Nuts

Here are some nut studies that link to benefits in connection with diabetes, heart disease, and inflammation. However, it should be noted that they are often very small, and usually funded by nut organizations. I wouldn't put too much weight on such.

Nuts linked to improved type 2 diabetes health

A 3-month study involving 117 older adults (mean age 62) with diabetes found that 75g of nuts (½ a cup) a day, as a replacement for carbohydrate foods, can improve glycemic control and blood lipids in those with type 2 diabetes.

The nuts used were a mixed lot of tree nuts (almonds, Brazils, cashews, hazelnuts, pecans, pine nuts, pistachios, macadamias and walnuts) and peanuts. improved blood lipid levels and blood sugar levels in individuals with non-insulin dependent diabetes.

https://www.eurekalert.org/pub_releases/2018-05/mp-itn052218.php

Jenkins, D.J.A., C.W.C. Kendall, B. Lamarche, M.S. Banach, K. Srichaikul, E. Vidgen, S. Mitchell, T. Parker, S. Nishi, B. Bashyam, R. de Souza, C. Ireland, S.C. Pichika, J. Beyene, J.L. Sievenpiper, R.G. Josse, 2018. Nuts as a replacement for carbohydrates in the diabetic diet: a reanalysis of a randomised controlled trial. Diabetologia https://doi.org/10.1007/s00125-018-4628-9

Eating pecans had significant effect on biomarkers of heart disease and type 2 diabetes

A very small 4-week study involving 26 overweight and obese adults (average age 59) found that those given a diet with pecans substituted for 15% of the total calories significantly improved insulin sensitivity and had a significant effect on markers of cardiometabolic disease.

Both the control diet and the pecan-rich diet were low in fruits, vegetables and fiber.

https://www.eurekalert.org/pub_releases/2018-03/kc-n-eph032218.php

The study entitled "A Pecan-Rich Diet Improves Cardiometabolic Risk Factors in Overweight and Obese Adults: A Randomized Controlled Trial" is available online and was presented at the American Society for Nutrition Annual Conference, Nutrition 2018 held in Boston in June.

A handful of nuts a day cuts the risk of a wide range of diseases

A review of 29 studies involving some 819,000 participants has concluded that people who eat at least 20g of nuts (a handful) a day have a 30% lower risk of heart disease, as well as lower risks of cancer, respiratory disease, and diabetes.

The study included all kinds of tree nuts, and also peanuts. The results were in general similar. There was little evidence of further improvement in health outcomes as a result of eating more than 20g of nuts.

Nuts and peanuts are high in fibre, magnesium, and polyunsaturated fats. Some nuts, particularly walnuts and pecan nuts are also high in antioxidants.

https://www.eurekalert.org/pub_releases/2016-12/icl-aho120216.php

Link between nut intake and inflammatory biomarkers

Data from 5,013 men and women participating in the Nurses' Health Study and Health Professionals Follow-up Study has revealed that higher nut intake (5 or more times per week) was associated with lower levels of inflammatory biomarkers (C-reactive protein (CRP) and Interleukin 6 (IL6)).

Research has also shown that nut consumption may be inversely related to body mass index (BMI), which is a strong determinant of inflammatory biomarkers, so it may be that the associations between nut intake and inflammatory markers are mediated in part through BMI.

http://www.eurekalert.org/pub_releases/2016-07/mp-itn072716.php

An updated systematic review of 25 years of research on the effect of walnut consumption on cardiovascular risk factors suggest that walnut-enriched diets may lead to significantly greater reductions in total cholesterol, LDL cholesterol, triglycerides, and apolipoprotein B, compared to control diets.

Walnut consumption had no adverse effects on body weight or blood pressure.

Most of the trials in this review had relatively small sample sizes, which could limit the ability to determine significant effects, and in some cases, the amount of walnuts consumed was relatively large and might be difficult to maintain in a real-world setting. However, researchers still saw significant benefits when lower amounts of walnuts were consumed (less than 28 grams per day), particularly with total and LDL cholesterol.

https://www.eurekalert.org/pub_releases/2018-07/es-sre071218.php

Guasch-Ferré M, Li J, Hu FB, et al. Effects of walnut consumption on blood lipids and other cardiovascular risk factors: an updated meta-analysis and systematic review of controlled trials [published online ahead of print June 21, 2018]. Am J Clin Nutr. doi: 10.1093/ajcn/nqy091

Banel HK, Hu FB. Effects of walnut consumption on blood lipids and other cardiovascular risk factors: a meta-analysis and systematic review. Am J Clin Nutr. 2009;90(1):56-63.

Initial findings from the Walnuts and Healthy Aging (WAHA) study indicate that daily walnut consumption positively impacts blood cholesterol levels without adverse effects on body weight among older adults.

The study involved 707 healthy older adults of whom some were told to add significant daily amounts of walnuts (~15% of caloric intake) to their usual diet. They were not given any advice on what they should be eating, apart from that.

After a year, a comparison of the two groups found that those eating the walnuts were not any heavier than those who hadn't included walnuts in their diet, but the walnut-diet resulted in significant reductions in LDL cholesterol. There was minimal effect on triglycerides and HDL cholesterol.

Another study reported at the conference found that daily consumption of 1.5 ounces of walnuts significantly affected the bacteria in the human gut in a way that was favorable to decreasing inflammation and cholesterol. This was a small study involving only 18 healthy adults. However, a 2015 study with rats similarly found that a diet with walnuts had a significant effect on gut bacteria communities.

Walnuts are unique among nuts in being primarily composed of polyunsaturated fat. This includes alpha-linolenic acid (ALA), the plant-based omega-3 fatty acid, which is known to reduce inflammation. Walnuts are the only nut that contain a significant amount of alpha-linolenic acid.

Walnuts are also said to be an excellent source of antioxidants — indeed, second only to blackberries.

http://www.eurekalert.org/pub_releases/2016-04/es-nri040116.php

Ros E, Rajaram S, Sala-Vila A, et al. Effect of a 1-Year Walnut Supplementation on Blood Lipids among Older Individuals: Findings from the Walnuts and Healthy Aging (WAHA) study [abstract]. FASEB J. 2016;30(Supp 1)293.4. Available at: http://www.fasebj.org/content/30/1_Supplement/293.4.abstract

Guetterman HM, Swanson KS, Novotny JA, et al. Walnut Consumption Influences the Human Gut Microbiome [abstract]. FASEB J. 2016;30(Supp 1)406.2. Available at: http://www.fasebj.org/content/30/1_Supplement/406.2.abstract

Vinson, JA & Cai, Y. (2012) Nuts, especially walnuts, have both antioxidant quantity and efficacy and exhibit significant potential health benefits. Food & Function, 3(2), 134-140 . http://pubs.rsc.org/en/Content/ArticleLanding/2012/FO/C2FO10152A#!divAbstract

A meta-analysis of 61 controlled trials has concluded that consuming tree nuts, such as walnuts, lowers total cholesterol, triglycerides, LDL cholesterol, and ApoB, the primary protein found in LDL cholesterol. Walnuts were investigated in 21 of the 61 trials, more than any other nut reviewed.

Consuming at least two servings (two ounces) per day of tree nuts had stronger effects on total cholesterol and LDL. The evidence also suggests that tree nut consumption may be particularly important for lowering the risk of heart disease in individuals with type 2 diabetes.

Walnuts have also been shown to reduce inflammation, and improve arterial function.

http://www.eurekalert.org/pub_releases/2015-11/es-sft111815.php

Del Gobbo, L., Falk, M.C., Feldman, R., Lewis, K., Mozaffarian, D. Effects of tree nuts on blood lipids, apolipoproteins, and blood pressure: systematic review, meta-analysis and dose-response of 61 controlled intervention trials. Am J Clin Nutr.2015; doi: 10.3945/ajcn.115.110965.

Kris-Etherton P. Walnuts decrease risk of cardiovascular disease: a summary of efficacy and biologic mechanisms. J Nutr. 2014; 10.39:2S-8S.

Zhao G, Etherton TD, Martin KR, et al. Dietary alpha-linolenic acid reduces inflammatory and lipid cardiovascular risk factors in hypercholesterolemic men and women. J Nutr 2004; 134: 2991-2997.

A small 12-week clinical trial involving 52 overweight, middle-aged adults with high total and LDL cholesterol has found that those who ate a daily snack of almonds significantly improved a number of cardiovascular risk factors compared to those who ate a banana muffin.

Specifically, they decreased total cholesterol, LDL-cholesterol non-HDL-cholesterol and remnant lipoproteins, and reduced abdominal fat mass, waist circumference and leg fat mass (not total weight or fat mass — this is about distribution).

The muffin and the 1.5 oz (42g) of whole natural almonds had the same number of calories. Otherwise, the participants ate the same balanced diet. Participants followed each diet for six weeks, with a two-week “washout” period in between. Adherence to the diets was 85%.

http://www.eurekalert.org/pub_releases/2015-01/pn-nrs010615.php

Berryman CE, West SG, Fleming JA, Bordi PL, Kris-Etherton PM. Effects of Daily Almond Consumption on Cardiometabolic Risk and Abdominal Adiposity in Healthy Adults with Elevated LDL-Cholesterol: A Randomized Controlled Trial. Journal of the American Heart Association 2015; 4:e000993 DOI: 10.1161/JAHA.114.000993.