Past Week in Nutrition Science (March 11th–18th)

This is an overview of interesting nutrition research published from Friday, March 11th, to Friday, March 18th, 2016.

Bright Female Doctor Holding Green Apple

Research Reviews

As usual, we reviewed two articles in the past week: one from the Journal of Nutritionand the other from the International Journal of Obesity.

Review: Protein Reduces Appetite More Than Carbs and Fat.

Article: Protein-Enriched Liquid Preloads Varying in Macronutrient Content Modulate Appetite and Appetite-Regulating Hormones in Healthy Adults.

Summary: This randomized crossover trial examined the effects of protein, fat and carbs on self-rated appetite, appetite hormones and calorie intake.

As with most previous studies, the study showed that protein reduces appetite more than carbs and fat. On the other hand, fat appeared to be the least filling.

Review: Low-Calorie Sweeteners May Help You Lose Weight.

Article: Does low-energy sweetener consumption affect energy intake and body weight? A systematic review, including meta-analyses, of the evidence from human and animal studies.

Summary: This was a systematic review and meta-analysis of randomized controlled trials, observational studies and animal experiments that examined the effects of low-calorie sweeteners on calorie intake and body weight.

The overall conclusion was that low-calorie sweeteners do not lead to weight gain. In fact, they may reduce the risk of gaining weight, when replacing sugar.

New Research From Around the World

Every week, we scour the web for new articles on nutrition. Below is a summary of the most interesting or relevant articles, categorized by subject.

  1. Obesity and Weight Loss
  2. Blood Sugar Control and Diabetes
  3. Heart Health
  4. Cancer
  5. Appetite and Eating
  6. Brain and Mental Health
  7. Eyes and Vision
  8. Digestive Health
  9. Kidney and Urinary Health
  10. Bone Health
  11. Muscles and Physical Performance
  12. Infections and Immune Health
  13. Skin Health
  14. Pregnancy and Infant Health
  15. Contaminants
  16. Vitamins, Minerals and Other Nutrients

1. Obesity and Weight Loss

Matured hop extract reduces body fat in healthy overweight humans: a randomized, double-blind, placebo-controlled parallel group study.

Hops are a flower that provide beer with its bitterness and flavor. The bitter components include iso-alpha acids, which have been shown to reduce body fat in humans. However, they are quite bitter.

Matured hop extract (MHE) is much less bitter, and could be more suitable as a weight loss supplement. This randomized controlled trial showed that taking MHE, 35 mg of bitter acids for 3 months, significantly reduced body fat, especially belly fat.

Wheat gluten intake increases weight gain and adiposity associated with reduced thermogenesis and energy expenditure in an animal model of obesity.

This study found that adding large amounts of gluten (4.5%) into the diet of mice led to weight gain and fat buildup.

Explaining this, gluten reduced the amount of calories they burned. It’s unclear if these findings have any relevance for humans.

The effect of dietary approaches to stop hypertension (DASH) diet on weight and body composition in adults: a systematic review and meta-analysis of randomized controlled clinical trials.

The DASH diet was designed to lower blood pressure. It also contains a variety of foods that have been linked with a reduced risk of gaining weight.

This systematic review and meta-analysis of randomized controlled trials showed that following the DASH diet may be an effective way to lose weight. A low-calorie DASH diet led to even more weight loss than other low-calorie diets.

2. Blood Sugar Control and Diabetes

Glucose- and glycaemic factor-lowering effects of probiotics on diabetes: a meta-analysis of randomised placebo-controlled trials.

This meta-analysis of randomized controlled trials showed that supplementing with probiotics can significantly improve blood sugar control and insulin sensitivity for people with type 2 diabetes.

3. Heart Health

Impact of phenolic-rich olive leaf extract on blood pressure, plasma lipids and inflammatory markers: a randomised controlled trial.

Antioxidants like phenols may improve risk factors for heart disease. Olive leaves are especially rich in antioxidant phenols, such as oleuropein and hydroxytyrosol.

This randomized controlled trial in men with pre-hypertension found that supplementing with olive leaf extract — 136 mg of oleuropein and 6 mg of hydroxytyrosol every day for 6 weeks — improved blood pressure and blood lipids.

Effects of vitamin D on serum lipid profile in patients with type 2 diabetes: A meta-analysis of randomized controlled trials.

This meta-analysis of randomized controlled trials showed that supplementing with vitamin D may improve circulating levels of total cholesterol, triglycerides and LDL-cholesterol in patients with type 2 diabetes.

A meta-analysis of efficacy of Morus alba Linn. to improve blood glucose and lipid profile.

Some previous studies suggest that eating white mulberries may improve blood sugar levels and the blood lipid profile. However, the evidence is inconsistent.

This meta-analysis showed that white mulberries may improve blood sugar levels, but didn’t seem to have any significant benefits for the blood lipid profile.

Protective Effect of Myo-Inositol Hexaphosphate (Phytate) on Abdominal Aortic Calcification in Patients With Chronic Kidney Disease.

Phytate, found in all plant seeds, is an antinutrient. It reduces the absorption of certain minerals if they are eaten during the same meal. However, it’s also a strong antioxidant with several potential health benefits.

This observational study suggests that adequate intake of phytate may reduce or prevent calcification in abdominal arteries (CAA) in patients with chronic kidney disease. CAA is a risk factor for heart disease.

Heat-treated high-fat diet modifies gut microbiota and metabolic markers in apoe−/− mice.

This study suggests that heated fat may be less healthy than unheated fat. Mice fed a heat-treated, high-fat diet had enlarged spleens and a greater risk of developing heart disease.

Heat-treated fat also caused some changes in the gut microbiota, compared to unheated fat. Advanced glycation end products might be responsible for these effects. However, human studies are needed.

4. Cancer

Body mass index and breast cancer: analysis of a nation-wide population-based prospective cohort study on 1 393 985 Taiwanese women.

This large observational study in Taiwanese women suggests that high body mass index may increase the risk of developing breast cancer after menopause.

Alcohol Consumption-Related Metabolites in Relation to Colorectal Cancer and Adenoma: Two Case-Control Studies Using Serum Biomarkers.

This observational study found no significant association between circulating markers of alcohol consumption and colorectal cancer.

5. Appetite and Eating

Poverty, inequality, and increased consumption of high calorie food: Experimental evidence for a causal link.

This experiment suggests that when people view themselves as poor, or underprivileged, they are more likely to eat more and gain weight. The feeling of inequality may lead to anxiety, which can increase calorie intake.

Emotional eating as a mediator between depression and weight gain.

Observational studies indicate that depressed people are more likely to gain weight. This study indicates that depressed mothers are prone to emotional eating, or seeking relief from anxiety by eating.

This emotional eating may explain why depressed people have an increased risk of weight gain. However, the current study detected no significant links between depression and weight gain.

Is desire to eat in response to positive emotions an ‘obese’ eating style: Is Kummerspeck for some people a misnomer?

This experiment suggests that obese women do not eat in response to positive emotions. Only negative emotions seem to trigger eating.

This response to negative emotions is known as emotional eating, and is believed to explain, at least partly, why some people are prone to gaining weight.

Listening to music can influence hedonic and sensory perceptions of gelati.

This study suggests that music may influence the perceived taste of food. For example, when people liked a piece of music, or regarded it as neutral, the sweetness of chocolate ice cream was rated higher.

Conversely, if people listened to a piece of music they disliked, the ice cream was considered to be more bitter in taste.

6. Brain and Mental Health

Low dose resveratrol improves cerebrovascular function in type 2 diabetes mellitus.

Resveratrol is an antioxidant found in plant foods, such as the skin of red grapes and blueberries. It is best known for being found in red wine, and is believed to be responsible for some of its health benefits. However, the evidence is limited.

This randomized crossover trial in people with type 2 diabetes showed that taking a single dose of resveratrol temporarily improved blood flow in the brain. Maximum improvement was seen at the lowest dose tested, or 75 mg.

7. Eyes and Vision

Dietary folate, B vitamins, genetic susceptibility and progression to advanced nonexudative age-related macular degeneration with geographic atrophy: a prospective cohort study.

Macular degeneration is an eye disease that can impair vision or cause blindness. It is a major cause of vision loss among Americans.

This prospective observational study suggests that a high intake of folate may reduce the risk of age-related macular degeneration. However, this study couldn’t prove causality. Other nutrients in high-folate foods could be responsible.

8. Digestive Health

FODMAPs alter symptoms and the metabolome of patients with IBS: a randomised controlled trial.

FODMAPs are a fiber that may cause digestive issues, bloating, flatulence and stomach pain. They may also trigger symptoms of irritable bowel syndrome (IBS).

This randomized controlled trial showed that FODMAPs were directly linked to worsened IBS symptoms and changes in the gut microbiota.

9. Kidney and Urinary Health

Vitamin D and incident urinary incontinence in older adults.

This observational study suggests that high circulating levels of vitamin D improve bladder control in older adults.

10. Bone Health

Long-term effects of a very low carbohydrate weight loss diet and an isocaloric low-fat diet on bone health in obese adults.

Many people worry that very low-carb diets may affect bone health. However, there isn’t much evidence from long-term, human trials.

This randomized controlled trial of 118 obese adults showed that a 12-month, low-carb diet did not reduce bone mineral content, bone density or other markers or bone health, compared to a low-fat diet.

11. Muscles and Physical Performance

Dietary protein intake is associated with better physical function and muscle strength among elderly women.

This observational study found that dietary protein intake was linked with greater muscle strength and better physical function among elderly women.

12. Infections and Immune Health

Levels of innate immune factors in preterm and term mothers’ breast milk during the 1st month postpartum.

Prematurely born infants have immature immune systems, and are therefore prone to infections. However, breast milk contains several important immunologic factors that may protect premature infants.

This study showed that the breast milk of mothers who have premature babies contained greater amounts of some immune proteins than full-term breast milk.

Vitamin D Supplementation and the Risk of Colds in Patients with Asthma.

This randomized controlled trial showed that vitamin D supplementation, a single dose of 100,000 IU and then 4,000 IU/day for 28 weeks, did not affect the frequency or severity of colds in adults with asthma.

However, a sub-group analysis showed that supplementing with vitamin D increased the risk of cold among African Americans.

13. Skin Health

Vitamin D levels and atopic eczema in infancy and early childhood in Norway: a cohort study.

This observational study found no significant links between vitamin D levels and eczema in Norwegian children.

14. Pregnancy and Infant Health

Calcium Supplementation to Prevent Preeclampsia: Translating Guidelines into Practice in Low-Income Countries.

Pre-eclampsia is a pregnancy-associated disorder characterized by high blood pressure and other symptoms. It increases the risk of adverse pregnancy outcomes, and may lead to seizures (eclampsia) if untreated.

Calcium supplements are recommended during pregnancy to reduce the risk of preeclampsia. This review discusses how these recommendations should be translated into practice in low-income countries.

15. Contaminants and Food Safety

Endocrine-disrupting polychlorinated biphenyls in metabolically healthy and unhealthy obese subjects before and after weight loss: difference at the start but not at the finish.

Polychlorinated biphenyls (PCBs) are environmental contaminants that may disrupt the endocrine system. Studies have found that PCB levels are higher in metabolically unhealthy obese people, compared to healthy obese people.

This study found that PCBs did not differ depending on metabolic health. Also, the levels of PCBs did not seem to affect the health benefits of weight loss.

16. Vitamins, Minerals and Other Nutrients

Coffee, maté, açaí and beans are the main contributors to the antioxidant capacity of Brazilian’s diet.

This study found that Brazilian people get most of their antioxidants from coffee. Other major sources were maté tea, red wine, acai berries and beans.

Gastrointestinal modifications and bioavailability of brown seaweed phlorotannins and effects on inflammatory markers.

Brown varieties of seaweed, such as the knotted kelp, are a rich source of antioxidant phlorotannins.

This human trial showed that phlorotannins are absorbed into the bloodstream, mainly from the colon. Supplementing with phlorotannins also led to significantly higher circulating levels of an inflammatory marker called interleukin 8 (IL-8).

Protein “requirements” beyond the RDA: implications for optimizing health.

Growing evidence suggests that eating high-quality protein, even above the recommended daily allowance, may promote better health.

This review discusses the potential benefits of high protein consumption. The authors found no consistent evidence linking high protein intake with kidney disease or low bone mass.


Author: bryan nettles