Diet & Health

Data from 3,349 participants in the PREDIMED Study who were free of diabetes at baseline but at high cardiovascular risk, has found that those who consumed higher amounts of saturated fatty acids and animal fat had a twofold higher risk of developing type 2 diabetes over 4.5 years than those with a lower intake of saturated and animal fat. 266 participants developed diabetes during the period.

They also found that those who had a higher intake of legumes (lentils, chickpeas, beans and peas) had a 35% lower risk of developing type 2 diabetes compared to those eating the least amount. The main benefit came from lentils, with chickpeas running second. Those with a higher intake consumed at least 28.75 grams/day (equivalent to 3.35 servings/week).

There was also a positive benefit when half a serving per day of foods rich in protein or carbohydrates (such as eggs, bread, rice and baked potato) was replaced with a similar amount of legumes.

Legumes are rich in B vitamins, with beneficial minerals such as calcium, potassium and magnesium. They have long been thought to protect against type 2 diabetes.

https://www.eurekalert.org/pub_releases/2017-02/uriv-csa021617.php

https://www.eurekalert.org/pub_releases/2017-03/uriv-tco033017.php

Guasch-Ferré, M. et al. 2017. Total and subtypes of dietary fat intake and risk of type 2 diabetes mellitus in the Prevención con Dieta Mediterránea (PREDIMED) study. Total and subtypes of dietary fat intake and risk of type 2 diabetes mellitus in the Prevención con Dieta Mediterránea (PREDIMED) study Am J Clin Nutr 2017 105: 3 723-735; First published online February 15, 2017. doi:10.3945/ajcn.116.142034

Becerra-Tomás N, Díaz-López A, Rosique-Esteban N, Ros E, Buil-Cosiales P, Corella D, Estruch R, Fitó M, Serra-Majem Ll, Arós F, Lamuela-Raventós R.M, Fiol M, Santos-Lozano J.M, Diez-Espino J, Portoles O, Salas-Salvadó J, PREDIMED study investigators. "Legume consumption is inversely associated with type 2 diabetes incidence in adults: a prospective assessment from the PREDIMED study". Clinical Nutrition (2017). http://dx.doi.org/10.1016/j.clnu.2017.03.015.

• Long-known to lower LDL cholesteral, a new study shows oats also impact other markers that may be better measures of cardiovascular risk for those with diabetes or metabolic syndrome.
• An experimental study shows that whole grain foods significantly lower blood pressure compared to eating the equivalent refined grain foods.
• A review of population studies shows that the more whole grains you eat, the lower your risk of cardiovascular disease.

Eating oats lowers cholesterol on 3 markers

It’s long been known that eating oats can lower cholesterol levels, but the research focus has been on the effect on LDL cholesterol. However, there is growing evidence that two other markers provide an even more accurate assessment of cardiovascular risk:

• non-HDL cholesterol (total cholesterol minus HDL cholesterol)
• apolipoprotein B (apoB) — a lipoprotein that carries LDL cholesterol through the blood.

This is especially true for people with metabolic syndrome and Type 2 diabetes, since they typically don't have elevated LDL cholesterol levels.

In light of this, it’s good to see a review and meta-analysis of 58 clinical trials has concluded that eating oat fibre can reduce all three markers.

The reason is thought to lie in beta-glucan, a viscous soluble fibre, for which oats are a rich source. Oat bran contains twice as much as oat meal.

The review found that overall, LDL cholesterol was reduced by 4.2%, non-HDL cholesterol by 4.8% and apoB by 2.3%.

https://www.eurekalert.org/pub_releases/2016-10/smh-rse100616.php

Whole grain diet reduces cardiovascular disease risk

A study involving 33 overweight and obese adults who followed a whole grain diet for eight weeks and a refined grain diet during another eight week period, found that those on the whole grain diet saw a more than three-fold improvement in diastolic blood pressure compared to the refined grain diet.

This improvement equates to reducing the risk of death from heart disease by almost one-third, and the risk of death from a stroke by two-fifths.

Participants were under 50. Before age 50, an elevated diastolic blood pressure is associated with increased cardiovascular disease risk (diastolic is the bottom number, when you’re given a blood pressure reading).

Overall, there were substantial reductions in body weight, fat loss, systolic blood pressure, total cholesterol, and LDL cholesterol during both diet periods, but these differences were due to the people changing their normal dietary habits to carefully controlled diets. The order of diets was randomized, and there was a ten week period between them. The 33 participants included 6 men and 27 women.

The finding is supported by a meta-analysis of 45 different population studies that investigated whole grain intake in relation to risk of future illness or death due to specific causes. The review found that eating three more portions of whole grain foods a day was associated with a lower risk for all cardiovascular diseases and for dying of cancer, diabetes, and respiratory and infectious diseases. Three servings would be, say, two slices of whole-grain bread and one bowl of whole-grain cereal.

The benefits were dose-dependent, with the lowest risk found among those with the highest intake of whole-grain products: 7 to 7 ½ servings of whole grain products a day. This corresponds to 210-225 grams of whole grain products in fresh weight and about 70-75 grams of whole grains in dry weight.

https://www.eurekalert.org/pub_releases/2016-10/cc-ccs101816.php

http://www.eurekalert.org/pub_releases/2016-06/nuos-sso061516.php

Ho, H., Sievenpiper, J., Zurbau, A., Blanco Mejia, S., Jovanovski, E., Au-Yeung, F., . . . Vuksan, V. (2016). The effect of oat β-glucan on LDL-cholesterol, non-HDL-cholesterol and apoB for CVD risk reduction: A systematic review and meta-analysis of randomised-controlled trials. British Journal of Nutrition, 116(8), 1369-1382. doi:10.1017/S000711451600341X

Kirwan, J. P., Malin, S. K., Scelsi, A. R., Kullman, E. L., Navaneethan, S. D., Pagadala, M. R., … Ross, A. B. (2016). A Whole-Grain Diet Reduces Cardiovascular Risk Factors in Overweight and Obese Adults: A Randomized Controlled Trial. The Journal of Nutrition, 146(11), 2244–2251. https://doi.org/10.3945/jn.116.230508

Aune Dagfinn, Keum NaNa, Giovannucci Edward, Fadnes Lars T, Boffetta Paolo, Greenwood Darren C et al. Whole grain consumption and risk of cardiovascular disease, cancer, and all cause and cause specific mortality: systematic review and dose-response meta-analysis of prospective studies BMJ 2016; 353 :i2716 http://www.bmj.com/content/353/bmj.i2716

A small, Israeli study involving 48 overweight and obese older adults with Type 2 diabetes (average age 59) has found that those who ate a large breakfast containing whey protein managed their diabetes better.

Participants in the study were randomly alloted to one of three diets that contained the same number of calories, and followed the pattern: large breakfast, medium-sized lunch and small dinner. They followed this diet for 23 months. The groups varied in the type of breakfast: primarily whey protein; other proteins such as eggs, soy and tuna; a meal high in carbohydrates or starch.

After 12 weeks, the group on whey protein lost the most weight: 7.6 kg (16.7 pounds), compared to 6.1 kg (13.4 pounds) for those on the other proteins, and 3.1 kg (6.8 pounds) for those in the carbohydrate group. Those on whey protein were also more satiated and less hungry throughout the day, with lower glucose spikes after meals compared to the other two diets, and their HbA1C also decreased more than with the other two diets.

http://www.eurekalert.org/pub_releases/2016-04/tes-lwp040116.php

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

For two years, 70 obese postmenopausal women with normal fasting plasma glucose levels ate either a Paleolithic-type diet or a “prudent” diet. The Paleolithic-type diet was based on lean meat, fish, eggs, vegetables, fruits, nuts and berries, with rapeseed, olive oils and avocado as additional fat sources. The diet excluded dairy products, cereals, added salt and refined fats and sugar. 30% of the calories were supposed to come from protein, 30% from carbohydrates, and 40% from fats with high unsaturated fatty acid content. The prudent control diet had a markedly different target: 15% in protein, 30% in fat, and 55% in carbohydrates.

Both groups took part in 12 group sessions led by a dietitian, and kept ongoing records of their food intake.

Both groups lost significant body weight and had significantly less abdominal obesity, but the women eating the Paleolithic-type diet also had significantly lower levels of specific fatty acids associated with insulin resistance, compared with those on the prudent control diet. Presumably this reflects the marked change in the types of fats eaten. At the end of the two years, the women eating the Paleolithic-type diet reported that their intake of saturated fatty acids decreased by 19%, while monounsaturated fatty acids increased by 47% and polyunsaturated fatty acids by 71%.

http://www.eurekalert.org/pub_releases/2016-04/tes-apd040116.php

A pilot study involving 14 overweight or obese adults (average age 56) on a calorie-restricted diet, found that those whose diet had higher levels of protein showed greater improvements in their sleep score, regardless of the source of the protein.

In a follow-up study, 44 overweight or obese participants followed a normal-protein or a higher-protein weight loss diet (either 0.8 or 1.5 kg of protein for each kg of body weight) for 16 weeks. Sleep quality improved for those on the high-protein diet, but not for those on the normal-protein diet.

Sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI) questionnaire.

The sources of protein were beef and pork, or soy and legume.

Higher protein intake has also been linked to promoting body fat loss, retention of lean body mass and improvements in blood pressure.

http://www.eurekalert.org/pub_releases/2016-03/pu-lww032416.php

Zhou, J., Kim, J. E., Armstrong, C. L., Chen, N., & Campbell, W. W. (2016). Higher-protein diets improve indexes of sleep in energy-restricted overweight and obese adults: results from 2 randomized controlled trials. The American Journal of Clinical Nutrition, 103(3), 766–774. http://doi.org/10.3945/ajcn.115.124669

A new meta-analysis supports the link between intake of EPA and DHA omega-3 fatty acids, and reduction in major depressive disorder (MDD).

The meta-analysis only included studies in adult patients with MDD assessed using standardized clinical interviews, and excluded studies that specifically studied perinatal/perimenopausal or comorbid MDD, in order to get a more homogenous population. Studies not applying a randomized placebo-controlled trial design were also excluded. This criteria resulted in 13 studies with a total of 1233 participants (out of an original pool of 1955 studies).

The analysis of these studies showed a benefit for these omega-3 acids that was comparable to effects reported in meta-analyses of antidepressants. The effect was greater in studies supplementing higher doses of EPA and performed in patients already on antidepressants.

http://www.eurekalert.org/pub_releases/2016-03/g-nss031716.php

Mocking, R. J. T., Harmsen, I., Assies, J., Koeter, M. W. J., Ruhe, H. G., & Schene, A. H. (2016). Meta-analysis and meta-regression of omega-3 polyunsaturated fatty acid supplementation for major depressive disorder. Transl Psychiatry, 6, e756. Retrieved from http://dx.doi.org/10.1038/tp.2016.29

A Finnish study involving 2,189 healthy men aged 42-60 found that over 19 years, 417 men (19%) were diagnosed with type 2 diabetes. Those with high omega-6 polyunsaturated fatty acid concentrations in their blood were 46% less likely to develop diabetes. When analyzed, it turned out that this association depended on linoleic and arachidonic acid concentrations only; high serum gamma-linolenic and dihomo-γ-linolenic acid concentrations were linked to a higher risk.

The serum linoleic acid concentration is determined by the person's diet, and the main sources of linoleic acid are vegetable oils, nuts and seeds. Arachidonic acid is present in meat and eggs; however, the human body can also make arachidonic acid from linoleic acid.

Gamma-linolenic acid and dihomo-γ-linolenic acid are mainly formed in the human body from linoleic acid, but their concentrations in serum are very low.

Linoleic acid is the most common omega-6 fatty acid, and has been linked to a reduced risk of cardiovascular diseases as well as type 2 diabetes.

http://www.eurekalert.org/pub_releases/2016-03/uoef-hso032416.php

Teymoor Yary, Sari Voutilainen, Tomi-Pekka Tuomainen, Anu Ruusunen, Tarja Nurmi, Jyrki K Virtanen 2016. Serum n-6 polyunsaturated fatty acids, delta-5- and delta-6-desaturase activities and risk of incident type 2 diabetes in men: The Kuopio Ischaemic Heart Disease Risk Factor Study. American Journal of Clinical Nutrition, Published online March 24, 2016 http://ajcn.nutrition.org/content/early/2016/03/23/ajcn.115.128629.abstract

A review of recent neutral studies questioning the benefits of omega-3s for heart health suggests that the findings may have been due to a number of design issues, rather than a lack of substantiated clinical benefits in cardiovascular disease. The issues include such things as:

• aggressive cardiovascular drug treatment overshadowing the benefits of long-chain omega-3s
• high background long-chain omega-3 intake at study initiation
• too few subjects in the study
• treatment duration too short
• insufficient LC omega-3 dosage
• increase in omega-6 fatty acid intake during the study
• failure to assess the LC omega-3 status of the subjects prior to and during treatment
• lack of clarity concerning which mechanisms were expected to produce benefits

The existing body of gold-standard research showing omega-3s may reduce cardiovascular death risk, maintain healthy blood pressure and improve triglyceride levels also makes it difficult to conclude that EPA and DHA consumption does not contribute to a healthy heart.

http://www.eurekalert.org/pub_releases/2016-02/g-phb012916.php

Rice, H. B., Bernasconi, A., Maki, K. C., Harris, W. S., von Schacky, C., & Calder, P. C. (2016). Conducting omega-3 clinical trials with cardiovascular outcomes: Proceedings of a workshop held at ISSFAL 2014. Prostaglandins, Leukotrienes and Essential Fatty Acids (PLEFA), 107, 30–42. http://doi.org/10.1016/j.plefa.2016.01.003

Lower salt generally lowers blood pressure, but it turns out this may not apply in all instances. A mouse study suggests that a low-salt diet can increase the risk of hypertension if you have a disrupted circadian rhythm. Sleep disorders, shift work, disease, and aging are all potential signs of or triggers for circadian dysfunction.

A 24-hour blood pressure check may reveal that blood pressure is not falling, as it should, during the night. Nondipping blood pressure is estimated as high as 53% in patients being treated for hypertension. It may be that, for those with a disrupted circadian rhythm, the timing of antihypertensive medication should be different.

http://www.eurekalert.org/pub_releases/2016-02/mcog-wab020116.php

Pati, P., Fulton, D. J. R., Bagi, Z., Chen, F., Wang, Y., Kitchens, J., … Rudic, R. D. (2016). Low-Salt Diet and Circadian Dysfunction Synergize to Induce Angiotensin II–Dependent Hypertension in Mice. Hypertension, 67(3), 661–668. http://doi.org/10.1161/HYPERTENSIONAHA.115.06194