Fruit vegetables

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 new class of lipids produced in human and mouse fat has been discovered, and these ones seem to be good for you. Following the discovery that diabetes-resistant mice had dramatically higher levels of these “fatty acid hydroxy fatty acids (FAHFAs)”, levels were found to be low in pre-diabetic humans. Moreover, when mice with the equivalent of type 2 diabetes were given this lipid, blood sugar levels dropped and insulin levels rose. FAHFAs also seem to reduce inflammation.

FAHFAS are found in low levels in a wide range of vegetables, fruits and other foods, as well as being (unlike omega-3 fatty acids) produced and broken down inside the body.

http://www.eurekalert.org/pub_releases/2014-10/si-sda100814.php

Yore, M. M., Syed, I., Moraes-Vieira, P. M., Zhang, T., Herman, M. A., Homan, E. A., … Kahn, B. B. (2014). Discovery of a Class of Endogenous Mammalian Lipids with Anti-Diabetic and Anti-inflammatory Effects. Cell, 159(2), 318–332. http://doi.org/10.1016/j.cell.2014.09.035

A small study involving 45 healthy, overweight or obese adults aged 21-70 has found that a diet including a daily Hass avocado was more effective than other cholesterol-reducing diets. Participants followed each of three diets for five weeks: one containing 24% fats and two containing 34% fats, one of which included an avocado and the other a comparable amount of high oleic acid oils (e.g. olive oil). There was a two-week break between each diet.

The avocado diet decreased bad cholesterol by 13.5 mg/dL, while LDL was decreased by 8.3 mg/dL on the moderate-fat diet and by 7.4 mg/dL on the low-fat diet.

http://www.eurekalert.org/pub_releases/2015-01/ps-aaa010715.php

Wang, L., Bordi, P. L., Fleming, J. A., Hill, A. M., & Kris Etherton, P. M. (2015). Effect of a Moderate Fat Diet With and Without Avocados on Lipoprotein Particle Number, Size and Subclasses in Overweight and Obese Adults: A Randomized, Controlled Trial. Journal of the American Heart Association, 4(1), e001355. http://doi.org/10.1161/JAHA.114.001355

A small study involving 48 post-menopausal women with pre- and stage 1 hypertension found that daily consumption of freeze-dried blueberry powder for eight weeks improved blood pressure and arterial stiffness. The amount of powder (22g) equated to one cup of fresh blueberries.

The improvement is thought to occur partly by helping nitric oxide-mediated vasodilation. Nitric oxide bioavailability is believed to increase endothelial-dependent vasodilation, leading to lower blood pressure.

After eight weeks those taking the blueberry powder showed a mean systolic blood pressure that was lower by 7 mmHg (5.1%) and mean diastolic blood pressure lower by 5 mmHg (6.3%), with no corresponding lowering in those taking a placebo. Nitric oxide measurements were significantly increased (68.5%) in the blueberry group. Arterial stiffness, measured by brachial ankle pulse wave velocity was significantly reduced (6.5%) after eight weeks in the blueberry-treated group, with, again, no changes in the control group. Aortic stiffness, measured by the carotid-femoral pulse wave velocity, did not change in either group, suggesting that peripheral arteries may be more responsive to dietary interventions than central arteries.

Among all fruits, blueberries are one of the richest sources of phenolic compounds. While previous studies have found positive effects on cardiovascular risk factors, they have all used large amounts of blueberry powder. These findings suggest that regular consumption of blueberries in quite moderate amounts could prevent or delay the progression of prehypertension to hypertension.

http://www.eurekalert.org/pub_releases/2015-01/ehs-dco010815.php

http://www.eurekalert.org/pub_releases/2015-01/fsu-bs010815.php

Johnson, S. A., Figueroa, A., Navaei, N., Wong, A., Kalfon, R., Ormsbee, L. T., … Arjmandi, B. H. (2015). Daily Blueberry Consumption Improves Blood Pressure and Arterial Stiffness in Postmenopausal Women with Pre- and Stage 1-Hypertension: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial. Journal of the Academy of Nutrition and Dietetics, 115(3), 369–377. http://doi.org/10.1016/j.jand.2014.11.001