Medical Bulletin 30/ July/ 2024

In a recent study published in journal BMC (Biomed Central), Eating a vegan diet for eight weeks is associated with reductions in biological age estimations based on levels of DNA methylation — a type of chemical modification of DNA (known as an epigenetic modification) that alters gene expression but not DNA itself. Previous research has reported that increased DNA methylation levels are associated with ageing.

Varun Dwaraka, Christopher Gardner and colleagues investigated the molecular effects of a short-term vegan diet by instructing one half of each twin pair to eat an omnivorous diet for eight weeks — including between 170 and 225 grams of meat, one egg, and one and a half servings of dairy each day — and the other half to eat a vegan diet for the same length of time. The sample was 77 percent women (32), and participants were 40 years old on average and had an average body mass index of 26 kilograms per metres squared. For the first four weeks of the study participants ate meals that had been prepared for them and for the second four weeks participants ate meals that they had prepared themselves, after receiving nutrition classes from health educators.

The study investigated the impacts of diet on levels of DNA methylation by analysing blood samples collected from participants at baseline, week four, and week eight of the study. They used DNA methylation levels to infer the biological ages of participants and their organ systems.

The study observed decreases in estimates of biological age — known as epigenetic ageing clocks — in participants who ate a vegan diet but not among those that ate an omnivorous diet. They also observed decreases in the ages of the heart, hormone, liver, and inflammatory and metabolic systems of participants who ate a vegan, but not an omnivorous diet, for eight weeks.

They noted that participants who ate a vegan diet lost two kilograms more on average than those who ate an omnivorous diet due to differences in the calorie contents of meals provided during the initial four weeks of the study. They suggested that these weight loss variations could have contributed to the observed differences in epigenetic age between both groups. Further research is needed to investigate the relationship between dietary composition, weight and ageing, in addition to the long-term effects of vegan diets.

The study concluded that a short term vegan diet has been linked to reduction in biological age estimates, suggesting potential benefits for longevity and health.This dietary approach emphasised on plant-based foods, which are rich in antioxidants, fibre, and essential nutrients. These components can help reduce inflammation, improve metabolic function, and enhance overall well-being. Studies indicate that even brief adherence to a vegan diet can positively impact biomarkers of ageing, potentially lowering the biological age of individuals. This finding underscores the significance of dietary choices in promoting healthy ageing and may encourage further research into plant-based nutrition's long-term effects.

References: Dwaraka, V.B., Aronica, L., Carreras-Gallo, N. et al. Unveiling the epigenetic impact of vegan vs. omnivorous diets on aging: insights from the Twins Nutrition Study (TwiNS). BMC Med 22, 301 (2024). https://doi.org/10.1186/s12916-024-03513-w

A recent study published in a journal CELL, researchers discussed recent advances in molecular nutrition. They focused on pharmaceutical and dietary interventions to manage energy balance and their interactions with the gut microbiome in humans. Further, they explored emerging dietary patterns and the implications of microbiome research on nutrition.

Over the past five decades, molecular nutrition has evolved significantly. Initially centred on micronutrients, the field has shifted towards studying macronutrients and dietary patterns, driven in part by the rising prevalence of obesity. A growing body of evidence highlights the crucial role of the gut microbiome in regulating energy metabolism and dietary responses. This has led to the emergence of precision nutrition, which tailors dietary recommendations based on an individual's genetic and microbiome profiles. Large-scale studies, such as the Personalised Responses to Dietary Composition Trial (PREDICT), have demonstrated the potential of incorporating microbiome data to improve metabolic health outcomes. Nevertheless, further research is needed to validate precision nutrition and integrate it into clinical practice.

This study focuses on recent advancements in diets, energy balance, and the gut microbiome. It intentionally excludes discussions on dietary sugars, plant-based diets, genetically modified organisms (GMOs), and undernutrition. The goal is to highlight the rapid progress and general concepts that can be applied to other areas of nutrition research.

Recent developments in human nutrition are challenging traditional guidelines that emphasise fat restriction, instead embracing diets with moderate to high fat intake. One prominent example is the Mediterranean diet (MD), which is rich in whole grains, legumes, fruits, vegetables, nuts, seeds, and olive oil. This diet has been shown to reduce body weight, body mass index, blood pressure, low-density lipoprotein (LDL) cholesterol, triglycerides, insulin resistance, and inflammation. It also lowers mortality and reduces the risks of type 2 diabetes (T2D) and certain cancers. The beneficial mechanisms of the MD include lipid-lowering effects, protection against oxidative stress, and inhibition of nutrient-sensing pathways. Additionally, the MD positively impacts the gut microbiome by increasing fibre-degrading taxa and promoting beneficial metabolic phenotypes.

It is concluded that diet significantly impacts metabolism and the gut microbiome. Balanced diets like the Mediterranean diet enhance metabolic health and beneficial gut bacteria, while restrictive diets like the ketogenic diet may offer short-term benefits but pose risks of nutrient deficiencies and negative changes in gut microbiome composition.

References: Digesting the complex metabolic effects of diet on the host and microbiome. Carmody, Rachel N. et al., Cell, Volume 187, Issue 15, 3857 – 3876 (2024), DOI: 10.1016/j.cell.2024.06.032, https://www.cell.com/cell/fulltext/S0092-8674(24)00706-2

In a recent study published in Nutrients, researchers explored the caffeine content in various popular coffee servings to assess their safety regarding recommended daily intake limits.

Growing evidence suggests that drinking coffee offers several health benefits, including a reduced risk of type 2 diabetes for regular drinkers. Researchers have also observed an inverse relationship between coffee consumption and cognitive decline in some populations.

Experts recommend consuming three to five cups of coffee daily as part of a healthy diet. However, confusion arises about what constitutes a "cup" due to varying serving sizes and caffeine content. The caffeine content in coffee can vary significantly based on factors such as the type of beans used, brewing methods, and serving sizes.

These variations highlight the need for more specific guidelines on coffee consumption, particularly given the prevalence of chain coffee shops. Coffee contains not only caffeine but also other compounds that influence its health effects.Authorities like the European Food Safety Authority recommend a safe daily caffeine intake of up to 400 mg for adults. They also suggest developing more practical guidelines to help consumers manage their caffeine intake effectively.

The study aimed to analyse the caffeine content in popular coffee servings from both commercial and homemade sources through two separate analyses.The study found significant variation in the caffeine content of different coffee servings, averaging 83 mg per serving, with a range of 13 to 309 mg. Coffees from franchise shops generally contained more than three times the caffeine of homemade coffees.

Among the coffee types studied, Americano had the highest average caffeine content, while the lowest was found in coffee brewed by pouring hot water over ground coffee. Approximately 42% of the coffee samples contained 75–200 mg of caffeine per serving, a range considered beneficial for mental alertness.However, 19% of Americano samples exceeded 200 mg per serving, posing a risk of overconsumption. Consuming three to five servings of high-caffeine coffees like Americano or cappuccino could potentially surpass the recommended safe daily caffeine intake of 400 mg, particularly with high-caffeine servings.

The study revealed significant caffeine content variations across different coffee types, which is critical as caffeine intake estimation can often be inaccurate.

References: Nutrients. doi: 10.3390/nu16152385. https://www.mdpi.com/2072-6643/16/15/2385

A growing number of people are waiting longer to have kids. While there are many reasons people may want to hold back on that decision, about one-third of couples will have difficulties getting pregnant if the female partner is over 35. This is because women's fertility begins declining around that age.

But the researchers of an ongoing clinical trial, published in journal nature portfolio claim rapamycin, a drug commonly used to prevent organ transplants from failing, may be able to extend a woman's fertile years by up to five years.

The early results from a small pilot study suggest potential benefits of rapamycin for fertility treatments, though the findings are not yet peer-reviewed. It will take two years for the clinical trial to conclude before drawing definitive conclusions, but initial results offer some optimism.Previous studies in mice have indicated that rapamycin may positively affect various aspects of ageing, including fertility.

Fertility development can start before birth. While in the womb, female gametes (eggs) surrounded by specialised cells in the ovaries form "primordial follicles." Each follicle contains a single egg that remains dormant until it is recruited for use at puberty.

Numerous follicles die even before birth. This means that every woman is born with all the follicles she will ever have. This is known as the "ovarian reserve". This early-established ovarian reserve can affect a person's ability to become pregnant throughout their reproductive years.

Rapamycin is a bacterial compound that allows cells to survive longer in lab settings.It's commonly used in organ transplant patients to dampen their immune system so that the body doesn't reject the new organ. It's also used to treat certain vascular conditions by slowing down cell growth (such as tumour).A growing body of evidence shows rapamycin may also have benefits when it comes to ageing.

Early results suggest that rapamycin, a common drug, might extend women's fertility by several years. While promising, these findings require further validation through ongoing clinical trials. More research is needed before rapamycin can be considered a viable option for fertility treatment.

References: Mok-Lin E, Ascano M Jr, Serganov A, Rosenwaks Z, Tuschl T, Williams Z. Premature recruitment of oocyte pool and increased mTOR activity in Fmr1 knockout mice and reversal of phenotype with rapamycin. Sci Rep. 2018;8(1):588. Published 2018 Jan 12. doi:10.1038/s41598-017-18598-y.