The Heart

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Higher iron levels may protect arteries but raise clot risk

Having higher natural levels of iron could be both good and bad for cardiovascular health, according to new research. On one hand, it may lower the risk of clogged arteries, but on the other hand, it may raise the risk of blood clots related to reduced flow.
illustration of veins
New research reveals the effects of high iron levels on arterial health.

These were the conclusions of a large study that examined the relationship between people's natural iron levels and three measures of cardiovascular disease: carotid artery wall thickness, deep vein thrombosis (DVT), and carotid artery plaque.

Thickening of the vessel wall and the buildup of plaque in the carotid artery are both signs of atherosclerosis.

DVT occurs when a blood clot, or thrombus, forms in a deep vein. DVT typically affects the leg.

The researchers found that having higher levels of iron appears to raise the risk of DVT yet reduce the risk of carotid plaque. There was "no significant effect" on carotid artery wall thickness.

They report their findings in a recent Journal of the American Heart Association study paper.

"These results," write the authors, "are consistent with previous studies that suggest higher iron status has a protective role in atherosclerosis but increases the risk of thrombosis related to stasis of blood."

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Genetic markers of iron status

The study is one of a series that scientists from Imperial College London in the United Kingdom are leading. In these studies, international teams are using genetic data from 500,000 people to explore links between iron levels and more than 900 conditions.

The researchers are using a tool called Mendelian randomization (MR) to investigate links between people's natural iron levels and disease risk.

The authors of the new study suggest that a strength of MR analysis is that it can overcome some of the problems that observational studies face with potential confounders. These can cloud the analysis of likely causes of the observed effects.

"Indeed," they note, "biomarkers of iron status are implicated in other pathologies, including inflammation, liver disease, renal failure, and malignancy, all of which could affect observational associations with thrombotic disease."

By searching DNA data on nearly 49,000 people of European descent, they found genetic markers that correlate with higher natural levels of iron.

The researchers then used the DNA iron level markers to screen other datasets of tens of thousands of people to find links to carotid artery wall thickness, DVT, and carotid artery plaque.

'Contrasting role' of iron status

Atherosclerosis is a major worldwide cause of conditions that affect blood vessels. It can give rise to heart disease, stroke, and peripheral artery disease.

The process of atherosclerosis begins when cholesterol and other fatty materials deposit in artery walls and develop into atheromas. These can eventually rupture and lead to a local clot.

The clot can partially or completely restrict blood flow and cause a stroke or heart attack, depending on which artery it affects.

The researchers suggest that their findings provide evidence of a "contrasting role" of higher natural iron levels on "different thrombotic disease processes."

Speculating on the implications of these findings, lead and corresponding author Dr. Dipender Gill — of the School of Public Health at Imperial College London — suggests that they open new avenues for further studies.

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These could address many unanswered questions, such as how iron affects cholesterol, influences the formation of blood clots, and promotes artery narrowing.

The new study, like others in the series, only investigated people's natural levels of iron using their genetic markers. It did not investigate the effect of taking iron supplements.

Dr. Gill also says that people should speak to their doctor before they start to take or stop taking iron supplements.

"Iron is a crucial mineral in the body and is essential for carrying oxygen around the body," he explains.

"However, getting the right amount of iron in the body is a fine balance — too little can lead to anemia, but too much can lead to a range of problems including liver damage."

Dr. Dipender Gill

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Air pollution may raise atherosclerosis, heart disease death risk

New research examines the link between exposure to air pollution and the risk of coronary artery calcification among Chinese adults.
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A new study provides additional evidence that pollution may affect our cardiovascular health.

Studies have linked air pollution with the risk of developing a range of conditions, from neurological disorders such as Parkinson's disease and Alzheimer's to diabetes and atherosclerosis, which is the hardening of the arteries.

For instance, early last month, Medical News Today reported on a study by researchers at the University at Buffalo School of Public Health and Health Professions in New York, which linked long-term exposure to air pollution with the risk of atherosclerosis in six cities across the United States.

Now, the same lead author, Meng Wang, has carried out similar research in China, making this new study the first to examine pollution and coronary artery calcification among Chinese adults.

Wang and team set out to examine whether "air pollution and proximity to traffic" correlate with coronary artery calcium score, a key marker of atherosclerosis.

Atherosclerosis refers to the buildup of plaque inside the artery walls, which, over time, may lead to serious cardiovascular conditions, such as high blood pressure, heart disease, and heart attacks.

Wang and team published their findings in the journal JAMA Network Open.

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Studying air pollution and artery health

Wang and colleagues examined data on 8,867 Chinese people aged between 25 and 92 years. The participants all had suspected coronary heart disease, and the team recruited them in 2015–2017.

The researchers assessed the coronary artery calcium and coronary heart disease score of each participant and excluded anyone who had had a myocardial infarction, stenting procedure, or coronary artery bypass surgery in the past. They also excluded those for whom the data on risk factors and exposure to pollution were insufficient.

Wang and team estimated the annual levels of pollution at the participants' residences by calculating their nitrogen dioxide, ozone, and fine particulate matter levels using a standard geostatistical prediction model.

In this case, fine particulate matter (PM2.5) describes particles with an aerodynamic diameter smaller than 2.5 micrometers that are very easy to inhale.

Particulate matter, or particle pollution, refers to "a mixture of solid particles and liquid droplets," including "dust, dirt, soot, or smoke," that can be present in the air and that a person cannot see with the naked eye.

In the new study, the researchers also estimated the participants' proximity to traffic, looking at the distance of their residences from nearby roads.

Pollution may raise heart disease death risk

The research revealed that for each nitrogen dioxide increase of 20 micrograms per cubic meter (μg/m3), the risk of a high coronary artery calcium score rose by 24.5%.

Additionally, for each increase of 30 μg/m3 of PM2.5 that the participants had exposure to in their apartments, there was an increase of 27.2% in the coronary artery calcium score.

"This finding should contribute to an understanding of air pollutant effects worldwide, providing both much-needed, locally generated data and supportive evidence to inform the air pollution standard-setting process on a global scale," comments Wang.

"This study may provide evidence that coronary atherosclerosis is a pathological pathway through which air pollution exposure increases risk of death from coronary heart disease."

Meng Wang

The lead author goes on to explain: "Atherosclerosis is a lifelong process. As such, the effects of air pollution exposure on atherosclerosis are likely to be chronic."

"Since more than 40% of all deaths are attributable to cardiovascular disease, the potential contribution of air pollutants to cardiovascular disease in China is very large," says the researcher, suggesting that "the current air pollution standard may need to be reevaluated."

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Top 13 high potassium foods

Potassium is an important nutrient for many body processes. Bananas are a well-known source of potassium, but many other foods contain just as much — if not more — of this nutrient.

Potassium is an electrolyte that helps regulate fluid and blood levels in the body. Many fruits and vegetables are excellent sources of potassium. Meat, milk, yogurt, and nuts are also good sources.

According to the Centers for Disease Control and Prevention (CDC), a diet high in potassium and low in sodium — an electrolyte in table salt and processed foods — can lower blood pressure and reduce the risk of heart disease and stroke.

The adequate intake (AI) of potassium for adults is currently 3,400 milligrams (mg) per day for men and 2,600 mg for women.

According to the Office of Dietary Supplements (ODS), the daily value (DV) of potassium — the daily intake that the Food and Drug Administration (FDA) recommend — will increase to 4,700 mg in January 2020.

Bananas contain 422 mg of potassium per medium fruit. In this article, we take a look at other good sources of potassium according to the ODS and the 2015–2020 Dietary Guidelines for Americans.

1. Dried apricots Dried apricots on a table which are a food high in potassium
Dried apricots are a good source of iron, antioxidants, and potassium.

Several dried fruits are high in potassium. Apricots are a bright orange fruit that people may eat either fresh or dried.

Half a cup of dried apricots contains 1,101 mg of potassium. These fruits also provide other key nutrients, such as iron and antioxidants.

When purchasing dried apricots, a person should look for those that contain no added sugar. They can eat dried apricots as a snack or add them to salads or main meals.

2. Potatoes Potatoes are an excellent source of potassium. Baked potatoes with the skin still on are the best option, as much of a potato's potassium is in the skin. One medium baked potato with skin contains 941 mg of potassium. By eating a baked potato with salt-free seasoning, a person can avoid extra sodium. French fries are usually lacking in nutrients and contain added fat from oil and the frying process, making them a less healthful option. Fries also typically contain high amounts of sodium, which can counteract the benefits of potassium. 3. Leafy greens Leafy greens are some of the most nutritious foods available. One study found that eating a serving per day of leafy green vegetables may help slow age-related cognitive decline. Leafy green vegetables are low in calories and contain many vitamins and minerals. Most also provide a good amount of potassium. For instance: A cup of cooked Swiss chard contains 962 mg of potassium. A cup of cooked amaranth leaves contains 846 mg. A cup of cooked spinach contains up to 838 mg. Thank you for supporting Medical News Today 4. Lentils cooked red lentils in a wooden bowl on table with garlic and chilies
Lentils contain potassium, fiber, and protein. Lentils are a small, round legume. They contain plenty of fiber and are also rich in protein. One cup of cooked lentils contains 731 mg of potassium. Lentils make a good addition to soups or stews. People looking for a quicker option can use canned rather than dried lentils. However, it is important to rinse canned lentils well before use to remove any sodium. 5. Prunes and prune juice Prunes are dried plums. Due to their high fiber content and other chemical properties, many people use prunes or prune juice to help relieve constipation. Juice companies usually make prune juice by adding water back into the prunes, cooking them, and then filtering out the solids. There are 707 mg of potassium in one cup of canned prune juice, while half a cup of dried prunes contains 699 mg. 6. Tomato puree or juice Fresh tomatoes offer several health benefits. To get more potassium, though, it is best to use concentrated tomato products, such as tomato puree or tomato juice. Half a cup of tomato puree contains 549 mg of potassium, and a cup of tomato juice contains 527 mg. Fresh tomatoes also contain potassium, with one medium raw tomato containing 292 mg. People often use tomato puree in cooking, for example, adding it to pasta sauces. Canned or bottled tomato juice is also suitable to use in many recipes, or people can drink it. 7. Certain fruit and vegetable juices Some varieties of juice contain high amounts of potassium. However, many health organizations recommend that people avoid juices with added sugar. Whole fruit contains more fiber than juice and often more nutrients as well. Still, 100% juice can be part of a healthy diet in limited amounts, according to the American Heart Association and the Dietary Guidelines for Americans. The following juices are high in potassium, containing the following amounts per cup: carrot juice (canned): 689 mg passion fruit juice: 687 mg pomegranate juice: 533 mg orange juice (fresh): 496 mg vegetable juice (canned): 468 mg tangerine juice (fresh): 440 mg 8. Raisins Raisins are another type of dried fruit that is high in potassium. Raisins are a popular snack food. Half a cup of raisins contains 618 mg of potassium. For the most healthful type, opt for raisins that contain only dried grapes with no added sugar, coatings, or other ingredients. 9. Beans Beans come in many sizes, shapes, and colors. Most contain a high amount of fiber, some protein, and a good dose of potassium. Kidney beans are red, kidney-shaped legumes that people often use in soups, chili, or as a side dish of baked beans. A cup of canned kidney beans contains 607 mg of potassium. Many other beans are also high in potassium. The amounts per half cup serving are as follows: adzuki beans: 612 mg white (cannellini) beans: 595 mg lima beans: 478 mg great northern beans: 460 mg black beans: 401 mg canned refried beans: 380 mg navy beans: 354 mg 10. Milk and yogurt People typically think of dairy products, such as milk and yogurt, as being rich sources of calcium. However, some dairy products are also a good way to add more potassium to the diet. Studies suggest that in the United States, milk is the top source of potassium among adults. A cup of 1% milk contains 366 mg. Many people also get their potassium from tea and coffee. An 8-ounce (oz) cup of brewed black coffee contains 116 mg of potassium, which would classify it as a low potassium food, but adding creamers and milk raises the potassium content considerably. Other dairy products also contain potassium. For instance, one cup of plain nonfat yogurt contains up to 579 mg. 11. Sweet potatoes sweet potato wedges
Sweet potatoes are rich in potassium. Sweet potatoes have orange flesh and a sweeter flavor than white potatoes. Their orange color means that they provide more beta carotene than other potatoes, but they also contain potassium. A baked sweet potato with the skin still on contains 542 mg of potassium. For the most healthful option, a person should eat baked or microwaved sweet potatoes without added sugar. It is also best to avoid canned sweet potatoes that the manufacturers have packaged in syrup. Thank you for supporting Medical News Today 12. Seafood Fish and shellfish contain heart-healthy omega-3 fats. The American Heart Association recommend eating fish (particularly fatty fish) at least twice a week. Certain types of seafood are also good sources of potassium. Wild Atlantic salmon and clams lead the way with 534 mg of potassium per 3-oz serving. The same serving size of other types of seafood high in potassium offers: mackerel: up to 474 mg halibut: 449 mg snapper: 444 mg rainbow trout: up to 383 mg 13. Avocado Avocado is a buttery fruit that contains a variety of nutrients, including heart-healthy monounsaturated fat and vitamins C, E, and K. Avocados also contain nearly 5 grams of fiber in half a cup. Avocados are a good source of potassium, providing 364 mg in a half-cup serving. People can eat avocados raw in salads, as dips, or on toast. They also work well in cooked meals, such as pasta dishes. What about potassium supplements? Some people may wonder about using supplements to boost their potassium intake. Only a few studies have investigated the effects of potassium supplements, and some suggest that the body can absorb potassium as well from supplements as it can from food. However, the ODS say that in many dietary supplements, manufacturers limit the amount of potassium to 99 mg — only about 3% of a person's DV — due to safety concerns about drugs that contain potassium. People with kidney problems should be cautious about consuming too much potassium, as this can lead to hyperkalemia, or high levels of potassium in the blood. Potassium from food, however, does not cause harm in healthy people who have normal kidney function. When the kidneys are functioning well, any excess potassium from food dissolves in water and leaves the body in the urine. Summary If a person eats a diet rich in vegetables, fruits, and legumes, they should get enough potassium in their diet. It is beneficial to balance this by eating low amounts of high sodium foods, such as processed foods and fast food. This dietary approach can not only help keep potassium at a healthy level, but it may help people obtain a variety of other vitamins and nutrients that occur in whole foods and contribute to better health.
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Switching off this enzyme reversed prediabetes in mice

Targeting the body's ceramide chemistry in a subtle way could lead to the development of safe new treatments for type 2 diabetes, heart disease, and other metabolic conditions.
image of dna code on screen in foreground, scientists working in the background
Scientists have reversed prediabetes by switching off a certain enzyme.

This was the suggestion that scientists made after finding that they could reverse prediabetes in mice with obesity by silencing an enzyme responsible for the final step of ceramide production.

Deactivating the enzyme, called dihydroceramide desaturase 1 (DES1), lowered levels of ceramide in the body, they note in a recent Science paper about their work.

Switching off DES1 also prevented mice on a high fat diet from developing fatty liver and insulin resistance. These two conditions are prime risk factors for heart disease and diabetes.

DES1 controls the conversion of dihydroceramide into ceramide with a small chemical shift of two hydrogen atoms. This subtle alteration effectively inserts a "double bond into the backbone" of the lipid molecule.

Previous investigations had already suggested that reducing ceramide levels could potentially reverse metabolic disease and diabetes. However, the methods that they used would result in severe side effects.

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'Ceramides as the next cholesterol'

The new study takes the research in a more promising therapeutic direction. It suggests that it could be possible to reduce ceramide levels in a safe way with a small, well timed tweak to the process of ceramide production.

"Our work," says co-senior study author Prof. Scott A. Summers, department chair of Nutrition and Integrative Physiology at the University of Utah in Salt Lake City, "shows that ceramides have an influential role in metabolic health."

"We're thinking of ceramides as the next cholesterol," he adds.

Scientists are still finding out how lowering the ceramides affects the body. However, there is evidence, Prof. Summers argues, of a link between ceramides and metabolic disease.

He says that some doctors are already carrying out tests of ceramide levels as a way to assess people's risk for heart disease.

"Ceramides contribute to the lipotoxicity that underlies diabetes, hepatic steatosis [fatty liver], and heart disease," note the authors of the new study.

If ceramides can be a cause of disease, what purpose do they serve in the body? The researchers investigated this question by assessing the impact of ceramide on metabolism.

Ceramide pros and cons

In a 2013 study into DES1 and ceramides, Prof. Summers and his co-authors discussed how obesity could increase metabolic disease risk, and how ceramides contribute.

The theory is that in people with obesity, the body's tissues receive an abundance of lipids that they cannot store, and this leads to a buildup of "fat-derived molecules that impair tissue function."

Prof. Summers and his colleagues discovered that ceramides set off a number of processes that increase fat storage in cells. In addition, they disrupt the ability of cells to get energy from sugar, or glucose.

The lipids also slow down the processing of fatty acids. They do this in two ways: by getting the liver to store more fatty acids, and by reducing fat burning in tissues.

Ceramides also have other functions. One of these is to strengthen cell walls.

Prof. Summers therefore suggests that because increasing fat storage raises ceramide levels, it would seem that ceramides have a role in protecting cells from rupturing during times of plenty, when the body increases its fat stores.

However, in the case of obesity, ceramide appears to take on the role of a toxic lipid.

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Obese mice had improved metabolic health

In the recent study, the researchers lowered ceramide levels in mice by shutting off the last step of ceramide synthesis. To accomplish this, they genetically engineered mice in which they could switch off the gene for DES1 in adult animals.

They developed two ways of switching off DES1: globally and selectively. In the global approach, they silenced DES1 in the whole body. In the selective approach, they switched off the enzyme in selective locations, such as in the liver or fat cells.

When they switched off DES1 to lower ceramides in extremely obese mice with insulin resistance and fatty liver, they found that either approach worked. The animals' metabolic health improved, even though they remained obese.

Their livers got rid of fat, and their insulin and glucose responses were as sharp as those of healthy, lean mice. After 2 months of observation, the animals remained in good health.

Prof. Summers explains that although the mice did not shed any weight, their bodies had changed the way that they processed nutrients.

In another set of experiments, the team found that reducing ceramide levels before placing the mice on high fat diets stopped the animals from gaining weight and developing insulin resistance.

"We have identified a potential therapeutic strategy that is remarkably effective and underscores how complex biological systems can be deeply affected by a subtle change in chemistry."

Prof. Scott A. Summers

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These diets and supplements may not really protect the heart

Doctors often recommend certain dietary interventions — such as following a Mediterranean-type diet or cutting salt intake — in the interest of protecting heart health. On top of this, many individuals believe that dietary supplements will help them stay healthy.
image of healthy foods vs supplements
Can supplements and dietary interventions protect the heart? Not according to a new meta-analysis.

Common knowledge has it that diet and lifestyle play an important role in supporting a person's physical health and overall well-being.

That is why doctors may advise their patients to modify their diets and lifestyle habits by making them more conducive to good health.

In particular, dietary interventions can allegedly help individuals safeguard their cardiovascular health, preventing heart disease and events such as strokes.

Dietary guidelines for people in the United States advise that people adhere to healthful diets, such as a vegetarian diet or the Mediterranean diet, which is rich in vegetables, legumes, and lean meat.

On a related note, many individuals believe that taking dietary supplements can enhance different aspects of their health, including heart health, although recent studies have contradicted this assumption.

Now, a meta-analysis by researchers from different collaborating institutions — including The Johns Hopkins School of Medicine in Baltimore, MD, West Virginia University in Morgantown, and Mayo Clinic in Rochester, MN — suggests that many interventions and even more supplements may have no protective effect for the heart, and some may even harm cardiovascular health.

The review — the first author of which is Dr. Safi Khan from West Virginia University — appears in Annals of Internal Medicine.

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In their research, Dr. Khan and team analyzed the data from 277 randomized controlled trials that had involved almost 1 million participants between them. They looked at the effects of 16 nutritional supplements and eight dietary interventions on cardiovascular health and mortality.

The supplements that they took into consideration were: selenium, multivitamins, iron, folic acid, calcium, calcium plus vitamin D, beta carotene, antioxidants, omega-3 long-chain polyunsaturated fatty acids, and vitamins A, B complex, B-3, B-6, C, D, and E.

The dietary interventions included: modified dietary fat, reduced salt (in people with normal and high blood pressure), reduced saturated fat, Mediterranean diet, reduced dietary fat, higher intake of omega-6 polyunsaturated fatty acids, and higher intake of omega-3 alpha-linolenic acid.

Dr. Khan and colleagues did find that some of these interventions had a positive effect. For instance, eating less salt may reduce the risk of premature death in people with a normal blood pressure, although only with moderate certainty.

Moreover, they concluded that omega-3 long-chain polyunsaturated fatty acids protected against heart attacks and coronary heart disease and that there was an association between folic acid intake and a slightly lower risk of stroke, but all with only low certainty.

At the same time, however, other supplements and interventions seemed to either have no effect or be downright harmful.

The researchers found that taking multivitamins, selenium, vitamin A, vitamin B-6, vitamin C, vitamin D, vitamin E, calcium, folic acid, and iron did not significantly protect against cardiovascular problems and early death. They also noted that following a Mediterranean diet, reducing saturated fat intake, modifying fat intake, reducing dietary fat intake, and increasing the quantity of dietary omega-3 and omega-6 were not beneficial.

In fact, people who took calcium and vitamin D supplements together actually had a higher risk of experiencing a stroke, although only with moderate certainty.

However, in their paper, the investigators admit that "these findings are limited by suboptimal quality of the evidence." They are referring to the fact that, due to the different methodologies of the studies that they assessed, they "could not analyze interventions according to important subgroups, such as sex, body mass index [BMI], lipid values, blood pressure thresholds, diabetes, and history of [cardiovascular disease]."

Yet, they argue that their current review paves the way to better care and stronger research into the helpfulness and value of different dietary interventions:

"This study can help those who create professional cardiovascular and dietary guidelines modify their recommendations, provide the evidence base for clinicians to discuss dietary supplements with their patients, and guide new studies to fulfill the evidence gap."

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The authors of the accompanying editorial, doctors Amitabh Pandey and Eric Topol, both from the Scripps Research Translational Institute in La Jolla, CA, also emphasize that the quality of the data in many studies assessing the effects of dietary interventions and supplements on heart health can be questionable.

"[D]ifferences in geography, dose, and preparation — most studies rely on food diaries, which are based on a person's memory of what they consumed — raise questions about the veracity of the data," they write.

"Perhaps, however, the biggest difference that needs to be considered in the future is the individual," they add, advising that future research should pay more attention to the differences among participants.

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