Diet & Health

A trial in which 163 overweight adults with elevated blood pressure were given one of four complete diets that contained all their food for five weeks has found that a low glycemic diet did not improve insulin sensitivity, lipid levels or blood pressure. But it's important to note than all diets were based on a healthful DASH-type diet, varying only in their glycemic index and carbohydrate proportions.

So, the trial found that a healthy diet with low–glycemic index carbohydrate-containing foods didn't improve insulin sensitivity, HDL cholesterol levels, LDL cholesterol levels, or systolic blood pressure any more than the healthy diet with high–glycemic index foods It did reduce plasma triglyceride levels slightly more.

In fact, the low–glycemic index with high-carbohydrate diet was worse than the high–glycemic index, high-carbohydrate diet — decreasing insulin sensitivity and increasing LDL cholesterol and LDL apolipoprotein B levels. This finding was unexpected and inconsistent with other research. However, a meta-analysis of 28 trials found that lowering glycemic index did not affect HDL cholesterol or triglyceride levels and lowered LDL cholesterol level only if fiber content was also increased.

In line with the researchers' previous findings, the DASH diet had slightly better effects when its carbohydrate content was reduced. When the same calories were instead supplied by unsaturated fat and protein, triglycerides and VLDL levels were substantially lowered and diastolic blood pressure slightly lowered.

As in previous trials, all the DASH-type diets lowered blood pressure and LDL cholesterol levels.

Previous research has shown inconsistent results on whether low glycemic index helped people lose weight.

http://www.eurekalert.org/pub_releases/2014-12/bawh-lgd121614.php

Sacks FM, Carey VJ, Anderson CM, et al. Effects of High vs Low Glycemic Index of Dietary Carbohydrate on Cardiovascular Disease Risk Factors and Insulin Sensitivity: The OmniCarb Randomized Clinical Trial. JAMA. 2014;312(23):2531-2541. doi:10.1001/jama.2014.16658.

Goff  LM, Cowland  DE, Hooper  L, Frost  GS.  Low glycaemic index diets and blood lipids: a systematic review and meta-analysis of randomised controlled trials. Nutr Metab Cardiovasc Dis. 2013;23(1):1-10.

A review of studies investigating lifestyle interventions that can delay or prevent the onset of type 2 diabetes in people with prediabetes and focusing specifically on ones that looked at gender differences, found that both men and women benefited equally from the interventions. The review of 12 studies found that those who received lifestyle interventions (including diet and exercise) were 40% less likely to progress to type 2 diabetes after 1 year, and 37% less likely to progress after 3 years.

People involved in lifestyle interventions also experienced greater weight reductions, and greater reductions of fasting plasma glucose.

http://www.eurekalert.org/pub_releases/2014-11/d-bit112614.php

Glechner, A., Harreiter, J., Gartlehner, G., Rohleder, S., Kautzky, A., Tuomilehto, J., … Kautzky-Willer, A. (2014). Sex-specific differences in diabetes prevention: a systematic review and meta-analysis. Diabetologia, 58(2), 242–254. http://doi.org/10.1007/s00125-014-3439-x

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

Telomeres are the protective caps at the ends of chromosomes that affect how quickly cells age. With age, they shorten, and as their structural integrity weakens, the cells age and die quicker. Telomere length thus is a biomarker of cellular age. Stress is also thought to shorten telomere length.

A year-long study that looked at the effects of three healthy behaviors in 239 post-menopausal, non-smoking women has found that women who engaged in lower levels of healthy behaviors showed a significantly greater telomere shortening for every major life stressor that occurred. However, stress didn't lead to greater shortening in those women who maintained active lifestyles, healthy diets, and good quality sleep.

Shorter telomeres have become associated with a broad range of aging-related diseases, including stroke, vascular dementia, cardiovascular disease, obesity, osteoporosis diabetes, and many forms of cancer.

http://www.eurekalert.org/pub_releases/2014-07/uoc--hlm072414.php

Puterman, E., Lin, J., Krauss, J., Blackburn, E. H., & Epel, E. S. (2015). Determinants of telomere attrition over 1 year in healthy older women: stress and health behaviors matter. Molecular Psychiatry, 20(4), 529–535. http://doi.org/10.1038/mp.2014.70

Oregano and rosemary turn out to be packed with healthful compounds that may work in much the same way as prescription anti-diabetic medication in keeping their blood-sugar level in check. While greenhouse-grow herbs contained more polyphenols and flavonoids compared to the equivalent commercial dried herbs, commercial extracts of Greek oregano, Mexican oregano and rosemary were better inhibitors of the enzyme, required to reduce risk of type-2 diabetes.

http://www.eurekalert.org/pub_releases/2014-07/acs-rao072314.php

Bower, A. M., Real Hernandez, L. M., Berhow, M. A., & de Mejia, E. G. (2014). Bioactive Compounds from Culinary Herbs Inhibit a Molecular Target for Type 2 Diabetes Management, Dipeptidyl Peptidase IV. Journal of Agricultural and Food Chemistry, 62(26), 6147–6158. http://doi.org/10.1021/jf500639f

A Canadian study involving 141 people with Type 2 diabetes, who ate either a low glycemic index diet that included bread made with canola oil, or a whole wheat diet known to reduce the risk of cardiovascular disease, found that those on the canola bread diet experienced both a reduction in blood glucose levels and a significant reduction in LDL, or "bad," cholesterol. Moreover, the canola bread diet seemed to have the most significant impact on people who needed help the most — those whose HbA1c test measuring blood glucose over the previous two or three months was highest.

On the other hand, those on the whole wheat diet seemed to have better blood flow after 12 weeks than those on the canola bread diet.

http://www.eurekalert.org/pub_releases/2014-06/smh-rsb061314.php

Jenkins, D. J. A., Kendall, C. W. C., Vuksan, V., Faulkner, D., Augustin, L. S. A., Mitchell, S., … Leiter, L. A. (2014). Effect of Lowering the Glycemic Load With Canola Oil on Glycemic Control and Cardiovascular Risk Factors: A Randomized Controlled Trial. Diabetes Care, 37(7), 1806–1814. http://doi.org/10.2337/dc13-2990