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
In the past week, we reviewed two research articles: one from the American Journal of Clinical Nutrition and the other from the Nutrition Journal.
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.
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.
- Obesity and Weight Loss
- Blood Sugar Control and Diabetes
- Heart Health
- Appetite and Eating
- Brain and Mental Health
- Lung Health
- Skin Health
- Muscles and Physical Performance
- Pregnancy and Infant Health
- Nutrients, Vitamins and Minerals
1. OBESITY AND WEIGHT LOSS
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.
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.
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.
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.
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.
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
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.”
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.
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
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.
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.
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.
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.
5. APPETITE AND EATING
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.
This meta-analysis indicates that food advertising may increase food intake in children, but not in adults.
6. BRAIN AND MENTAL HEALTH
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.
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.
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.
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
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
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
This observational study suggests that high circulating levels of vitamin D may increase people’s endurance.
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
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.
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
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.
This study suggests that potatoes are an important dietary source of potassium for many people, especially children.
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.
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.