This is an overview of interesting nutrition research published from Friday, May 27th, to Friday, June 3rd, 2016.
Here are some of the most interesting findings this week:
- Some people are more prone to weight gain than others.
- Metabolic syndrome reduces vitamin E bioavailability.
- The content of your breakfast is important.
- Eating breakfast may have short-term cognitive benefits.
- Flavonoid antioxidants may help prevent infections.
- Causes of folate deficiency during pregnancy.
- Risk factors for malnutrition in older adults.
Research Reviews
This week we reviewed two papers: one examining the link between starvation response (thriftiness) and obesity and the other looking at vitamin E bioavailability among people with metabolic syndrome.
Review: Thriftiness: Another Piece of the Obesity Puzzle.
Article: Lower core body temperature and greater body fat are components of a human thrifty phenotype.
Summary: This study showed that some people are better at conserving calories during periods of fasting (or starvation).
Not only does this make them more likely to survive a famine, it also makes them prone to gaining fat when food is abundant.
Review: The Bioavailability of Vitamin E is Lower in Metabolic Syndrome.
Summary: This randomized, crossover trial examined the bioavailability of vitamin E among people with metabolic syndrome.
Metabolic syndrome reduces vitamin E bioavailability, but the underlying cause is not entirely clear. Increased oxidative stress or inflammation may play a role.
New Research From Around the World
Lots of new papers 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
- Cancer
- Brain and Mental Health
- Digestive Health
- Liver Health
- Muscles and Physical Performance
- Infections and Immune Health
- Skin Health
- Pregnancy and Infant Health
- Longevity and Healthy Aging
- Vitamins, Minerals and Other Nutrients
1. Obesity and Weight Loss
Polydextrose (PD) is a type of soluble fiber commonly used in processed food to replace sugar, increase its fiber content and reduce its calorie content.
This controlled trial in Chinese men showed that eating high-protein soybean curd, with or without PD, and low-protein soybean curd, with PD, reduced calorie intake at a later meal, compared to the low-protein curd alone.
This review looked at the evidence linking breakfast consumption with obesity, while focusing on the nutritional composition of breakfast.
It found that based on observational data, no strong conclusions can be made about the importance of breakfast for preventing obesity.
This scientific review discussed the evidence linking breakfast with a healthy body weight, focusing on intervention studies. Overall, the evidence is mixed and weak.
However, growing evidence suggests that a breakfast high in fiber and protein may improve body weight more than other breakfasts. Additionally, it may be better if most of the daily calories are consumed early in the day.
2. Blood Sugar Control and Diabetes
Effect of fat type in baked bread on amylose–lipid complex formation and glycaemic response.
The interaction of carbs (starch) and fat in bread may form so-called amylose-lipid complexes (ALC). These complexes have been associated with reduced digestibility of starch. They may also improve its glycemic index.
This study showed that adding fat to a bread recipe significantly increased the amount of ALC and reduced the rise in blood sugar after eating the bread. Coconut or olive oil led to higher amounts of ALC, compared to butter or grapeseed oil.
This review of randomized controlled trials suggests that eating breakfast may improve blood sugar control throughout the day. This especially applies to low-glycemic breakfasts that are high in fiber and/or protein.
This observational study showed that a higher dietary quality, evaluated using the Healthy Eating Index 2005, was linked with an improved blood sugar control in children and adolescents with type 1 diabetes.
Specifically, high intake of whole plant foods, fiber, carbs, low-glycemic foods and unsaturated fat were associated with lower blood sugar levels.
3. Heart Health
Atherosclerosis is a disease of the arteries, the blood vessels that carry blood from the heart. It is characterized by fat accumulation (plaque buildup) on their inner surface, and they may eventually become clogged.
This observational study suggests that a high intake of polyunsaturated fat and a low-glycemic diet does not reduce the risk of high-risk atherosclerotic plaques.
4. Cancer
This observational study showed that a high vitamin C intake from foods (but not supplements) was linked with a higher risk of developing breast cancer.
5. Brain and Mental Health
The Effects of Breakfast and Breakfast Composition on Cognition in Adults.
This scientific review examined the available evidence linking breakfast consumption with mental performance or cognition in adults. The reviewers broadly defined breakfast as a meal after a fasting period of 8 hours or longer.
Overall, the evidence suggests that eating breakfast may slightly improve memory and attention in healthy adults in the short-term.
Breakfast is believed to positively affect cognition and school performance among children. Yet it’s the most frequently skipped meal, especially among adolescents.
This systematic review looked at the evidence linking breakfast with mental performance among children and adolescents. Overall, the results suggest that eating breakfast may have short-term benefits for cognition, compared to fasting.
6. Digestive Health
Parents or caregivers sometimes pre-chew food for infants. In the US, this practice is most common among African-Americans and Alaska Natives.
This observational study in 10-month old infants showed that those who ate pre-chewed food were at a higher risk of diarrhea. Other factors linked with a higher diarrhea risk included eating lots of sweets and dairy. Breastfeeding reduced the risk.
7. Liver Health
Healthy dietary pattern is inversely associated with non-alcoholic fatty liver disease in elderly.
Non-alcoholic fatty liver disease (NAFLD) is characterized by an accumulation of fat in the liver. It is associated with metabolic syndrome. If untreated, it may damage the liver over time, leading to a serious condition known as cirrhosis.
Older age is a risk factor for NAFLD. This observational study in elderly people showed that a healthy dietary pattern was associated with a lower risk of NAFLD.
8. Muscles and Physical Performance
Previous studies suggest that supplementing with betaine (trimethylglycine) may increase muscle mass in livestock and improve muscle performance in humans. However, it is unclear if betaine has any effects on muscle mass in humans.
This observational study linked higher circulating levels of betaine to a higher lean body mass in middle-aged and elderly Chinese adults, especially men.
9. Infections and Immune Health
Flavonoids are a subcategory of polyphenol antioxidants found in fruits, vegetables and other plant foods.
This systematic review of randomized controlled trials in healthy adults found that supplementing with flavonoids reduced the incidence of upper respiratory tract infections by 33%, compared to a placebo.
10. Skin Health
Vitamin D treatment for connective tissue diseases: hope beyond the hype?
Connective tissue diseases (CTDs) are a category of health disorders that affect the skin, bones and joints. Previous studies show that vitamin D deficiency is common among people with CTDs.
This review discussed the potential effectiveness of vitamin D supplements in the treatment of CTDs. However, the authors concluded that the evidence is limited and further high-quality trials are needed before any solid conclusions can be reached.
11. Pregnancy and Infant Health
Spina bifida is a birth defect associated with folate deficiency during pregnancy. It is becoming more common in Japan. This observational study examined the determinants of folate status in pregnant Japanese women during the first trimester.
Four factors were identified as a significant cause of poor folate status: young age, low educational level, low annual income and smoking. In contrast, supplementing with folic acid was the strongest predictor of good folate status.
12. Longevity and Healthy Aging
This systematic review of observational studies examined the risk factors for malnutrition in adults, aged 65 and older. 6 studies were included in the analyses.
The following risk factors have been identified: old age, institutionalization, use of 4 or more medications, general health decline, decline in physical function, constipation, cognitive decline, depression and poor appetite, to name a few.
This prospective observational study in older, community-dwelling adults showed that a higher intake of fruits and vegetables was associated with a lower risk of frailty.
The association may be caused by other healthy lifestyle factors linked with fruit and vegetable consumption. For example, those who consumed the lowest amounts also had the lowest physical activity levels.
13. Vitamins, Minerals and Other Nutrients
Polyphenols are a large category of antioxidants found in plants. They have been associated with a variety of health benefits. This observational study found that the main foods contributing to people’s polyphenol intake were coffee and fruits.
Subgroups of polyphenols also differed between dietary patterns, with flavonoid intake highest among pesco-vegetarians and phenolic acid intake (mainly from coffee) highest among non-vegetarians.
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