Thanks. In fact, I included a link to this study in my e-mail, although not your specific link: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5093315/ He is aware of this meta-study. Even so, he remains unconvinced, noting that statistical significance is not the same as practical significance. He said that the numbers they quoted for HDL elevation, etc., are too small to be of practical significance. I don't have a horse in this race. I was curious about the findings, wondering if I should start supplementing with ginger, and so I asked someone who is more qualified than I am to assess the study.
I'm into an Indian diet myself because the food tastes good but also it's known to keep the rate of cancer in India relatively low considering their pollution. Cinnamon, at least what is sold in cinnamon today is not that healthy, it's poisonous even in medium doses. I use it but not too much. Ginger is complicated, most of it comes from China and it's from polluted soil. Ginger in it's natural form is amazing but the "modern ginger" we get, not that awesome. Same goes for big fish, while good for vitamin D - you also get large doses of mercury.
https://www.healthline.com/nutrition/10-proven-benefits-of-cinnamon Yes much of Chinese soil is contaminated but certainly not all and not unlike many modern industrial countries. Yes, mercury is a problem. Krill oil is a better alternative for Omega 3.
I wonder what the results would be if the study was broken down by how much people excercised and body types. For example, caffeine appears to have negetive effects on sedentary people, causing them to crave food and an stimulative effect on active people. The people is Seattle have both high per capita coffee consumption and are one of the most overweight population groups in the country. Ginger and other herbs may have an greater benefit on active people.
If you live in Florida you will be able to grow both ginger and turmeric as perennials. Even in zone 8b where I live turmeric will grow as a perennial without winter protection. It dies down in winter after the first frost, but comes back in the spring. . I had it for years but am not growing it currently. A student from India gave me a start of turmeric. The ginger you buy in the grocery store grows easily but must be protected from freezing weather. By far the easiest, most effective and best way to stay healthy is to stay young. Don't age and your health problems are solved for life!
I sure it's good practice to have a healthful and varied diet that includes various herbs and spices and so on. But let's not get too carried away: https://www.self.com/story/health-benefits-of-turmeric-wildly-overstated https://www.skepticink.com/health/2013/12/09/cure-all-curry/ Curb your enthusiasm.