Past Week in Nutrition Science: This is an overview of interesting nutrition research published from Friday, Jan 8th, to Friday, Jan 15th, 2016.
Past Week in Nutrition Science (Jan 8th–Jan 15th)
Two articles were reviewed in the past week: one from Journals of Gerontology: Medical Sciences, and the other from the American Journal of Clinical Nutrition.
Summary: This 2-year, randomized, controlled trial examined the effects of long-term calorie restriction on predictors for longevity in healthy, non-obese men and women.
The study found that moderate calorie restriction improved several predictors for longevity, such as body weight, blood pressure, blood lipids, inflammation and thyroid hormones. Additionally, it slowed metabolism.
Summary: This randomized, controlled trial compared the effects of a standard DASH diet and a higher-fat, lower-carb DASH diet.
The study showed that the higher-fat DASH diet did not impair risk factors for heart disease, compared to the control. Also, its effects on blood pressure were similar to the conventional DASH diet.
New Research From Around the World
Tons of new research articles came out this week. Here is a selection of the most interesting ones, categorized by subject.
- Obesity and Weight Loss
- Blood Sugar Control and Diabetes
- Heart Health
- Metabolic Syndrome
- Appetite and Eating
- Bone Health
- Allergies and Immune Health
- Men’s Health
Obesity and Weight Loss
This randomized, controlled trial showed that taking 15 grams of yellow pea fiber each day, for 12 weeks, may cause small reductions in body weight and body fat by suppressing calorie intake.
Chitosan is a type of dietary fiber, produced from the shells of shrimp. It may support weight loss by suppressing fat absorption, but previous studies have provided conflicting results.
This randomized, controlled trial in overweight and obese people found that supplementing with chitosan, 2,500 mg per day for 90 days, reduced body weight by 6.5 lbs (3 kg), on average, compared to a placebo.
Blood Sugar Control and Diabetes
People with chronic kidney disease (CKD) are frequently insulin resistant. Scientists have suggested that vitamin E may help increase levels of insulin and improve insulin sensitivity in these individuals.
This observational study suggests that high levels of alpha-tocopherol, which is the most common form of vitamin E, may increase insulin sensitivity for people with CKD.
This prospective, observational study indicates that a high consumption of potatoes before pregnancy may increase the risk of gestational diabetes. On the other hand, eating other vegetables, whole-grain foods or legumes may reduce the risk.
Too much iron, a so-called iron overload, may damage the cells that produce insulin, increasing the risk of diabetes.
This observational study in women, who previously had diabetes during pregnancy, suggests that high iron intake may increase the risk of type 2 diabetes.
Resistant starch (RS) is a type of dietary fiber that may improve blood sugar control. This randomized, controlled trial showed that supplementing with 30 grams a day of RS from high-amylose maize, for 4 weeks, may increase insulin sensitivity.
Previous studies suggest that eating raw nuts may reduce the risk of heart disease. However, it is unclear whether this also applies to roasted and salted nuts.
This randomized, crossover study suggests that eating dry-roasted and lightly salted hazelnuts, 30 grams per day for 28 days, does not worsen blood pressure or the blood lipid profile, compared to raw hazelnuts.
This Cochrane review concludes that dietary fiber may improve some risk factors for heart disease, such as blood pressure and blood lipids.
However, studies are generally short-term and do not prove that high fiber intake reduces the incidence of heart disease events. Long-term, randomized, controlled trials are needed.
Previous studies suggest that constipation is associated with an increased risk of heart disease. This large, observational study supports earlier findings, indicating that low defecation frequency may increase people’s risk of heart disease.
This randomized trial suggests that a low-calorie diet is more effective than aerobic exercise for improving the blood lipid profile.
Lutein is a carotenoid antioxidant found in high amounts in kale and spinach. This meta-analysis and systematic review concludes that a higher intake of lutein may promote better heart health.
This large, observational study suggests that eating more whole fruits and vegetables may reduce the risk of high blood pressure.
Hemodialysis is a mechanical process that cleans the blood in patients with kidney disease. One of the side effects is a dysfunction of the lining of the blood vessels, which may lead to clogged arteries.
This randomized, controlled trial showed that drinking a cocoa beverage rich in cocoa antioxidants (flavanols), 900 mg per day for 30 days, improved blood vessel function, reduced blood pressure and increased heart rate.
This observational study in obese, Korean men indicates that a high intake of dairy products may reduce the risk of metabolic syndrome. Conversely, a high intake of calcium, without dairy, may increase the risk.
Lycopene is a carotenoid antioxidant found in high amounts in tomatoes and watermelon. This observational study shows that high levels of lycopene in blood are associated with a reduced risk of death in people with metabolic syndrome.
This observational study suggests that both low and excessive intakes of iodine may increase the risk of thyroid cancer.
Appetite and Eating
This study suggests that mindful attention to the hedonic properties of food may reduce calorie intake by affecting appetite.
L-rhamnose and inulin are simple carbohydrates that are resistant to digestion. They reach the colon intact, where they are fermented by bacteria.
This small, randomized trial found that neither L-rhamnose nor inulin had any effects on appetite following meals. However, they may improve blood sugar control.
Hesperidin is one of the most abundant antioxidant flavonoids found in citrus fruits. Previous studies suggest that it may prevent bone loss in female rats who have had their ovaries removed.
This small, randomized, crossover trial in postmenopausal women showed that supplementing with 500 grams of hesperidin may reduce bone loss when calcium supplements are taken as well. On its own, hesperidin had no effects.
Allergies and Immune Health
This observational study suggests that high milk consumption during pregnancy may reduce the child’s risk of becoming allergic to milk.
Plant sterols are a type of fat, resembling cholesterol, that are found in high amounts in vegetable oils. Stanols are a saturated type of plant sterols.
This randomized, controlled trial showed that supplementing with plant stanols, 4 grams every day for 4 weeks, improved immune function in asthma patients.
Erectile dysfunction is a problem characterized by an inability to initiate or maintain an erection. This observational study suggests that a diet rich in flavonoid antioxidants, from plant foods, may reduce the risk of erectile dysfunction.