November Research Extracts: Studies on Coffee and Green Tea, Omega-3s, Almonds, and Exercise
Welcome to the November 2020 edition of Research Extracts. “The Extracts” is designed to keep busy practitioners and savvy consumers up to date on the latest research on diet, nutrients, botanicals, the microbiome, the environment, and lifestyle approaches to good health. Our medical team, which includes NDs, MDs, PhDs, RDs, an MS, and an LAc, has summarized the essence of several of the most interesting studies.
In this issue you will find studies on (1) coffee and green tea for blood sugar, depression, and microbiome support in type 2 diabetes, (2) almonds and a low carb diet in type 2 diabetes, (3) omega-3s for cognitive support in children and young adults, and (4) exercise timing and decreased prostate and breast cancer risk.
Coffee or Tea? Which is better for your health?
The debate over the health benefits of coffee and green tea, and which is better, has been discussed by health care practitioners and warm drink lovers for ages. Science has given some attention to this question and, for some populations, the answer seems to be there are benefits to both. One of these populations is individuals who are at risk for developing diabetes. More than 30 studies1 show multiple benefits for green tea in reducing risk factors for diabetes, including blood pressure, blood fats, and body weight/body mass index. An almost equal number of well executed studies (a 2016 review included 282) showed that coffee (both caffeinated and decaffeinated) contributes to a substantially lower risk of developing diabetes and improves insulin sensitivity.
So which is better? If you have risk factors for developing diabetes, then are you better off drinking coffee or green tea? How about both.
A new study from Japan suggests that both is the answer.3 In this study, which analyzed the habits of 5,000 individuals in a diabetes registry over a 5-year period, both green tea and coffee consumption were separately associated with an overall lower risk of dying (“all-cause mortality”). Specifically, drinking 1-4 cups of tea daily was associated with a 15-40 percent lower risk of dying during the study period, and drinking 1-2 cups (or more) of coffee daily was associated with a 12-41 percent lower risk of dying.
The lowest risk of mortality, however, was in the group of individuals who drank both coffee and green tea. The researchers found:4
- A 51-percent lower risk in those drinking 2-3 cups of green tea plus 2 or more cups of coffee daily
- A 58-percent lower risk in those drinking 4 or more cups of green tea plus 1 cup of coffee daily
- And a whopping 63-percent lower risk for those drinking a combination of 4 or more cups of green tea plus 2 or more cups of coffee daily
Although there are definitely some individuals who can’t drink coffee or green tea, this study indicated broad benefits for drinking both, perhaps especially for those with, or at risk of, diabetes.
Contributed by Jacqueline Jacques, ND
- Therapeutic potential of green tea on risk factors for type 2 diabetes in obese adults – a review – Ferreira – 2016 – Obesity Reviews – Wiley Online Library. https://onlinelibrary.wiley.com/doi/abs/10.1111/obr.12452 [Accessed October 22, 2020.]
- Ding M, Bhupathiraju S, Chen M, et al. Caffeinated and decaffeinated coffee consumption and risk of type 2 diabetes: a systematic review and a dose-response meta-analysis. Diabetes Care 2014;37(2):569-586. doi:10.2337/dc13-1203
- Komorita Y, Iwase M, Fujii H, et al. Additive effects of green tea and coffee on all-cause mortality in patients with type 2 diabetes mellitus: the Fukuoka Diabetes Registry. BMJ Open Diabetes Res Care 2020;8(1):e001252. doi:10.1136/bmjdrc-2020-001252
- Green tea, coffee, and mortality risk in T2DM. Published October 20, 2020. https://www.medpagetoday.com/endocrinology/diabetes/89223 [Accessed October 22, 2020.]
Almonds can improve mood, blood sugar, and gut microbiome in type 2 diabetes
Low carbohydrate diets have shown promise for improving glucose metabolism, particularly when the diet utilizes nuts, such as almonds, which have also been studied for their beneficial effects on the brain and in neuropsychiatric disorders. The role of dietary management in type 2 diabetes mellitus (T2DM) is well studied with a focus on managing blood sugar metabolism. However, comparatively little research has examined the relationship between diet and depression in individuals with T2DM.
In a recent study, patients with T2DM were divided into two treatments groups: an almond-based, low-carbohydrate diet or a low fat diet. Blood markers for glucose metabolism, height, weight, calculated body mass index (BMI), a fecal microbiome analysis, and screening for symptoms of depression were completed before and after three months of the recommended dietary intervention.
Positive effects of the almond-based, low carb diet included:
- Hemoglobin A1c, a marker of blood glucose over time, was significantly lower (p<0.01) than in the low fat diet group
- Both body weight and BMI were significantly reduced (p<0.05)
- Symptoms of depression were decreased compared to the low fat diet group (p<0.01)
- Gut microbiome diversity was improved, including an increase in the short-chain fatty acid-producing bacterial genera Roseburia (p<0.01), Ruminococcus (p<0.05), and Eubacterium (p<0.01)
The researchers concluded that an almond-based, low carbohydrate diet can be an effective treatment strategy for improving depression, glucose metabolism, and the gut microbiome of patients with T2DM. In addition, they theorized that changes in the gut microbiome could be at least partially responsible for improvements in mood and blood sugar metabolism.
Contributed by Jennifer Greer, ND, MEd
- Ren M, Zhang H, Qi J, et al. An almond-based low carbohydrate diet improves depression and glycometabolism in patients with type 2 diabetes through modulating gut microbiota and GLP-1: A randomized controlled trial. Nutrients 2020;12(10):E3036. Published 2020 Oct 3. doi:10.3390/nu12103036
Omega-3 blood levels, intake levels, and cognitive benefits in children and young adults
The Omega-3 Index (O3I) is a standardized measure representing the amount of DHA and EPA in red blood cells. It is a tool that can be used to assess the effectiveness of various sources of omega-3s for increasing levels in the body. Omega-3 long-chain polyunsaturated fatty acids (LCPUFA), such as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), play an important role in many neurological processes. Evidence in other areas of health, such as cardiovascular health, with DHA intake of greater than 500 mg per day or O3I levels of 8-11 percent have shown benefit. In addition, the known role of omega-3 LCPUFAs in the brain suggest they are associated with cognitive improvement, although studies in this area have conflicting or inconclusive findings. Many explanations have been offered, ranging from insufficient blood levels to insufficient intake, as well as inconsistent or poor quality of omega-3 sources.
A review of randomized, placebo-controlled trials assessing cognition in the context of omega-3 supplementation in healthy participants (ages 4-25 years) found a minimum of 6-percent O3I and 450 mg DHA and EPA supplementation was associated with improvements on cognitive tests in healthy children and young adults. These values are consistent with findings related to other aspects of health and to other reviews and meta-analyses. The authors suggest that previous inconclusive or negative studies failed to measure omega-3 blood levels, making it impossible to assess whether supplementation was sufficient in the study population.
The authors, along with the International Society for the Study of Fatty Acids, recommend that future studies measure omega-3 blood levels to provide more complete evidence on which to draw conclusions.
Explore Thorne's omega-3 products
Contributed by Sheena Smith, MS MA
- Van der Wurff I, Meyer B, de Groot R. Effect of omega-3 long chain polyunsaturated fatty acids (n-3 LCPUFA) supplementation on cognition in children and adolescents: a systematic literature review with a focus on n-3 LCPUFA blood values and dose of DHA and EPA. Nutrients 2020;12(10):3115. doi:10.3390/nu12103115
Morning exercise might decrease risk for breast and prostate cancer compared to other times of day
An increasing body of research-based knowledge is emerging on the health effects of exercise, as are studies on the effects of circadian rhythm disruptions on health and disease. Based on previous research showing that exercise can impact circadian rhythms, this study examined the effects of exercise, particularly timing of exercise, on breast and prostate cancer risks.
The study included 2,795 subjects: 781 women with breast cancer, 865 matched female controls, 504 men with prostate cancer, and 645 matched male controls. Information was gathered via in-person interviews. Exercise earlier in the morning (8-10 a.m.) was associated with decreased risk for breast and prostate cancer compared to no activity (odds ratio of 0.74 – which means earlier morning exercise decreased odds of breast or prostate cancer by 26 percent compared to not exercising at all). Meanwhile, there was no protective effect noted for late morning (10-noon) or afternoon exercise/activity. Evening (7-11 p.m.) exercise yielded some protection against prostate cancer, but not breast cancer. In addition, participants were divided by chronotype – morning, intermediate, or night – meaning they consider themselves more of a morning person, night person, or somewhere in between. The benefits of morning exercise for both breast and prostate cancers were more pronounced for intermediate and night chronotypes than for morning types.
This information adds to the growing body of information about circadian rhythms and health.
How is your melatonin-cortisol circadian rhythm?
Contributed by Kathi Head, ND
- Weitzer J, Castaño-Vinyals G, Aragonés N, et al. Effect of time of day of recreational and household physical activity on prostate and breast cancer risk (MCC-Spain study). Int J Cancer 2020 Sep 25. doi: 10.1002/ijc.33310. Epub ahead of print. PMID: 32976649.