Past Week in Nutrition Science (June 17–24th)

This is our weekly selection of recently published nutrition research.

Here are some of the most interesting findings this week:

Supplementing with heat-killed probiotics may have slight weight-loss benefits.
Certain flavonoid supplements may reduce your risk of catching a cold.
Adding 10 grams of extra virgin olive oil to a meal reduces blood sugar levels afterwards.
Supplementing with vitamin D may benefit people with chronic heart failure.
High intakes of saturated fat are associated with increased loss of cartilage in osteoarthritis.
Beta-glucan, a soluble fiber from barley, improves the blood lipid profile, possibly reducing the risk of heart disease.
Young Asian Scientist

Research Reviews

As usual, we reviewed two studies this past week: one examining the effects of heat-killed probiotics on weight loss and another about flavonoids and colds.

Review: Dead Probiotics Caused Weight Loss.

Article: Antiobesity effect of Pediococcus pentosaceus, LP28 on overweight subjects: a randomized, double-blind, placebo-controlled clinical trial.

Summary: This randomized controlled trial tested the effects of heat-killed probiotics (Pediococcus pentosaceus) on weight loss in overweight people.

The study showed that supplementing with dead probiotics caused slight weight loss, compared to a placebo. These findings suggest that probiotic bacteria contain bioactive compounds that provide benefits, even when they’re dead.

Review: Flavonoids Help Fight the Common Cold.

Article: Effect of Flavonoids on Upper Respiratory Tract Infections and Immune Function: A Systematic Review and Meta-Analysis.

Summary: This systematic review and meta-analysis of randomized controlled trials investigated the effects of flavonoids on upper respiratory tract infections (colds).

The study concluded that supplementing with certain types of flavonoids may help reduce the risk of catching a cold, possibly because of their anti-viral effects.

New Research from Around the World

Lots of new research came to our attention this week. Here are summaries of the most interesting or relevant studies, categorized by subject.

Obesity and Weight Loss
Blood Sugar Control and Diabetes
Heart Health
Appetite and Eating
Brain and Mental Health
Digestive Health
Muscles and Physical Performance
Arthritis
Allergies and Auto-Immune Disorders
Longevity and Healthy Aging
Vitamins, Minerals and Other Nutrients
1. Obesity and Weight Loss

Protein intake in early childhood and body composition at the age of 6 years: The Generation R Study.

This observational study in children suggests that a higher protein intake in early childhood is associated with higher body fat mass at the age of 6.

Animal protein was more strongly associated with later fat mass than vegetable protein. Additionally, this association was stronger in girls than boys.

Upregulation of inflammasome activity and increased gut permeability are associated with obesity in children and adolescents.

This observational study in obese and normal-weight children and adolescents indicates that obesity is associated with increased gut inflammation and permeability.

It is unclear whether this is caused by obesity itself, an unhealthy diet or if inflammation makes people predisposed to weight gain.

Impact of sugars and sugar taxation on body weight control: A comprehensive literature review.

This review concluded that sugar taxation, on its own, is an inefficient strategy to reduce obesity rates, even though sugar intake is a risk factor for obesity.

Late night overeating is associated with smaller breakfast, breakfast skipping and obesity in children. The Healthy Growth Study.

This observational study in children suggests that late night eating is associated with a smaller breakfast, breakfast skipping and obesity.

Effect of a high-fat Mediterranean diet on bodyweight and waist circumference: a prespecified secondary outcomes analysis of the PREDIMED randomised controlled trial.

This randomized controlled trial showed that following a high-fat Mediterranean diet supplemented with extra virgin olive oil or nuts caused more weight loss and less gain in abdominal fat, compared to a lower-fat control diet.

2. Blood Sugar Control and Diabetes

Extra virgin olive oil improves post-prandial glycemic and lipid profile in patients with impaired fasting glucose.

This randomized controlled trial in pre-diabetic individuals showed that taking 10 grams of extra virgin olive oil with a meal reduced blood sugar levels and increased the levels of insulin and glucagon-like peptide 1 (GLP-1).

Additionally, virgin olive oil significantly reduced triglyceride levels and apolipoprotein B-48. Taken together, these findings suggest that extra virgin olive oil improves blood sugar control in people with impaired fasting blood sugar.

Effect of low-glycemic-sugar-sweetened beverages on glucose metabolism and macronutrient oxidation in healthy men.

Inactivity reduces insulin sensitivity and fat oxidation (fat burning). This trial in healthy men compared the effects of drinking a sugar-sweetened beverage with a high-glycemic index (high-GI-SSB) to a low-GI-SSB during a 7-day period of inactivity.

The study showed that drinking a low-GI-SSB reduced the decline in insulin sensitivity during inactivity, compared to a high-GI-SSB. In contrast, the decline in fat oxidation was similar between groups.

Plasma concentrations of coffee polyphenols and plasma biomarkers of diabetes risk in healthy Japanese women.

Previous studies suggest that coffee may reduce the risk of type 2 diabetes. Researchers believe its high polyphenol content – mainly caffeic acid and chlorogenic acid – may be responsible for these benefits.

This observational study in Japanese women found that circulating levels of chlorogenic acid were associated with lower fasting blood sugar, HbA1c and CRP. In contrast, caffeic acid was only weakly linked with these biomarkers.

3. Heart Health

Effects of Vitamin D on Cardiac Function in Patients With Chronic HF The VINDICATE Study.

Heart failure occurs when the heart is not able to pump enough blood throughout the body. People with chronic heart failure are often deficient in vitamin D.

This controlled trial in patients with chronic heart failure and vitamin D deficiency showed that supplementing with 4,000 IU of vitamin D daily for one year significantly improved heart function.

Plasma Trimethylamine N -Oxide, a Gut Microbe–Generated Phosphatidylcholine Metabolite, Is Associated With Atherosclerotic Burden.

Previous observational studies suggest that high circulating levels of trimethylamine N-oxide (TMAO) increase the risk of heart disease. Since TMAO levels depend on certain types of gut bacteria, they are only a concern in some people.

This observational study in people with coronary artery disease showed that high fasting TMAO levels were associated with worsened disease development.

A systematic review and meta-analysis of randomized controlled trials of the effect of barley β-glucan on LDL-C, non-HDL-C and apoB for cardiovascular disease risk reduction.

Barley contains high amounts of beta-glucan, a type of viscous, soluble fiber that lowers blood cholesterol.

This systematic review and meta-analysis concluded that beta-glucan reduces levels of LDL-cholesterol and non-HDL cholesterol. These findings suggest that eating barley or supplementing with beta-glucan may help reduce the risk of heart disease.

4. Appetite and Eating

Associations between Restrained Eating and the Size and Frequency of Overall Intake, Meal, Snack and Drink Occasions in the UK Adult National Diet and Nutrition Survey.

To lose weight or improve health, some people avoid certain foods, ingredients or even whole food groups. When this behavior starts affecting people’s social flexibility, it is referred to as restrained eating.

This observational study in UK adults showed that restrained eaters tended to eat smaller meals, but meal frequency was slightly higher, compared to average.

5. Brain and Mental Health

Coffee intake and the incident risk of cognitive disorders: A dose-response meta-analysis of nine prospective cohort studies.

This meta-analysis of observational studies found a U-shaped association between coffee intake and cognitive disorders, such as dementia and Alzheimer’s disease.

The lowest risk was associated with 1–2 cups of coffee per day, whereas less than 1 cup per day or more than 3 cups per day were not significantly linked with cognitive disorders.

Dietary guanidinoacetic acid increases brain creatine levels in healthy men.

Guanidinoacetic acid (GAA) is an experimental dietary supplement, which is the natural precursor of creatine in the body. Creatine helps with the formation of ATP, an enzyme that transports energy within cells.

This randomized controlled trial showed that supplementing with 16-27 mg of GGA per pound (36–60 mg per kilogram) of body weight daily for 8 weeks increased brain creatine levels by 19.1%.

6. Digestive Health

Modulation of gut microbiota dysbioses in type 2 diabetic patients by macrobiotic Ma-Pi 2 diet.

Macrobiotic diets are based on the Asian yin-yang philosophy. They mainly consist of grains, vegetables and soy, encourage mindful eating and recommend against eating several types of foods and food groups, including processed foods.

This trial showed that the macrobiotic diet Ma-Pi 2 was more effective at reducing the counts of possible pro-inflammatory gut bacteria, compared to the control diet (diabetes diet). However, both diets were effective at treating gut dysbiosis.

Dairy Products, Dietary Calcium, and Risk of Inflammatory Bowel Disease: Results From a European Prospective Cohort Investigation.

Inflammatory bowel disease, including Crohn’s disease and ulcerative colitis, is characterized by inflammation in the digestive tract. The main symptoms are stomach pain, diarrhea and weight loss.

This observational study suggests that eating dairy products may reduce people’s risk of developing Crohn’s disease. However, dairy intake wasn’t significantly associated with ulcerative colitis.

7. Muscles and Physical Performance

Effects of powdered Montmorency tart cherry supplementation on acute endurance exercise performance in aerobically trained individuals.

This randomized controlled trial in endurance-trained athletes tested the effects of supplementing with 480 mg of powdered Montmorency tart cherries per day for 10 days surrounding a half-marathon race.

The study showed that supplementing with tart cherries improved race finish times and reduced pre-run soreness. Additionally, it improved antioxidant status and reduced markers of inflammation and muscle breakdown.

8. Arthritis

Dietary Fat and Progression of Knee Osteoarthritis Dietary Fat Intake and Radiographic Progression of Knee Osteoarthritis: Data from the Osteoarthritis Initiative.

Osteoarthritis (OA) is a degenerative joint disease characterized by the breakdown of cartilage in joints. The main symptoms are joint swelling, stiffness and pain.

This observational study suggests that a high fat intake, especially saturated fat intake, is associated with increased cartilage loss and OA. In contrast, high intakes of monounsaturated and polyunsaturated fats were linked with reduced OA progression.

9. Allergies and Auto-Immune Disorders

Influence of Alcohol Consumption on the Risk of Systemic Lupus Erythematosus among Women in the Nurses’ Health Study Cohorts.

Systemic lupus erythema (SLE) is an auto-immune disease. Similar to other auto-immune diseases, the body’s immune system attacks healthy tissues throughout the body. Symptoms include skin rash, fatigue, swollen joints, fever and mouth ulcers.

This prospective observational study in women found that drinking moderate amounts of alcohol – 5 grams of ethanol or half a drink per day – was linked to a lower risk of SLE.

10. Longevity and Healthy Aging

Association Between Hypovitaminosis D in Elderly Women and Long- and Short-Term Mortality—Results from the Osteoporotic Prospective Risk Assessment Cohort.

This observational study in 75-year old Swedish women found that low circulating vitamin D levels (below 50 nmol/l) were associated with a greater risk of death of all causes.

11. Vitamins, Minerals and Other Nutrients

A cross-sectional study on nutrient intake and -status in inflammatory bowel disease patients.

This study showed that people with inflammatory bowel disease (IBD) often limit their consumption of dairy products, processed meat, soft drinks, alcohol and fast food.

People with IBD also tended to be iron deficient and low in calcium and vitamin D. For those who eat little meat and dairy, supplementing with these nutrients might provide health benefits.