,” one of the ways our body fights off cancer. That got my attention. It all started with this study: Twelve men were taken on a long weekend trip to walk in the forest, and nearly all of them (11 out of 12) showed higher natural killer cell activity afterward. It wasn’t just a little increase either; they had about a 50 percent increase in NK cell activity after the trip compared to before they went to the forest, as you can see at 2:00 in my video. Now, exercise alone can affect immune function, but “there were no significant differences in walking steps before and during the trip.” The study participants were just walking in a forest instead. However, they were taken on a trip somewhere, which introduced other variables, so what about randomizing them to go on a city trip versus a forest trip? If there were some special forest effect, how long would it last? Do you have to walk in the forest every day? Before jumping into all that, let’s first see if it works in women, too. This study had the same kind of set-up, and the same kind of results: a significant boost in natural killer cell activity from walking in the woods. What’s more, this time, the participants were retested a week later, and their natural killer cell activity was still up. When they were retested a month after the trip their levels were back to baseline, as you can see at 2:45 in my video. So, walking in the woods once a week should do it, but the study involved a multi-day trip. Who can go to the forest all weekend, every weekend? How about just a day trip? The title gives it all away: “A Day Trip to a Forest Park Increases Human Natural Killer Activity and the Expression of Anti-Cancer Proteins in Male Subjects.” The same results and the same big jump measured the day after the trip compared to before and with the same staying power, as you can see at 3:08 in my video. And, natural killer cell activity was still boosted a week later. “This suggests that if people visit a suburban forest park once a week on a day trip, they may be able to maintain increased NK activity” and a boost in anticancer immune function. I’m still not convinced, though. How can you attribute the benefit to the forest itself, when all you have are before and after data? To make the case that nature had anything to do with it, you’d need a control group of study participants who took the same kind of trip but went somewhere else instead. And here we go. Again, the study title says it all: “Visiting a Forest, but Not a City, Increases Human Natural Killer Activity and Expression of Anti-Cancer Proteins.” By the end of the forest trip, the participants experienced a boost of 80 percent in NK activity after forest bathing, compared to only a 10 percent bump for the city walkers, as shown below and at 3:58 in my video. Both trips were matched for physical activity, alcohol, and sleep, too— other factors and behaviors that can affect immune function. So, we’ve got confirmation of boosted immunity, but only on the forest trip, “indicating that forest bathing does indeed enhance human NK activity.” Moreover, the researchers found that “the increased NK activity and numbers of NK cells induced by a forest bathing trip lasted more than 7 days, even 30 days, after the trip.” As you can see below and at 4:26 in my video, NK activity was still up a week later and even a bit up a month later. “This suggests that if people visit a forest once a month, they may be able to maintain increased NK activity. This may be important in health promotion and preventive medicine.” Now that we know that forest bathing induces a real effect, the next question is, Why? What is it about forests that give us the boost? (You can imagine Big Pharma wondering if it can be made into a pill.) We’ll find out next. The video I mentioned at the start is Are There Health Benefits of Spending Time in Nature?. Stay tuned for the follow-up post: Why Does Forest Bathing Boost Natural Killer Cell Function?. For other ways to improve immune function, check out related posts below. Key Takeaways Spending time in a forest, or even anticipating it, significantly lowers levels of cortisol (a stress hormone), more so than being in an urban area. Forest exposure is associated with a notable increase (around 50 percent) in NK cell activity, which plays a role in fighting off cancer. After a single forest trip, NK cell activity remains elevated for up to a week, and, in some cases, positive effects last up to a month. A day trip to the forest can be enough to maintain elevated NK cell activity if done weekly or monthly. Studies comparing forest versus city exposure confirm that forest environments uniquely boost immune function, independent of other factors like exercise and sleep. To read the original article click here.

The post Forest Bathing to Boost Anticancer Immunity appeared first on Amazing Health Advances.

Feeling Frazzled? Learn How Ashwagandha Supports Calm Mood and Clear Thinking

AHA Publisher — Tue, 18 Jan 2022 08:00:58 +0000

Lori Alton via NaturalHealth365 – For many, the past few years – marked by lockdowns, isolation, financial insecurity, and personal loss – have been challenging. So it’s not surprising that rates of anxiety and depression are ticking up nationwide. According to a report from the U.S. Centers for Disease Control and Prevention, the percentage of adults with anxiety or depressive disorder symptoms jumped from 36.4 percent to 41.5 percent in the period between August 2020 and February of 2021 alone. (In other words – if you’ve been feeling anxious, “down in the dumps,” or generally stressed out, you have plenty of company). Fortunately, a South Asian herb known as ashwagandha may offer natural relief. Ashwagandha, botanically known as Withania somnifera, is treasured in the Ayurvedic healing system as a “rasayana” – a substance believed to stimulate body functions, slow aging, promote health, and support longevity. Ashwagandha’s benefits also include calming and mood-lifting effects, making it a useful ally in these troubled times. Ashwagandha Benefits Include Improving the Body’s Ability to Cope With Prolonged Stress Chronic stress causes a litany of unhealthy consequences, including cognitive deficiencies, impaired regulation of blood sugar and blood fats, suppression of the immune system, and disturbed levels of DHEA (needed for healthy production of sex hormones). Stress also causes elevated cortisol levels (which is known as the “stress hormone”). Chronically elevated levels of cortisol can lead to unhealthy conditions such as high blood sugar and increased levels of abdominal fat. Ashwagandha is currently used in Ayurveda to reduce chronic stress, support the immune system, arrest premature aging and boost resistance to adverse environmental factors. Modern research has supported this ancient wisdom, and many scientists categorize ashwagandha as an adaptogen or a substance that helps the body deal with physical and emotional stress. (While “adaptogen” may lack the beauty of the word “rasayana,” the meaning is quite similar. By the way, other herbal adaptogens include Rhodiola Rosea, Panax ginseng, cordyceps, and astragalus). Let’s look at some of the ways in which ashwagandha earns its classification as a rasayana/adaptogen. Ashwagandha Is Investigated for Its Potential to Lower Cortisol and Promote Calm and Well-Being Studies show that ashwagandha may have the ability to lower cortisol levels. In one controlled, double-blind study of adults with chronic stress, participants were given either 125 mg or 250 mg of ashwagandha extract a day for 60 days. (A control group received a non-active placebo). The scientists found that the ashwagandha groups had greater reductions in cortisol levels when compared with the control group. In fact, some participants in the higher-dose group displayed decreases of up to 30 percent! Significantly, the ashwagandha groups also experienced improved well-being and substantial reductions in anxiety symptoms – along with physical benefits such as lower levels of inflammatory C-reactive protein, decreased pulse rate, and lower blood pressure. The scientists reported that the participants also experienced fewer manifestations of anxiety – such as fatigue, sleeplessness, sweating, headache, muscle pain, dry mouth, palpitations, and feelings of impending doom. And, in a separate study published in the Indian Journal of Psychological Medicine, researchers noted that participants who took 300 mg of ashwagandha extract a day reported a stunning 69 percent decrease in insomnia and anxiety. Incidentally, ashwagandha is a source of tryptophan, an amino acid that supports a stable mood and refreshing sleep. Ashwagandha Benefits May Include Improved Brain Function and Sharper Memory Ashwagandha contains a group of naturally-occurring steroids called withanolides. These antioxidant and anti-inflammatory compounds have been shown to protect against brain cell degeneration by reducing the production of harmful reactive oxygen species (free radicals). In animal studies, withanolides helped to reverse behavioral deficits, promote brain cell growth, and reduce amyloid plaque deposits in the brain. Human studies are limited, but several have supported ashwagandha’s ability to improve cognition and memory. For example, one controlled study showed that 500 mg of ashwagandha extract a day improved reaction time and task performance in healthy men – while another demonstrated that 600 mg a day significantly improved participants’ memory, task performance, and attention. Ashwagandha Helps with Blood Sugar Control In addition to contributing to deposits of unhealthy abdominal fat, elevated cortisol levels can cause high blood sugar. Ashwagandha, which is rich in blood sugar-lowering phenolic compounds and flavonoids, may help to address this problem. Maintaining stable blood sugar helps to discourage binge eating and food cravings, thereby helping to ward off overeating. Good blood sugar control may also help reduce disturbing mood swings. Preliminary test-tube and animal studies support ashwagandha’s blood sugar-lowering effects. Some clinical trials suggest that ashwagandha can reduce blood sugar levels and improve insulin sensitivity in levels in humans. If you would like to try supplementing with ashwagandha, experts recommend choosing a high-quality formulation standardized to contain 1 to 10 percent withanolides. Natural healers typically advise servings of 300 mg to 1,500 mg a day – but consult your qualified integrative physician before trying ashwagandha. (Of course, if your worry and distress are difficult to control, or if your symptoms are interfering with your daily life, discuss the situation with your trusted health professional). Ashwagandha seems to have both calming and energizing effects, with aficionados reporting that it can improve sleep quality, promote feelings of contentment, and help mental focus. So maybe it’s time to give this soothing herb a try! Sources for this article include: Healthline.com NIH.gov CDC.gov AdventHealth.com AdventHealth.com To read the original article click here.

The post Feeling Frazzled? Learn How Ashwagandha Supports Calm Mood and Clear Thinking appeared first on Amazing Health Advances.