Past Week in Nutrition Science (July 22nd–29th)
This is our weekly selection of recently published studies and reviews in nutrition. Here are some of the most interesting findings this week:
- Eating prebiotic fiber leads to succinate formation in the digestive tract, improving blood sugar control.
- Eating potatoes is not consistently linked to an increased risk of obesity, heart disease and diabetes.
- Infants frequently fed during the nighttime are at an increased risk of obesity.
- Reviews of Garcinia Cambogia products show minimal benefit for weight loss
- Eating less fructose significantly improves the blood lipid profile.
- A diet low in advanced glycation end-products improves the blood lipid profile and reduces inflammation in diabetic people.
- Supplementing with vitamin D may improve symptoms of irritable bowel syndrome.
This week we reviewed two articles: one about the effects of potatoes on obesity, diabetes and heart disease and another examining the role of prebiotic fiber and succinate in blood sugar control.
Summary: This was a systematic review and meta-analysis of studies examining the effects of potatoes on weight gain, type 2 diabetes and heart disease.
The study showed that potatoes are not consistently associated with an increased risk of weight gain, obesity, type 2 diabetes or heart disease in healthy people. However, French fries appear to be unhealthy in high amounts.
Summary: This was a series of interventional studies in rats and mice. They examined the role of prebiotic fiber and succinate in blood sugar control.
The studies showed that when certain gut bacteria ferment prebiotic fiber, they produce succinate. Succinate activates intestinal gluconeogenesis, which improves blood sugar control.
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.
1. Obesity and Weight Loss
This observational study suggests that poor diet quality during pregnancy increases the risk of excessive fat mass (adiposity) in newborns.
This association was independent of the mother’s total calorie intake or body mass index before pregnancy.
This observational study in 12-month-old infants showed that frequent nighttime feeding was linked to increased fat gain and risk of overweight in early childhood.
This observational study showed that eating pasta as a component of the Meditarrenean diet was associated with reduced body mass index, waist circumference and a lower risk of obesity.
2. Blood Sugar Control and Diabetes
Previous observational studies indicate that high meat consumption may increase the risk of type 2 diabetes (T2D).
This observational study supports earlier evidence. It showed that meat consumption, especially processed meat, was associated with an increased risk of developing T2D.
This randomized controlled trial in women with diabetes during pregnancy examined the health effects of supplementing with a multispecies probiotic mixture for 8 weeks.
Taking probiotics led to a significant decrease in several inflammatory markers. Additionally, insulin levels and insulin sensitivity was improved in the probiotic group, compared to the placebo.
3. Heart Health
This observational study suggests that consuming 2–6 grams of ginger per day was linked to a reduced risk of high blood pressure and heart disease.
This 9-day study in obese children with metabolic syndrome examined the effects of reducing fructose intake (from 12 to 4% of daily calories) on the blood lipid profile.
Eating less fructose led to a significant improvement in the blood lipid profile, potentially reducing the risk of heart disease.
This randomized controlled trial examined how eating salmon affects the fatty acid content of pregnant women’s red blood cells.
From week 20 of pregnancy until delivery, the women ate 150 grams of salmon twice per week. The salmon did not significantly change the fatty acid content of their blood, compared to following a diet low in fatty fish.
Melanoma is more serious than other types of skin cancer. Other types of skin cancer are often referred to as non-melanoma skin cancers and include basal cell carcinoma (BCC) and squamous cell carcinoma.
This meta-analysis of observational studies concluded that drinking coffee may protect against BCC, but the effect is moderate. These findings need to be confirmed in randomized controlled trials.
This meta-analysis of observational studies concluded that being overweight or significantly obese increases the risk of developing cancer in the gallbladder and bile duct.
This observational study suggests that eating a lot of marine, omega-3 fatty acids reduces the risk of death among people who have colorectal cancer.
5. Appetite and Eating
This systematic review and meta-analysis of randomized trials concluded that the marketing of unhealthy foods and beverages makes children more likely to select them when given a choice.
This study in women showed that losing weight caused a shift in food preferences. Specifically, losing weight led to an increased preference for foods with a lower sucrose and fat content.
However, the nutrient composition of the weight-loss diet (low-fat vs low-carb) didn’t affect food preferences.
6. Brain and Mental Health
Probiotics are bacteria that provide health benefits when consumed. This systematic review of randomized controlled trials concluded that some types of probiotics may help reduce anxiety and depression. However, the evidence is limited.
7. Digestive Health
Silver nanoparticles (SNP) are increasingly being used by the food industry. SNPs have antibacterial activity and increase the shelf-life of processed food products.
This study in mice showed that SNPs didn’t cause any signs of toxicity. However, they disturbed the gut microbiota by reducing bacterial diversity. SNPs likely have similar effects in humans and potentially affect health.
This randomized controlled trial in patients with irritable bowel syndrome (IBS) showed that supplementing with 50,000 IU of vitamin D3 every two weeks for 6 months improved quality of life.
Specifically, it reduced several IBS symptoms, such as abdominal pain, flatulence, distention and rumbling.
8. Kidney and Urinary Health
Renal disease, also known as nephropathy, is a general term referring to impaired kidney function due to disease or injury.
This observational study in African Americans with diabetes showed that a high protein intake was linked to an increased risk of end-stage renal disease.
9. Lung Health
Obesity is associated with a variety of health problems. This observational study suggests that obesity increases the risk of developing asthma.
10. Muscles and Physical Performance
Athletes frequently consume carb supplements before exercise to improve performance.
This systematic review and meta-analysis of randomized controlled trials concluded that carb supplements may improve performance in male cyclists, especially when exercising for more than 90 minutes.
Advanced glycation end-products (AGEs) are a group of compounds that naturally form in your body when sugar reacts with protein. High blood sugar levels promote their formation, but AGEs are also found in some processed food products.
This 6-month randomized controlled study in pre-diabetic people showed that a diet low in AGEs led to an improved blood lipid profile and reduced inflammation.
This systematic review and meta-analysis concluded that plant-based diets are associated with a reduction in obesity-related inflammatory markers.
12. Infections and Immune Health
Periodontitis, or gum disease, is characterized by inflammation in the tissues that surround the teeth. It is caused by a strong immune reaction to the bacteria that live on teeth.
This observational study in South Korean men indicates that drinking a lot of coffee may increase the risk of periodontitis.
13. Longevity and Healthy Aging
Telomeres are sequences of DNA at the ends of DNA strands, which protect them from fusing with neighboring strands. They naturally shorten with age, but oxidative stress may accelerate their shortening, possibly contributing to aging.
This observational study in children showed that exclusive breastfeeding at 4–6 weeks of age was associated with a longer telomere length when the children were 4–5 years of age.
This study in older patients showed that a high score on the Geriatric Nutritional Risk Index (GNRI) was associated with a higher risk of death, a longer hospital stay and lower levels of inflammatory markers.
14. Women’s Health
Premenstrual syndrome (PMS) may occur one or two weeks before women have their periods. The symptoms include anxiety, insomnia, fatigue, headache, emotional sensitivity and mood swings.
This observational study indicates that caffeine intake does not affect PMS.
15. Vitamins, Minerals and Other Nutrients
This observational study found that the milk of obese mothers was much higher in branched-chain amino acids, compared to the milk of lean mothers. The health relevance of this for the child is unclear.