Past Week in Nutrition Science: This is an overview of interesting nutrition research published from Friday, Dec 18th, to Thursday, Dec 31st, 2015.
Past Weeks in Nutrition Science (Dec 18th–Dec 31st)
In the past couple of weeks, we reviewed two articles: one from Diabetes Care, and the other from Obesity.
Summary: This was a randomized, controlled trial examining the effects of skipping breakfast on blood sugar control after meals.
The study found that skipping breakfast may cause higher blood sugar levels after meals later in the day and into the evening. Although these results are consistent with previous studies, they might not apply to people who regularly skip breakfast.
Summary: This randomized, controlled trial compared the effects of calorie-restricted, high-carb and moderate-carb diets on starvation response and body weight.
The main findings were that starvation response and weight loss were not affected by the amount of dietary carbs or the glycemic index.
New Research From Around the World
In the past couple of weeks, tons of new research articles were published. Below is a selection of some of the most interesting papers, categorized by subject.
- Obesity and Weight Loss
- Blood Sugar Control and Diabetes
- Heart Health
- Brain and Mental Health
- Appetite and Eating
- Digestive Health
- Kidney and Urinary Health
- Women’s Health
- Healthy Aging
- Nutrients, Vitamins and Minerals
Obesity and Weight Loss
It’s generally recommended that people trying to lose weight should drink a lot of water. However, water consumption has not been found to affect calorie and fat metabolism in all studies.
This clinical experiment showed that drinking 500 ml of water caused a slight increase in calories burned.
Observational studies suggest that good phosphorus status may reduce the risk of obesity. But until now, this had not been studied in a controlled trial.
This randomized, controlled trial showed that people who took phosphorus supplements 3 times a day for 12 weeks had a lower body weight at the end of the trial, compared to those who got a placebo.
This cross-sectional, observational study suggests that those who habitually clear their plates when eating are at a greater risk of becoming overweight.
The body’s timekeeping mechanism, called the body clock, regulates metabolic activities throughout the 24-hour day.
Disruption of the body clock, due to shift work or poor sleep, may contribute to the development of obesity. This review discusses the available evidence and reasons.
This observational study indicates that obese children and adolescents are 5 times more likely to become obese as adults, compared to those who were not obese.
This study, which measured sleep quality in 132 healthy students for 12 days, showed that poor sleep quality was associated with higher fat mass.
These results suggest that getting a good night’s sleep may help prevent weight gain and obesity.
Comparison of the effect of daily consumption of probiotic compared with low-fat conventional yogurt on weight loss in healthy obese women following an energy-restricted diet: a randomized controlled trial.
This 12-week, randomized controlled trial in overweight and obese women compared the effects of a probiotic yogurt and a standard low-fat yogurt on the effectiveness of a weight loss program.
There were no significant differences in weight loss across groups. However, eating a probiotic yogurt caused some improvements in blood lipids and insulin sensitivity, compared to the standard low-fat yogurt.
This randomized clinical trial compared the effects of drinking water or water sweetened with non-nutritive sweeteners (710 ml/day) on body weight during a 1-year weight loss program.
The study showed that those who drank water with non-nutritive sweeteners lost more weight, compared to those who got pure water.
Blood Sugar Control and Diabetes
Myo-inositol is a type of sugar alcohol produced by the human body and also found in cereals, green vegetables and meat.
According to this Cochrane review, myo-inositol supplementation is promising as a prevention for diabetes during pregnancy. However, the evidence is not good enough to recommend it for routine use.
Several previous studies showed that magnesium intake may improve insulin resistance and blood sugar clearance in patients with type 2 diabetes.
This observational study suggests that magnesium intake may reduce the risk of diabetes, supporting previous studies. However, this effect was only seen in women.
This observational study found no significant association between total fish consumption and the incidence of type 2 diabetes.
However, it suggests that high consumption of shellfish or fried fish may increase the risk of diabetes.
This observational study suggests that vitamin D status is not associated with type 1 diabetes in Finnish children.
This is a systematic review of observational studies investigating the association of dietary factors with diabetes during pregnancy, also called gestational diabetes.
It suggests that high intake of fruit, vegetables, whole grains and fish may protect against gestational diabetes. Conversely, a high intake of red or processed meat, refined grains and high-fat dairy may increase the risk.
This observational study examined the association of low-carb dietary patterns with the risk of type 2 diabetes among women with a history of diabetes during pregnancy.
The study suggests that a low-carb diet, high in protein and fat from animal sources, may increase the risk of type 2 diabetes. Conversely, a low-carb diet, high in protein and fat from plant sources, was not associated with an increased risk.
Poor magnesium status has been strongly associated with an increased risk of type 2 diabetes. Human trials have also shown that magnesium supplementation improves blood sugar control and insulin sensitivity.
This review discusses the available evidence and potential means. It also suggests magnesium deficiency in type 2 diabetes may be a part of a vicious cycle, since insulin resistance may deplete magnesium stores in the body.
This 6-week, randomized controlled trial showed that taking 1,000 mg of omega-3 fatty acids each day, along with 400 IU of vitamin E, benefits blood sugar control and blood lipids in pregnant women with diabetes.
This observational study suggests that the Mediterranean diet may reduce the risk of heart disease.
This prospective observational study indicates that high vitamin C intake, and overall diet quality, may reduce the risk of high blood pressure.
However, vitamin C from supplements was not associated with improved blood pressure. This indicates that vitamin C itself is not the cause for these improvements, but that other dietary or lifestyle factors are responsible.
Previous studies have shown that potassium supplementation may reduce blood pressure, especially when sodium intake is unrestricted.
This randomized, crossover trial found that supplementing with potassium for 4 weeks reduced blood pressure, even when sodium intake was restricted.
This cross-sectional, observational study suggests that drinking soft drinks is associated with higher blood pressure.
The association was stronger among those who drank diet sodas, compared with sugar-sweetened beverages.
Sesame oil and rice bran oil are high in unsaturated fatty acids as well as antioxidants, and have been associated with a reduced risk of heart disease.
This study showed that supplementing with a blend of sesame oil and rice bran oil may reduce blood pressure and improve the blood lipid profile of hypertensive patients.
This meta-analysis of observational studies indicates that moderate consumption of alcohol may reduce the risk of heart disease — specifically coronary artery disease — compared to abstaining or drinking too much.
The optimal intake was estimated to be 36 grams of ethanol per day.
This meta-analysis of observational studies suggests that a high intake of vitamin D may reduce the risk of bladder cancer.
This meta-analysis of observational studies indicates that the consumption of processed meat, and total red meat intake, is associated with an increased risk of colorectal cancer in both Japanese people and African Americans.
This association was strongest among those who were genetically predisposed to colorectal cancer, specifically those who had the NAT2 genotype.
This meta-analysis of observational studies suggests that the consumption of red meat and processed meat is not associated with prostate cancer risk.
This clinical study showed that for colorectal cancer patients, taking 2 g/day of fish oil during the first 9 weeks of chemotherapy may slow down cancer growth.
Their potential health benefits have been studied in test-tube experiments, mainly focusing on their anticancer effects. This review summarizes the available evidence.
This meta-analysis of observational studies suggests that drinking coffee may reduce the risk of cutaneous melanoma, one of the most aggressive forms of skin cancer.
This meta-analysis of observational studies indicates that drinking large amounts of coffee may, over time, increase the risk of stomach cancer.
Brain and Mental Health
This observational study suggests that eating lots of fruit, vegetables and fiber may reduce symptoms of depression in Japanese workers.
This controlled trial showed that losing weight, through a dietary weight loss program, improved cognition in obese, elderly individuals with mild cognitive impairment.
This was a randomized controlled trial in new mothers suffering from depression after delivery, which is known as postpartum depression.
The study showed that supplementing with iron, 50 mg of elemental iron every day for 6 weeks from the first week after delivery, improved their iron stores and reduced symptoms of depression.
Appetite and Eating
Food labels are considered an effective way to improve people’s food choices, and reduce the risk of chronic disease and obesity.
This meta-analysis of randomized studies supports this, suggesting that food labeling may help consumers select healthier products. Interpretive or traffic light labels are possibly the most helpful.
This article discusses three experiments on how people perceive portion sizes. It concluded that when people are routinely exposed to large portion sizes, they start perceiving them as normal. However, this did not apply to snack food intake.
Crohn’s disease is a chronic inflammatory disease that affects the digestive system. This meta-analysis of observational studies suggests that vitamin D status is associated with Crohn’s disease.
Not only are patients with Crohn’s disease more likely to be vitamin D deficient, but the severity of the disease also seems to be greater in those with the lowest levels of vitamin D.
Antibiotics may disrupt the normal balance of bacteria in the digestive system, causing increased growth of undesirable bacteria. This may lead to antibiotic-associated diarrhea.
This Cochrane review of clinical trials suggests that probiotics may prevent antibiotic-associated diarrhea in children.
Kidney and Urinary Health
This Cochrane review concludes that there is no evidence that probiotics reduce urinary tract infections in adults and children.
Protein Diet Restriction Slows Chronic Kidney Disease Progression in Non-Diabetic and in Type 1 Diabetic Patients, but Not in Type 2 Diabetic Patients: A Meta-Analysis of Randomized Controlled Trials Using Glomerular Filtration Rate as a Surrogate.
This meta-analysis of randomized, controlled trials suggests that eating less protein, or restricting protein intake, may slow the development of chronic kidney disease in non-diabetic people and those with type 1 diabetes.
Conversely, protein restriction does not seem to improve kidney disease in patients with type 2 diabetes.
Cervical intraepithelial neoplasia (CIN) is a condition characterized by abnormal growth of the cells lining the cervix. It is not a type of cancer, but may potentially develop into cancer if left untreated.
This randomized controlled trial showed that supplementing with folate, 5 mg/day for 6 months, may help treat CIN stage 1, compared to a placebo. Additionally, it improved insulin sensitivity and reduced oxidative stress.
This randomized, controlled trial compared the effects of a diet with a low glycemic index (low-GI diet) and a conventional high-fiber diet (HF-diet) on pregnancy outcomes in women at a high risk of getting diabetes during pregnancy.
There was no difference in pregnancy outcomes across groups, as both the low-GI diet and the HF-diet had similar health effects.
Human milk is generally low in vitamin D. This randomized, controlled trial is the first study to examine the effects of supplementing with vitamin D during pregnancy on vitamin D levels in breast milk after delivery.
The study showed that when pregnant women take 2,000 IU/day of vitamin D, from week 36 of pregnancy until delivery, the vitamin D levels in their milk were higher than with a placebo for at least 2 months afterwards.
Previous studies in both animals and humans indicate that reducing protein intake may help prevent many age-related diseases and increase longevity.
This review concludes that excessive protein consumption may have detrimental effects over time. However, eating too little protein is unhealthy as well. The optimal intake is somewhere in between and may increase with age.
Nutrients, Vitamins and Minerals
Previous studies have shown that exercise may prevent the adverse effects of excessive fructose consumption.
This study confirmed previous findings. Exercising immediately after consuming fructose increased its oxidation and decreased fructose storage. Conversely, exercising before consuming fructose had no effects.