This is our weekly selection of recently published studies and reviews in nutrition. Here are some of the most in
teresting findings this week:
- Pro-inflammatory diets are associated with an increased risk of weight gain and obesity.
- Inadequate water intake impairs blood sugar control.
- A low-FODMAP diet may not benefit people with inflammatory bowel disease.
New Research From Around the World
Lots of recent 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
- Brain and Mental Health
- Digestive Health
- Bone Health
- Muscles and Physical Performance
- Antioxidants and Oxidative Stress
1. Obesity and Weight Loss
The Dietary Inflammatory Index (DII) rates the inflammatory potential of a diet. Some foods are pro-inflammatory, whereas others are anti-inflammatory or neutral.
This observational study followed 7,027 university graduates for approximately eight years. It found that pro-inflammatory diets were associated with a higher yearly weight gain and an increased risk of overweight or obesity, even when taking weight loss supplements like garcinia cambogia.
2. Blood Sugar Control and Diabetes
This meta-analysis of observational studies concluded that diets high in refined grains, sugar-sweetened soft drinks, high-fat dairy, fried foods and/or processed meat were significantly associated with an increased risk of type 2 diabetes (T2D).
In contrast, dietary patterns characterized by vegetables, fruits, legumes, fish and poultry were linked with a reduced risk of T2D.
This crossover study in 18 Japanese adults with type 2 diabetes found that eating glutinous brown rice twice a day for two months improved blood sugar control and reduced hemoglobin levels, compared to white rice.
Previous studies show that inadequate water intake is associated with poor blood sugar control.
This observational study in nine diabetic men confirmed previous findings. It found that drinking little water for three days impaired their ability to keep blood sugar levels in check after eating sugar.
3. Heart Health
This observational study followed 2,369 Iranian adults for about seven years. It found that protein intake had no significant effect on the risk of heart disease. However, the amino acid composition of dietary proteins may play a role.
Specifically, a high intake of glycine, cysteine, arginine, tryptophan and sulphur-containing amino acids was linked to a reduced risk of heart disease. In contrast, a high intake of glutamic acid and proline increased the risk of heart disease.
This prospective observational study in 136,739 South Korean children and adolescents showed that a higher meat intake was associated with lower body mass index and blood pressure.
Peripheral artery disease (PAD) is when arteries (other than those that supply the heart or brain with blood) start to narrow. PAD may restrict blood supply to the legs, arms or other body parts.
This study in 3,696,778 US adults found that a high intake of fruits and vegetables was linked to a lower risk of PAD. Eating three or more servings daily was linked to an 18% lower risk of PAD, compared to eating fruits and vegetables less than monthly.
This meta-analysis of prospective observational studies including a total of 784,550 participants concluded that the intake of vitamin B6 is not significantly associated with the risk of colorectal cancer.
However, a dose-response analysis, which included a few eligible studies, showed that for each 5 mg increase in vitamin B6 intake, the risk of colorectal cancer decreased by 17%.
5. Brain and Mental Health
This observational study followed 2,400 Japanese adults aged 40–79 for up to 19 years. It found that a high intake of protein was associated with a reduced risk of stroke.
Vegetable protein appeared to be especially protective. A high vegetable protein intake was linked to a 40% reduced risk of stroke, compared to those with the lowest intakes.
6. Digestive Health
FODMAPs are a category of carbs that are poorly absorbed. They may cause digestive discomfort in some people, especially those with irritable bowel syndrome or inflammatory bowel disease (IBD).
This meta-analysis of controlled studies including a total of 319 patients concluded that there is no evidence that low-FODMAP diets benefit people with IBD.
7. Bone Health
This observational study in 1,039 Danish people showed that vitamin D status in newborn infants is not associated with the risk of fractures in childhood.
8. Muscles and Physical Performance
Even mealtime distribution of protein intake is associated with greater muscle strength, but not with 3-y physical function decline, in free-living older adults: the Quebec longitudinal study on Nutrition as a Determinant of Successful Aging (NuAge study).
Eating adequate amounts of protein with every meal may be important in the maintenance of muscle mass among older people.
This observational study in 1,741 older, Canadian adults found that eating sufficient protein with all meals is associated with greater muscle strength, compared to eating most of their daily protein in one meal.
The Mediterranean diet is associated with various health benefits. It is characterized by a high intake of whole grains, vegetables, fruits, nuts and fish, as well as a lower intake of red meat.
This observational study in 3,289 Chinese adults aged 40–75 found that a diet that scored high on the Alternate Mediterranean diet score was associated with higher muscle mass, especially among men and younger participants.
Mobility, or a person’s ability to move, is an important aspect of physical function. Impaired mobility is an serious problem for many older people.
This observational study followed 1,630 older Spanish people for around 3.5 years. It found that a higher intake of vitamin B6, as well as foods rich in vitamin B6, such as fish and fruits, was associated with a reduced risk of impaired mobility.
This two-week crossover study in 14 healthy men compared the effects of eating 400 grams of probiotic yogurt (PY) or acidified milk (AM) every day on inflammatory markers. The study detected no significant differences between the two.
However, both PY and AM reduced the inflammatory response to a high-fat meal, compared to responses at the start of the study. They also appeared to cause beneficial changes in the gut microbiota.
Quercetin is one of the most common antioxidant flavonoids found in plant foods. It is also sold as a supplement. Previous studies suggest it may have anti-inflammatory effects.
This meta-analysis of controlled studies concluded that quercetin may reduce the levels of C-reactive protein (CRP), a common inflammatory marker, especially when taken in doses exceeding 500 mg per day and among patients who are high in CRP.
10. Antioxidants and Oxidative Stress
Oxidative stress (OS) is a condition characterized by low levels of antioxidants, relative to oxidants. It has been linked to various chronic diseases and inflammation.
This controlled study in 48 patients with diabetic kidney disease showed that eating 200 ml of probiotic soy milk every day for two months reduced several markers of oxidative stress, compared to normal soy milk.
The cause of migraines is unknown. Scientists have hypothesized that increased intestinal permeability (IP), which may allow toxins to “leak” into the bloodstream, may be to blame.
This controlled study in 63 patients showed that taking multispecies probiotic supplements daily for three months did not reduce the risk or severity of migraines, compared to a placebo. Also, markers of IP or inflammation did not improve.