Medical Bulletin 16/ July/ 2024 - Video

In a recent study published in the journal Nutrition and Metabolism, researchers evaluated the causal effects of dried fruit intake on type 2 diabetes (T2D).

Dried fruits have become popular among people seeking healthier alternatives to snacks. However, concerns regarding its sugar content have emerged regarding T2D. T2D represents a significant public health challenge due to its associations with complications, such as nerve damage, cardiovascular disease, and kidney dysfunction.

Dried fruits contain essential nutrients, such as fiber, vitamins, and minerals, enriching a balanced diet. However, sugars in dried fruits are rapidly released into the bloodstream, causing spikes in postprandial glycemia, which could be challenging for those striving to stabilize glucose levels.

However, there has been a shift in this perspective, with dried fruits now being recognized for their fiber levels, micronutrients, and minimal fat content relative to their fresh counterparts. Animal studies and randomized controlled trials have suggested the potential benefits of dried fruits in cardiovascular diseases.

In the study, researchers explored the potential causal link between dried fruit consumption and type 2 diabetes (T2D) using a method called Mendelian randomization (MR). They used genetic data from a large UK Biobank study involving over 500,000 participants who provided information through questionnaires and measurements. The frequency of dried fruit intake was recorded, and T2D data came from a genetic study with over 61,700 cases and 593,952 controls.

The team identified specific genetic markers (SNPs) associated with dried fruit consumption. They used these markers to analyse the causal effects of dried fruit intake on T2D risk, employing the inverse-variance weighted (IVW) method. Additional methods like the weighted median and MR-Egger were used to support the findings.

The researchers found 43 genetic markers (SNPs) linked to dried fruit intake and selected 36 as instrumental variables, excluding those linked to other factors.

The study revealed a causal relationship between higher dried fruit intake and lower risk of type 2 diabetes (T2D). Specifically, increasing dried fruit intake by one standard deviation was linked to a 61% reduction in T2D risk.

Dried fruits also contain substantial levels of β-carotene, which is protective against T2D development. They also contain diverse flavonoids associated with improved glucose metabolism and insulin sensitivity. The findings highlighted that dried fruit intake was associated with reduced T2D risk.

Reference: Guan J, Liu T, Yang K, Chen H. Dried fruit intake and lower risk of type 2 diabetes: a two-sample Mendelian randomization study. Nutrition & Metabolism, DOI: 10.1186/s12986-024-00813-z, https://nutritionandmetabolism.biomedcentral.com/articles/10.1186/s12986-024-00813-z

A recent study published in the journal Advances In Nutrition reviewed the evidence of the benefits of probiotics for healthy people.

Probiotics are microbes that confer health benefits to the host. Various studies have examined the use of probiotics for diverse conditions for patients and healthy individuals. Clinical trials have also investigated different outcomes in relation to probiotic use. However, a common question remains: should everyone take probiotics? This study reviewed the available evidence to assess the outcomes of probiotic use in healthy people.

The research team assembled experts to explore the evidence. The review primarily focused on healthy individuals and also considered population subgroups. The study explored whether probiotics could prevent infections of the vaginal, respiratory, gastrointestinal (GI), or urinary tract, reduce antibiotic use, or improve cardiovascular risk factors.

Urinary tract infections (UTIs) are the most common bacterial infections, especially in females. Studies have shown that probiotics can help reduce the recurrence of UTIs. For example, a year-long trial found that weekly vaginal suppositories containing Lactobacillus strains reduced UTI recurrence. Another study found that young females taking Lactobacillus crispatus had fewer UTIs compared to a placebo group.

Probiotics also show promise in treating vaginal infections. One trial using Lactobacillus crispatus for bacterial vaginosis (BV) found reduced recurrence rates. Another study indicated that probiotics like Streptococcus thermophilus and Lactobacillus acidophilus could lower BV recurrence compared to placebo.

Probiotics are beneficial in preventing antibiotic-associated diarrhea (AAD). Various studies have reported that probiotics, such as Lactobacillus rhamnosus GG and Saccharomyces boulardii, can reduce AAD risk by 37%.

For diarrhea, probiotics have been shown to reduce incidence. Additionally, probiotics can help lower the risk and incidence of respiratory tract infections (RTIs) in both adults and children.

In terms of cardiovascular disease (CVD) risk factors, probiotics have been found to improve metabolic factors such as cholesterol levels, blood pressure, and body weight. A meta-analysis showed that synbiotics (prebiotics and probiotics) could increase good cholesterol (HDL) and reduce insulin, bad cholesterol (LDL), total cholesterol, triglycerides, systolic blood pressure, body weight, and waist circumference.

In summary, the current efficacy data are insufficient to provide definitive preventive recommendations for probiotics. The field of probiotic research is relatively new, and while there is some evidence of their benefits, more research is needed to confirm their preventive potential.

Reference: Merenstein DJ, Tancredi DJ, Karl JP, et al. Is there evidence to support probiotic use for healthy people? Advances in Nutrition, 2024, OI: 10.1016/j.advnut.2024.100265, https://www.sciencedirect.com/science/article/pii/S2161831324000991

Infections and neurodegenerative diseases cause inflammation in the brain. But for unknown reasons, patients with brain inflammation often develop muscle problems that seem to be independent of the central nervous system.

Now, researchers at Washington University School of Medicine in St. Louis have revealed how brain inflammation releases a specific protein that travels from the brain to the muscles and causes a loss of muscle function.

The study, published in the journal Science Immunology, and conducted in fruit flies and mice, also identified ways to block this process, which could have implications for treating or preventing the muscle wasting sometimes associated with inflammatory diseases, including bacterial infections, Alzheimer's disease and long COVID.

In the study, researchers investigated the effects of brain inflammation on muscle function by modelling three diseases: an E. coli bacterial infection, a SARS-CoV-2 viral infection, and Alzheimer's disease.

They found that brain inflammation caused by these diseases leads to the buildup of reactive oxygen species, which in turn triggers the production of interleukin-6 (IL-6). IL-6 then travels through the bloodstream and reduces energy production in muscle mitochondria. This was observed in both mice and fruit flies.

The study suggested that IL-6 activates the JAK-STAT pathway in muscles, causing decreased mitochondrial function. This pathway can be blocked by existing FDA-approved JAK inhibitors and monoclonal antibodies against IL-6, offering potential treatments for muscle weakness related to brain inflammation.

"We are interested in understanding the very deep muscle fatigue that is associated with some common illnesses. Our study suggests that when we get sick, messenger proteins from the brain travel through the bloodstream and reduce energy levels in skeletal muscle. This is more than a lack of motivation to move because we don't feel well. These processes reduce energy levels in skeletal muscle, decreasing the capacity to move and function normally,” said senior author Aaron Johnson, PhD, an associate professor of developmental biology.

“In the study, flies and mice with COVID-associated proteins in their brains exhibited reduced motor function. Flies had difficulty climbing, while mice ran less and with less efficiency compared to controls. Similar muscle function impairments were observed when the brain was exposed to bacterial-associated proteins and the Alzheimer's protein amyloid beta. The researchers noted that these effects could become chronic, with reduced muscle performance persisting long after the initial infection was cleared..”

Reference: Yang, S., et al. (2024) Infection and chronic disease activate a systemic brain-muscle signaling axis; Washington University School of Medicine; Science Immunology. doi.org/10.1126/sciimmunol.adm7908.