This is an overview of interesting nutrition research published from Friday, March 11th, to Friday, March 18th, 2016.
As usual, we reviewed two articles in the past week: one from the Journal of Nutritionand the other from the International Journal of Obesity.
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.
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.
- Obesity and Weight Loss
- Blood Sugar Control and Diabetes
- Heart Health
- Appetite and Eating
- Brain and Mental Health
- Eyes and Vision
- Digestive Health
- Kidney and Urinary Health
- Bone Health
- Muscles and Physical Performance
- Infections and Immune Health
- Skin Health
- Pregnancy and Infant Health
- Vitamins, Minerals and Other Nutrients
1. Obesity and Weight Loss
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.
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 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
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
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.
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.
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.
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.
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.
This large observational study in Taiwanese women suggests that high body mass index may increase the risk of developing breast cancer after menopause.
This observational study found no significant association between circulating markers of alcohol consumption and colorectal cancer.
5. Appetite and Eating
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.
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.
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.
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
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
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
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
This observational study suggests that high circulating levels of vitamin D improve bladder control in older adults.
10. Bone Health
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
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
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.
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
This observational study found no significant links between vitamin D levels and eczema in Norwegian children.
14. Pregnancy and Infant Health
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
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
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.
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).
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.