Diet & Health

Further analysis of data from a 2011 study on the effect of the 'portfolio diet' on cholesterol has found that it also lowered blood pressure by an average 2% more than the DASH diet, a diet specifically designed to reduce hypertension, which is associated with a 5-10 mm blood pressure improvement.

The Canadian study involved 241 participants with hyperlipidemia, of whom 82 were randomly assigned to a DASH-type diet (control group) and 159 to the portfolio diet. Compared to the control, the portfolio diet reduced systolic, diastolic and mean arterial blood pressure by 2.1 mm Hg, 1.8 mm Hg and 1.9 mm Hg, respectively. Blood pressure reductions were small at 12 weeks and only reached significance at 24 weeks.

The portfolio diet includes foods that have been shown to lower cholesterol including mixed nuts, soy protein, plant sterols (found in vegetable oils and leafy vegetables) and viscous or soluble fiber. Viscous fiber is found only in plant-based food; rich sources include asparagus, Brussels sprouts, sweet potatoes, turnips, apricots, mangoes, oranges, legumes and oat bran.

However, the DASH diet did have higher compliance rates.

http://www.eurekalert.org/pub_releases/2015-11/smh-cd110515.php

Jenkins, D.J.A. et al. 2015. The effect of a dietary portfolio compared to a DASH-type diet on blood pressure. Nutrition, Metabolism and Cardiovascular Diseases, 25 (12), 1132-1139. http://dx.doi.org/10.1016/j.numecd.2015.08.006

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.

In a study involving 52 sedentary, overweight, middle-aged men and women (aged 45-65), both exercise and calorie restriction had positive — and equal — effects on insulin sensitivity, but a combination of both had twice as much benefit for glucoregulation as either single approach. All three programs were designed to achieve about the same amount of weight loss (6-8%).

The study also indicated that both exercise and calorie restriction improve regulation of glucose levels through weight loss, but also through mechanisms that are independent of weight loss.

What all this suggests is that, even if you're maintaining a healthy weight, how much you eat, and whether you exercise, are factors that have health implications.

http://www.eurekalert.org/pub_releases/2015-05/slu-ido050615.php

Weiss, E. P., Albert, S. G., Reeds, D. N., Kress, K. S., Ezekiel, U. R., McDaniel, J. L., … Villareal, D. T. (2015). Calorie Restriction and Matched Weight Loss From Exercise: Independent and Additive Effects on Glucoregulation and the Incretin System in Overweight Women and Men. Diabetes Care, 38(7), 1253–1262. http://doi.org/10.2337/dc14-2913

A British study involving 165 healthy nonsmoking adults (aged 40–70) has found that a diet based on UK health guidelines could reduce risk of a heart attack or a stroke by up to a third, compared to a traditional British diet

The predicted risk of cardiovascular disease over the next 10 years for the participants was estimated to be about 8% in the men and 4% in the women. Participants followed their diets for 12 weeks. Those on the modified diet ate oily fish once a week, more fruit and vegetables, replaced refined with wholegrain cereals, swapped high-fat dairy products and meats for low-fat alternatives, and restricted their intake of added sugar and salt. Participants were asked to replace cakes and cookies with fruit and nuts and were also supplied with cooking oils and spreads high in monounsaturated fat.

The average body weight in the group on the modified diet fell by 1.3 kg; that in the control group rose by 0.6 kg. Waist circumference was 1.7 cm lower in the dietary group compared to the control group. There were also significant falls in systolic blood pressure/diastolic blood pressure (4.2/2.5 mm Hg for daytime and 2.9/1.9 mm Hg for night time) and average heart rate. Cholesterol fell by 8%. High-sensitivity C-reactive protein (a marker for inflammation) was 36% lower. There was no significant change in markers for insulin sensitivity. Much of the fall in blood pressure could be accounted for by the drop in sodium.

http://www.eurekalert.org/pub_releases/2015-03/kcl-hdr031715.php

Reidlinger, D. P., Darzi, J., Hall, W. L., Seed, P. T., Chowienczyk, P. J., & Sanders, T. A. (2015). How effective are current dietary guidelines for cardiovascular disease prevention in healthy middle-aged and older men and women? A randomized controlled trial. The American Journal of Clinical Nutrition, 101(5), 922–930. http://doi.org/10.3945/ajcn.114.097352

A very small Israeli study, involving eight men and 10 women aged 30-70 with type 2 diabetes, has found that a big breakfast and a small dinner helped control blood sugar levels through the day.

Patients were randomly assigned to follow either a “B diet”, in which breakfast contained 2946 kilojoules, lunch 2523 kj, and dinner 858kj, or a “D diet”, which involved a 858 kj breakfast, 2523 kj lunch, and 2946 kj dinner. In other words, the same total amount of calories, in the same foods, was eaten by both groups, and lunch was the same for both, but the 'breakfast' and 'dinner' meals swapped timing.

After six days on the diet, patients ate their meals on the 7^th day at the lab, where glucose levels were repeatedly tested during the day. After a break of two weeks, each patient was put on the alternate diet, and the same procedure was followed.

It was found that blood glucose levels rose 23% less after the lunch preceded by a large breakfast.

http://www.eurekalert.org/pub_releases/2015-03/afot-abo031615.php

Jakubowicz, D., Wainstein, J., Ahrén, B., Bar-Dayan, Y., Landau, Z., Rabinovitz, H. R., & Froy, O. (2015). High-energy breakfast with low-energy dinner decreases overall daily hyperglycaemia in type 2 diabetic patients: a randomised clinical trial. Diabetologia, 58(5), 912–919. http://doi.org/10.1007/s00125-015-3524-9

Mouse and human immune cells have demonstrated that a compound produced by the body when dieting or fasting (β-hydroxybutyrate — BHB) directly inhibits a protein, NLRP3, which is part of a complex set of proteins that drive the inflammatory response in several disorders, including autoimmune diseases, type 2 diabetes, Alzheimer's disease, atherosclerosis, and autoinflammatory disorders.

BHB is produced in response to fasting, high-intensity exercise, caloric restriction, or consumption of the low-carbohydrate ketogenic diet.

The finding helps explain why calorie restriction reduces inflammation.

http://www.eurekalert.org/pub_releases/2015-02/yu-amo021315.php

Youm, Y.-H., Nguyen, K. Y., Grant, R. W., Goldberg, E. L., Bodogai, M., Kim, D., … Dixit, V. D. (2015). The ketone metabolite β-hydroxybutyrate blocks NLRP3 inflammasome-mediated inflammatory disease. Nature Medicine, 21(3), 263–269. http://doi.org/10.1038/nm.3804

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

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

Studies have found that low levels of magnesium increases the chance that you will develop type 2 diabetes, but a large study shows that this association is modified by genetic variations in magnesium-related ion channel genes. So, for example, among Hispanic American women with high magnesium intake, those with one particular variant had a 35% lower risk of developing type 2 diabetes.

The study involved 7,287 black women and 3,285 Hispanic women aged 50-79.

http://www.eurekalert.org/pub_releases/2015-01/bu-t2d010715.php

http://www.futurity.org/diabetes-magnesium-833412/

Chan, K. H. K., Chacko, S. A., Song, Y., Cho, M., Eaton, C. B., Wu, W.-C. H., & Liu, S. (2015). Genetic Variations in Magnesium-Related Ion Channels May Affect Diabetes Risk among African American and Hispanic American Women. The Journal of Nutrition, 145(3), 418–424. http://doi.org/10.3945/jn.114.203489

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.