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Butter isn’t “back,” according to the American Heart Association

In order to clear up confusion about how different dietary fats relate to heart health, the American Heart Association published a Presidential Advisory on Dietary Fats and Cardiovascular Disease. In this paper, the researchers reviewed randomized controlled trials (the gold standard of nutrition research) as well as prospective observational studies (following large groups of people over long periods of time and noting their health outcomes). After reviewing all of the evidence, they concluded that replacing saturated fat (the types of fats found in red meat, butter, and milk) with polyunsaturated fat (found in fish, nuts, and seeds) can lower the risk of heart disease by 30%, which is on par with what cholesterol lowering medications can achieve. Similarly, they found that eating more monounsaturated fat (found in avocados, olive oil, and canola oil), more polyunsaturated fat, and less saturated fat is linked with lower rates of heart disease. Saturated fat is also linked with higher rates of “bad cholesterol” (LDL), which is thought to build up in artery walls and pose a risk for heart disease. These findings are in line with healthy dietary patterns around the world, including the Mediterranean diet.
Circulation. 2017 Jun 15. [Epub ahead of print.] (Sacks FM et al.)

Plant-Based Diet Can Reduce Obesity Risk by 43%

Nearly every healthy diet around the world is centered on a foundation of colorful produce. To see how eating more plant foods relates to obesity risk, scientists analyzed the diets of 16,000 healthy (non-obese) adults in Spain. Those eating the most plant-based diets (high in fruits, vegetables, grains, nuts, olive oil, and pulses, and low in meat, dairy, seafood, and other animal products) had a 43% lower risk  of becoming obese throughout the 10-year study than those with the most animal-based diets, even after controlling for age, physical activity, and other demographic factors. (Note that findings presented at meetings are typically viewed as preliminary until they’ve been published in a peer-reviewed journal.)
Presented at the European Congress on Obesity. Porto, Portugal. May 18, 2017. (Sanz J et al.)

Mediterranean-Based Diets Associated with Better Cognitive Function

Dementia is a serious neurological disease, so preventive measures are an important area of research.  In a study of 5,907 adults, researchers analyzed whether the Mediterranean diet and/or the MIND diet  (a diet similar to the Mediterranean diet, full of “brain-healthy” foods like leafy greens, nuts, berries, beans, whole grains, seafood, poultry, olive oil, and wine) have an effect on cognitive performance. Researchers found that those most closely following the Mediterranean Diet had 35% lower odds of having poor cognitive performance (assessed through tests of memory and attention), when compared to those not following a Mediterranean Diet. Results were similar for the MIND diet, probably because there is so much overlap in these two eating patterns.
Journal of the American Geriatrics Society. 25 April 2017. [Epub ahead of print.]  (McEvoy CT, et al.)

Mediterranean Diet Linked with Smaller Waists, Lower Inflammation, Lower Risk of Insulin Resistance in a Non-Mediterranean Population

Even if you don’t live in the Mediterranean, you can still follow a Mediterranean diet pattern emphasizing healthy foods like fish, whole grains, legumes, and olive oil. In a study of 1,194 Puerto Rican adults in the U.S., researchers analyzed their diets using several different health scores and also collected health measurements from the participants to look for relationships between diet and cardiometabolic health. Those whose diets most closely aligned with a Mediterranean diet were significantly more likely to have smaller waist sizes, a lower BMI, lower levels of inflammation (as measured by C-reactive protein), and lower levels of insulin resistance. The DASH Diet score and Healthy Eating Index 2005 score were not significantly associated with any health measurement, while the Alternative Healthy Eating Index was only weakly associated with some positive health markers.
The Journal of Nutrition. 2017 Apr;147(4):661-669. doi: 10.3945/jn.116.245431. Epub 2017 Mar 8. (Mattei J et al.)

Olive Oil Linked with Prevention & Management of Type 2 Diabetes

Olive oil is a staple of the Mediterranean diet, an eating pattern praised for its links to good health and wellbeing. To see how olive oil relates to type 2 diabetes, researchers in Europe analyzed data from 4 cohort studies (following people over time and monitoring their health) and 29 clinical trials (randomly assigning people to diets with or without olive oil). They found that those consuming the most olive oil had a 16% lower risk of developing type 2 diabetes than those consuming the least olive oil, with every 2 teaspoon increase in olive oil daily linked with a 9% lower risk. For patients who already had type 2 diabetes, adding olive oil to their diet significantly lowered their HbA1c, an indicator of better blood sugar control.
Nutrition & Diabetes. 2017 Apr 10;7(4):e262. (Schwingshackl L et al.)

Whole Plant Foods, Not Fads, Best for Heart Health

Magazines and news articles often jump from one “superfood” or fad diet to the next, but not all nutrition advice is backed up by substantial evidence. In this review, researchers analyzed the scientific support for various trending “heart healthy” foods and diets. Eating berries, nuts, extra virgin olive oil, leafy green vegetables, and plant-based diets are all strongly linked with better heart-health based on numerous studies. On the other hand, coconut oil, palm oil, eggs, juicing, and southern diets are linked with potential harm. Additionally, the researchers found no support that gluten-free diets are beneficial for people without gluten related disorders. The authors conclude that “Evidence-based healthy dietary patterns are high in fruits, vegetables, whole grains, legumes, and nuts in moderation, although some may include limited quantities of lean meats (including poultry and seafood), low-fat dairy products, and liquid vegetable oils.”
Journal of the American College of Cardiology. 2017 March 7;69(9):1172-87.

Mediterranean Diet Improves Function of Good Cholesterol

HDL is often referred to as good cholesterol, because it helps take “bad” (LDL) cholesterol from the bloodstream back to the liver for removal, protects blood vessels, and acts as an antioxidant. We used to only be able to measure the amount of HDL, but now, scientists are able to measure how well the HDL is functioning as well. To see how a Mediterranean diet affects HDL function, researchers analyzed data from 296 participants in the PREDIMED trial (a randomized, controlled study where people at risk of heart disease were assigned to either a Mediterranean diet with nuts, a Mediterranean diet with olive oil, or a low fat diet). Both Mediterranean diet groups improved cholesterol efflux capacity (how well the LDL is transported out by the HDL). However, the olive oil group also had improved HDL antioxidant properties, and improved blood vessel protection.
Circulation. 2017 Feb 14;135(7):633-643. (Hernaez A et al.) 

Mediterranean Diet May Help Improve Depression

To see how food might play a role in treating depression, Australian scientists randomly assigned 56 adults with moderate to severe depression to either 7 hours of dietitian-led counseling about a modified Mediterranean diet, or 7 hours of social support (keeping participants company, without using psychotherapy strategies) over the course of 12 weeks. The adults in the nutrition counseling group improved their diets by eating significantly more servings of whole grains, fruit, dairy, olive oil, pulses, and fish. After 12 weeks, 32% of the nutrition group and 8% of the social support group improved their depressive symptoms enough to achieve remission, and the nutrition group also scored significantly better on various markers of depression.
BMC Medicine. 2017 January 30;15:23. ( Jacka FN et al.)

Mediterranean Diet Shows Better Antioxidant Effect

The Mediterranean diet is a gold standard of healthy eating, and now scientists are learning more about the reasons behind its health benefits. Researchers randomly selected 75 adults (ages 55 to 80) with metabolic syndrome from one of three groups from the PREDIMED trial: a low-fat control diet, a Mediterranean diet with olive oil, or a Mediterranean diet with nuts. All participants had either type 2 diabetes or three or more risk factors for heart disease (smoking, high blood pressure, overweight or obesity, or family history of heart disease). Blood sample analysis revealed that both Mediterranean diet groups had better plasma antioxidant defenses and decreased xanthine oxidase activity (an enzyme linked with oxidative stress and health problems), but no difference in oxidative damage was found between the three groups. The researchers conclude that this antioxidant effect “could at least partially account for the previously reported beneficial effects of [the Mediterranean diet].”
Molecular Nutrition & Food Research. 2016 Dec;60(12):2654-2664. (A Sureda et al.)

Mediterranean Diet and Lifestyle Linked with Less Depression

A Mediterranean lifestyle encompasses much more than just red wine and olive oil; physical movement and social connection are also important as well. To this point, researchers followed 11,800 Spanish adults for 8.5 years monitoring their eating patterns, lifestyle, and health outcomes. Those most closely following a Mediterranean Diet were 18% less likely to develop depression over the 8.5-year study. Similarly, those with the most physical activity and social activity were 19% and 23% less likely to develop depression, respectively. However, a Mediterranean lifestyle, which encompasses diet, physical activity, and social activity, seemed to be most effective, as it was linked with a 50% lower risk of depression. 
Clinical Psychological Science. 2016 Nov. 4(6):1085-10093. (Sanchez-Villegas A et al.)

Full Fat Mediterranean Diet Linked with Good Health

A healthy diet need not restrict fat or flavor, at least in the case of the delicious and nutritious Mediterranean diet. Researchers at the Department of Veterans Affairs in the U.S. analyzed data from 56 studies (of at least 100 people in each study) to get a big picture view of the Mediterranean diet. The studies were all controlled trials (one of the strongest types of nutrition studies) and were included so long as the participants followed at least 2 of the 7 characteristics of a Mediterranean diet (such as lots of fruits and vegetables, or a preference for olive oil and other unsaturated fats). The scientists found that a Mediterranean diet (with no restriction on fat) may help prevent heart disease, breast cancer, and type 2 diabetes, but they did not find a significant reduction in mortality.
Annals of Internal Medicine. 2016 Jul 19. (Bloomfield HE et al.) [Epub ahead of print]

Fat in Plant Oils, Fatty Fish Better for Blood Sugar Regulation

Researchers from around the globe analyzed findings from 102 randomized clinical trials, encompassing 4,660 participants, to see how different types of fat (saturated, unsaturated, and polyunsaturated) and carbohydrates affect diabetes markers (including blood sugar, insulin production, and insulin sensitivity).  Polyunsaturated fats are found in fatty fish (salmon, trout, mackerel) and plant oils (soybean, sunflower, corn oil), while monounsaturated fats are found in olive and canola oil, and saturated fats are found in red meat and dairy products. The authors found that “substituting carbohydrate and saturated fat with a diet rich in unsaturated fat, particularly polyunsaturated fat, was beneficial for the regulation of blood sugar.” However, the authors did not test the effect of different types of carbohydrate sources (such as differentiating between whole grains, refined grains, or sugars).
PLOS Medicine. 2016 Jul 19;13(7):e1002087. (Imamura F et al.)