Day: August 31, 2023

Categories : Cardiovascular Disease Diet and NutritionTags :

Could a Simple Dietary Change Increase Platelet Counts?

On By ModernMedia
Scanning electron micrograph of red blood cells, T cells (orange) and platelets (green). Source: Wikimedia CC0

Aside from transfusions, there currently is no way to boost people’s platelet counts, which can drop for reasons such as chemotherapy, leaving them at risk for uncontrolled bleeding. But new research published in Nature Cardiovascular Research suggests that there could be a simple alternative: a dietary change in type of fat intake could raise platelet counts in people with low levels.

A study led by Kellie Machlus, PhD, and Maria Barrachina, PhD at Boston Children’s Hospital found that they could raise platelet counts in mice by feeding them polyunsaturated fatty acids (PUFAs) like those found in the Mediterranean diet. In contrast, mice fed a diet high in saturated fatty acids had decreased platelet counts.

“We were honestly surprised at how profound the effects were,” says Machlus, whose lab focuses on studying platelets and their precursor cells, megakaryocytes, and ways to get the body to increase platelet production.

But equally interesting is the apparent reason for the dietary effect.

“What brought me to the idea of diet is that megakaryocytes make these long extensions from their membrane when they form platelets,” Machlus says. “We thought the membrane must have an unusual composition to make it so fluid.”

A fluid megakaryocyte membrane

No one had studied megakaryocyte membranes before, perhaps because megakaryocytes are in the bone marrow and hard to access. Machlus, Barrachina, and their colleagues decided to comprehensively assess the membranes’ fat content with lipidomics.

“We found that PUFAs are enriched in megakaryocytes, especially right before they begin making platelets,” says Machlus. “We think they provide the fluidity necessary for the membrane to move and reshape.”

In culture, the megakaryocytes with higher amounts of PUFAs in their membrane made more platelets. When the cells were instead supplied with saturated fats as their lipid source, platelet production declined. The same thing happened when the team added compounds to inhibit uptake of PUFAs from the blood.

The researchers also identified one of the receptors on megakaryocytes that’s responsible for taking up PUFAs from blood: CD36. When they deleted the gene for CD36 in their mouse model, the animals had low platelet counts.

Serendipitously, the researchers were able to connect the dots to humans. Through a colleague in the U.K., they identified a family in which several members had a mutation in the CD36 gene. Those affected had low platelet counts and, in the mother’s case, bleeding episodes.

An olive oil intervention?

Intrigued by their findings, Barrachina hopes to extend the study by collaborating with a team in her native Spain. The team is studying dietary interventions for cardiovascular disease, including the Mediterranean diet.

“We want to look at platelets from these patients,” she says. She thinks that platelets with more saturated fatty acids in their membranes might be in a more activated state that could lead them to aggregate and form blood clots.

While Machlus thinks it may be worth encouraging patients with thrombocytopenia to consume more olive oil to increase PUFA levels, she recognises that a drug treatment may be more practical.

“Our next steps are to find out the enzymes that create PUFAs,” she says. “Maybe we can target them to make more platelets.”

Source: Boston Children’s Hospital

Categories : Gender Immune SystemTags :

Male and Female Immune Systems are Trained Differently

On By ModernMedia
Scanning electron micrograph of a B cell. Credit: NIH

When the immune system is compromised due to various conditions and medicines, patients can experience opportunistic infection. Now, researchers reporting in Cell Reports have uncovered a sex-based variance in the trained immune memory response to infection in mice that might translate to humans.

The researchers, from the University of Missouri School of Medicine, found that female mice were more vulnerable to opportunistic infection from a bacterial pathogen to which they had previously been exposed when progesterone levels were naturally elevated as part of their reproductive cycle.

“Differences in immune response in males and females have been observed before. For instance, males had increased morbidity and severity of COVID-19 from SARS-CoV-2 infections,” said Dr Adam Schrum, associate professor in the Department of Molecular Microbiology and Immunology. “But females are known to suffer other infections worse than males. Our research found that female mice were far more vulnerable to opportunistic bacterial infection than male mice because of a sex-based difference in their trained immunity.”

To understand why the immune systems of female and male mice responded differently to a bacterial pathogen, the researchers examined whether the reproductive cycle affected immune training. They found that elevated progesterone levels correlated with lower trained immune responses. To test this more fully, the researchers gave the female mice progesterone blockers and found that their trained immune response was subsequently enhanced.

“The female mice had significantly restored trained immune response when progesterone was blocked, reaching comparable levels to those of male mice,” said Schrum. “Sex hormone-based modulation of immune function needs more study to be fully understood, but as a first step we can conclude that immune training is influenced by a progesterone-dependent mechanism that results in a sex bias in mice.”

In addition to further study to understand how and why progesterone specifically influences trained immune responses in mice, the researchers pointed out that because mice have shorter estrous cycles than the human menstrual cycle, further research is needed to understand how sex hormones might affect human immune training.

Source: University of Missouri-Columbia

Categories : Cardiovascular Disease ExerciseTags :

Even Moderate Physical Fitness Protects Against Atrial Fibrillation and Stroke

On By ModernMedia
Photo by Barbara Olsen on Pexels

A study in more than 15 000 people has found that even moderate physical fitness is linked with a lower likelihood of developing atrial fibrillation and stroke. Progressively higher levels of fitness also reduced the risk of cardiovascular events. The research is presented at ESC Congress 2023.

Atrial fibrillation is the most common heart rhythm disorder, and patients with the condition have a five-fold higher risk of stroke than their peers. This study examined whether fitness was related to the likelihood of developing atrial fibrillation.

The study included 15 450 individuals without atrial fibrillation who were referred for a treadmill test between 2003 and 2012. The average age was 55 years and 59% were men. Fitness was assessed using the Bruce protocol, where participants are asked to walk faster and at a steeper grade in successive three-minute stages. Fitness was calculated according to the rate of energy expenditure the participants achieved, which was expressed in metabolic equivalents (METs).

Participants were followed for new-onset atrial fibrillation, stroke, myocardial infarction and death. The researchers analysed the associations between fitness and atrial fibrillation, stroke and major adverse cardiovascular events (MACE; a composite of stroke, myocardial infarction and death) after adjusting for factors that could influence the relationships including age, sex, cholesterol level, kidney function, prior stroke, hypertension and medications.

During a median of 137 months, 515 participants (3.3%) developed atrial fibrillation. Each one MET increase on the treadmill test was associated with an 8% lower risk of atrial fibrillation, 12% lower risk of stroke and 14% lower risk of MACE.

Participants were divided into three fitness levels according to METs achieved during the treadmill test: low (less than 8.57 METs), medium (8.57 to 10.72) and high (more than 10.72). The probability of remaining free from atrial fibrillation over a five-year period was 97.1%, 98.4% and 98.4% in the low, medium and high fitness groups, respectively.

Study author Dr Shih-Hsien Sung of the National Yang Ming Chiao Tung University, Taipei, Taiwan said: “This was a large study with an objective measurement of fitness and more than 11 years of follow up. The findings indicate that keeping fit may help prevent atrial fibrillation and stroke.”

Source: European Society of Cardiology

Categories : Diet and NutritionTags :

‘Berry’ Good for You? Adding a Banana Reduces Flavanol Levels in Smoothies

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Photo by Denis Tuksar on Unsplash

Smoothies can be a tasty and convenient way to get the important fruits and vegetables needed for a healthy diet. But is a banana and blueberry smoothie the best combo? Researchers at the University of California, Davis, suggest that blending certain ingredients in smoothies can influence whether your body is getting a nutritional boost.

The study, published today in the journal Food and Function, used smoothies to test how various levels of polyphenol oxidase (PPO), an enzyme in many fruits and vegetables, affects the levels of flavanols in food to be absorbed by the body. Flavanols are a group of bioactive compounds that are good for your heart and cognitive health and are naturally found in apples, pears, blueberries, blackberries, grapes and cocoa – common smoothie ingredients.

“We sought to understand, on a very practical level, how a common food and food preparation like a banana-based smoothie could affect the availability of flavanols to be absorbed after intake,” said lead author Javier Ottaviani, director of the Core Laboratory of Mars Edge, which is part of Mars, Inc., and an adjunct researcher with the UC Davis Department of Nutrition. Mars Inc. provided the grant for this study as part of its research into flavonols in cocoa.

When peeled or sliced, PPO causes banana or apple to turn brown, The browning occurs when food with PPO is exposed to air, cut or bruised. The researchers wanted to know whether consuming freshly prepared smoothies made with different PPO-containing fruits impacted the amount of flavanols available to the body.

Bananas versus berries

The researchers had participants drink a smoothie made with banana, which has naturally high PPO activity, and a smoothie made with mixed berries, which have naturally low PPO activity. Participants also took a flavanol capsule as a control. Blood and urine samples were analysed to measure how much flavanols were present in the body after ingesting the smoothie samples and capsule. The researchers found that those who drank the banana smoothie had 84% lower levels of flavanols in their body compared to the control.

“We were really surprised to see how quickly adding a single banana decreased the level of flavanols in the smoothie and the levels of flavanol absorbed in the body,” Ottaviani said. “This highlights how food preparation and combinations can affect the absorption of dietary compounds in foods.”

Last year, the Academy of Nutrition and Dietetics issued a dietary recommendation, advising people to consume 400 to 600 milligrams of flavanols daily for cardiometabolic health. Ottaviani said for people who are trying to consume those flavanols, they should consider preparing smoothies by combining flavanol-rich fruits like berries with other ingredients that also have a low PPO activity like pineapple, oranges, mango or yogurt.

He also said bananas remain a great fruit to be eaten or consumed in smoothies. For those who want to consume smoothies with bananas, or other high PPO activity fruits and vegetables such as beet greens, the suggestion is to not combine them with flavanol-rich fruits such as berries, grapes and cocoa.

The findings of this study could spur future research into how other foods are prepared and the effects on flavanols, for example, Ottaviani said tea is a major dietary source of flavanols and depending on how it is prepared, a different amount of flavanols would be available for absorption.

“This is certainly an area that deserves more attention in the field of polyphenols and bioactive compounds in general,” said Ottaviani.

Jodi Ensunsa, Reedmond Fong, Jennifer Kimball and Alan Crozier, all affiliated with the UC Davis Department of Nutrition and researchers affiliated with the UC Davis Department of Internal Medicine, University of Reading, King Saud University and Mars, Inc. contributed to the research.

The study was funded by a research grant from Mars, Inc., which collaborates with researchers to study potential benefits of cocoa flavanols for human health.

Source: University of California – Davis

Categories : Ageing GenderTags :

Women Who Reach Their 90s Tend to Have Maintained Stable Weight

On By ModernMedia
Photo by Loren Joseph on Unsplash

Reaching the age of 90, 95 or 100, known as exceptional longevity, was more likely for women who maintained their body weight after age 60, according to a multi-institutional study led by University of California San Diego. Older women who sustained a stable weight were 1.2 to 2 times more likely to achieve longevity compared to those who lost 5% of their weight or more.

In this study published in the Journal of Gerontology: Medical Sciences, researchers investigated the link between weight changes later in life with exceptional longevity among 54 437 women who enrolled in the Women’s Health Initiative, a prospective study investigating causes of chronic diseases among postmenopausal women. Throughout the follow up period, 30 647 (56%) of the participants survived to the age of 90 or beyond.

Women who lost at least 5% weight were less likely to achieve longevity compared to those who achieved stable weight. For example, women who unintentionally lost weight were 51% less likely to survive to the age of 90. However, gaining 5% or more weight, compared to stable weight, was not associated with exceptional longevity.

“It is very common for older women in the United States to experience overweight or obesity with a body mass index range of 25 to 35. Our findings support stable weight as a goal for longevity in older women,” said first author Aladdin H. Shadyab, PhD, MPH, associate professor at UC San Diego.

“If aging women find themselves losing weight when they are not trying to lose weight, this could be a warning sign of ill health and a predictor of decreased longevity.”

The findings suggest that general recommendations for weight loss in older women may not help them live longer. Nevertheless, the authors caution that women should heed medical advice if moderate weight loss is recommended to improve their health or quality of life.

The data adds to research connecting weight change and mortality and is notably the first large study to examine weight change later in life and its relation to exceptional longevity.

Source: University of California – San Diego