Past Week in Nutrition Science: This is an overview of interesting nutrition research published from Friday, January 15th, to Friday, January 22nd, 2016.

Isolated Trans Fats And Chitosan Supplements

Research Reviews

In the past week, we reviewed two research articles: one from the American Journal of Clinical Nutrition and the other from the Nutrition Journal.

Review: Isolated Trans Fats are Unhealthy, Regardless of the Source.

Study: Vaccenic acid and trans fatty acid isomers from partially hydrogenated oil both adversely affect LDL cholesterol: a double-blind, randomized controlled trial.

Summary: This clinical trial compared the effects of synthetic and natural trans fatty acids on the blood lipid profile.

The main finding was that vaccenic acid (the most common natural trans fat) and industrially produced trans fats both adversely affected the blood lipid profile.

Review: Chitosan Supplements May Cause Weight Loss.

Study: Single-blind, placebo controlled randomised clinical study of chitosan for body weight reduction.

Summary: This randomized, controlled trial examined the effectiveness of 2,500 mg of chitosan on weight loss.

The study showed that supplementing with chitosan may lead to significant weight loss, apparently without any changes in diet or physical activity.

New Research From Around the World

Plenty of research articles and reviews came out this week. Below is a selection of the most interesting or relevant papers, categorized by subject.

1. Obesity and Weight Loss

Clinical effectiveness of very-low-energy diets in the management of weight loss: a systematic review and meta-analysis of randomized controlled trials.

Official guidelines generally suggest that very-low calorie diets (VLEDs) can lead to adverse health effects, such as as rapid post-diet weight regain.

This meta-analysis of randomized, controlled trials concludes that VLEDs appear to be tolerable, and have less adverse effects than the guidelines suggest.

Mediterranean Dietary Pattern in Pregnant Women and Offspring Risk of Overweight and Abdominal Obesity in Early Childhood: The INMA Cohort Study.

Previous studies in animals suggest that the diet of pregnant mothers may affect their offspring’s risk of becoming obese, regardless of the mother’s weight.

This observational study in Spanish mothers and children indicates that there is no link between the mother’s adherence to the Mediterranean diet and the child’s risk of obesity. However, the diet was associated with smaller waist circumference.

Can We Prevent Obesity-Related Metabolic Diseases by Dietary Modulation of the Gut Microbiota?

This review discusses the possible role of gut bacteria, also called the gut microbiota, on the development of obesity and obesity-related diseases.

It speculates that abnormal gut microbiota may be a cause or consequence of obesity, or maybe a bit of both. It also discusses potential dietary ways to change the gut environment and treat obesity.

Effects of low-carbohydrate diets v. low-fat diets on body weight and cardiovascular risk factors: a meta-analysis of randomised controlled trials.

Previous studies comparing the effectiveness of low-carb and low-fat diets in reducing heart disease risk or body weight have provided inconsistent results.

This meta-analysis of randomized, controlled trials suggests that low-carb diets may lead to greater weight loss than low-fat diets. Low-carb diets may also lead to a greater increase in LDL-cholesterol and HDL-cholesterol.

Oral intake of a combination of glucosyl hesperidin and caffeine elicits an anti-obesity effect in healthy, moderately obese subjects: a randomized double-blind placebo-controlled trial.

Previous studies in mice indicate that a combination of caffeine and glucosyl hesperidin (GH) may decrease the accumulation of body fat.

This randomized, controlled trial showed that taking GH (500 mg) and caffeine (50–75 mg), every day for 12 weeks, significantly reduced belly fat, compared to a placebo.

A comparison of a behavioral weight loss program to a stress management program: A pilot randomized controlled trial.

Mental stress is a significant risk factor for obesity. This is because many people seek stress relief by eating. This small, randomized, controlled trial compared the effectiveness of a stress management program (SMP) and a weight loss program.

The weight loss program caused significantly more weight loss than the SMP. However, the SMP improved blood pressure, stress and depression.

2. Blood Sugar Control and Diabetes

Effects of the internal circadian system and circadian misalignment on glucose tolerance in chronic shift workers.

Previous studies have shown that shift work is a risk factor for diabetes. This randomized, crossover trial in healthy shift workers supported previous studies.

Shift work impairs blood sugar control by disrupting the body clock and causing circadian misalignment. The study also shows that blood sugar control is impaired later in the day, or in the so-called “biological evening.”

Can Walnuts Reduce Diabetes Risk? If So, in Whom?

Previous observational studies suggest that walnuts may protect against type 2 diabetes. This observational study suggests that these benefits are greater in Hispanics and African Americans, compared to non-hispanic European Americans.

Associations of Dietary Carbohydrates and Carbohydrate Subtypes with Diabetes Risk Factors in the Diabetes Prevention Program.

This observational study suggests that eating high amounts of vegetables and fiber, and limiting the intake of sugary soda and candy, may protect against type 2 diabetes.

3. Heart Health

Very-High-Fat and Low-Fat Isocaloric Diets Exert Similar Metabolic Benefits but Different Temporal Effects on Cardiometabolic Risk Markers.

Low-carb, very-high-fat diets are effective for weight loss, yet previous studies indicate that they may worsen heart disease risk factors.

This 12-week, randomized trial compared the effects of a low-carb, very-high-fat diet and a high-carb, low-fat diet on risk factors for heart disease. Both diets improved body composition and didn’t worsen any risk factors for heart disease.

Dietary Patterns and Blood Pressure in Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

This meta-analysis of randomized, controlled trials estimated the effects of different diets on blood pressure.

The study indicates that diets rich in fruit, vegetables, whole grains, legumes, seeds, nuts, fish and dairy may reduce blood pressure. Diets high in meat, candy and alcohol may increase blood pressure.

Maternal dietary patterns during pregnancy and offspring cardiometabolic health at age 6 years: The Generation R study.

This observational study suggests that the dietary patterns of pregnant mothers are not associated with the heart and metabolic health of their children when they are 6 years old.

A Randomized Study of the Effects of Additional Fruit and Nuts Consumption on Hepatic Fat Content, Cardiovascular Risk Factors and Basal Metabolic Rate.

This randomized trial compared the effects of two high-calorie diets on metabolic rate and risk factors for heart disease. One of the diets provided extra calories from fruit, whereas the other diet provided extra calories from nuts.

Weight gain was similar in both groups. Increased fruit intake seems to be safe, and did not increase liver fat or worsen any risk factors for heart disease. However, high fruit intake increased insulin levels.

The association between dietary saturated fatty acids and ischemic heart disease depends on the type and source of fatty acid in the European Prospective Investigation into Cancer and Nutrition-Netherlands cohort.

This observational study indicates that a high intake of saturated fat does not raise heart disease risk. However, this association may depend on the amounts and proportions of different fats in the diet.

4. Cancer

Plasma carotenoids, vitamin C, tocopherols, and retinol and the risk of breast cancer in the European Prospective Investigation into Cancer and Nutrition cohort.

This observational study indicates that high intake of beta-carotene and alpha-carotene may reduce the risk of breast cancer.

5. Appetite and Eating

Energy Contents of Frequently Ordered Restaurant Meals and Comparison with Human Energy Requirements and US Department of Agriculture Database Information: A Multisite Randomized Study.

This study suggests that food eaten in restaurants may contribute to obesity. Portion sizes are generally large and the food is often rich in calories.

Advertising as a cue to consume: a systematic review and meta-analysis of the effects of acute exposure to unhealthy food and nonalcoholic beverage advertising on intake in children and adults.

This meta-analysis indicates that food advertising may increase food intake in children, but not in adults.

6. Brain and Mental Health

Examining the potential clinical value of curcumin in the prevention and diagnosis of Alzheimer’s disease.

Curcumin is the main active ingredient in turmeric, a popular Indian spice. Previous studies suggest that it may have beneficial effects on neural function, possibly delaying neurodegenerative diseases like Alzheimer’s.

This review discusses the available evidence. In short, clinical studies indicate limited benefits of curcumin supplementation for Alzheimer’s. This is possibly because its bioavailability is relatively poor.

Clinical improvement following vitamin D3 supplementation in Autism Spectrum Disorder.

This clinical trial suggests that vitamin D deficiency may contribute to autism severity. Vitamin D levels are lower in children with autism than healthy children. Additionally, vitamin D3 supplements appeared to improve symptoms in autistic children.

Coffee induces vascular endothelial growth factor (VEGF) expression in human neuroblastama SH-SY5Y cells.

Vascular endothelial growth factor (VEGF) is a protein formed in the body that may protect neurons and stimulate their growth.

This test-tube experiment suggests that coffee may increase VEGF formation, which may contribute to coffee’s beneficial effects on neural disorders like Parkinson’s and Alzheimer’s disease.

Evaluation of Dietary Nutrients in Relation to Clinical Outcomes in Chronic-Progressive Multiple Sclerosis.

Multiple sclerosis (MS) is a neurodegenerative disease. It’s characterized by a variety of neurological symptoms, ranging from mental problems to impaired eyesight, muscle weakness and lack of coordination.

This study suggests that increased fiber intake may help improve MS. This may be explained by the beneficial effects of fiber on the gut bacteria, which may reduce systemic inflammation.

7. Lung Health

Dietary anthocyanin intake and age-related decline in lung function: longitudinal findings from the VA Normative Aging Study.

Anthocyanins are a group of antioxidant flavonoids that are responsible for the vibrant colors of many flowers and fruits. This observational study suggests that a high dietary intake of anthocyanins may improve lung function in older people.

8. Skin Health

Skin-Whitening and Overall Skin Tone-Improving Effects of Oral Supplementation with Lutein and Zeaxanthin Isomers: A Randomized, Double-Blind, Placebo-Controlled Trial.

Lutein and zeaxanthin are carotenoid antioxidants. This randomized, controlled trial showed that supplementing with lutein and zeaxanthin for 12 weeks improved skin tone, compared to a placebo.

Additionally, it improved the participants’ tolerance to sunlight, reducing the risk of sunburns. At the same time, lutein and zeaxanthin appeared to reduce skin pigmentation, causing skin whitening.

9. Muscles and Physical Performance

Vitamin D is associated with cardiopulmonary exercise capacity: results of two independent cohorts of healthy adults.

This observational study suggests that high circulating levels of vitamin D may increase people’s endurance.

The effects of a high protein diet on indices of health and body composition – a crossover trial in resistance-trained men.

This randomized trial showed that taking 3.3 grams of protein per kg of body weight, for 8 weeks, did not affect body composition, blood lipids, blood sugar or kidney function, compared to supplementing with 2.6 grams.

10. Pregnancy and Infant Health

Vitamin D supplementation for women during pregnancy.

This Cochrane review concluded that supplementing with vitamin D may reduce the risk of premature deliveries, high blood pressure and low birth weight.

However, the number of high-quality studies is limited, and no strong conclusions can be made about the safety and usefulness of these supplements for pregnant women.

11. Diets

Health Effects of 3-Day Fruit and Vegetable Juice Fasting.

This study examined the health effects of 3-day juice fasting. The fasting led to weight loss, decreased oxidation and increased circulating levels of nitric oxide. Previous studies have associated similar changes with improved heart health.

12. Nutrients, Vitamins and Minerals

Public Policy and Folic Acid Fortification: Great Harm or Help?

Folic acid is a synthetic form of vitamin B9, and the body may have trouble converting it into a biologically active form.

Many studies indicate that high levels of un-metabolized folic acid may cause harm, and this review discusses those potentially harmful effects.

Removing Potatoes from Children’s Diets May Compromise Potassium Intake.

This study suggests that potatoes are an important dietary source of potassium for many people, especially children.

Essential Nutrient Interactions: Does Low or Suboptimal Magnesium Status Interact with Vitamin D and/or Calcium Status?

The ratio of magnesium and calcium may have relevance for health, and adequate magnesium is necessary for the biosynthesis of vitamin D in the body.

This review discusses the potential interactions between magnesium status and vitamin D or calcium.

Consequences of a high phosphorus intake on mineral metabolism and bone remodeling in dependence of calcium intake in healthy subjects – a randomized placebo-controlled human intervention study.

This randomized, controlled trial showed that a high phosphorus intake has no effect on circulating levels of phosphate in blood. Additionally, high phosphorus intakes seem to adversely affect calcium metabolism.