When it comes to describing what an antioxidant is, it’s all in the name: Antioxidants counter oxidants.

And that’s a good thing. Oxidants can damage the structure and function of the chemicals in your body critical to life – like the proteins and lipids within your cells, and your DNA, which stores genetic information. A special class of oxidants, free radicals, are even more reactive and dangerous.

As an assistant professor of nutrition, I’ve studied the long-standing research showing how the imbalances in antioxidants and oxidants lead to oxidative stress, which is linked to cancer, diabetes, cardiovascular disease and dementia and Alzheimer’s disease. In fact, a primary cause of aging is the damage accumulated across of a lifetime of oxidative stress.

Simply put: To help prevent oxidative stress, people need to eat foods with antioxidants and limit their exposure to oxidants, particularly free radicals.

The research: Food, not supplements

There’s no way for any of us to avoid some oxidative stress. Just metabolism – the processes in your body that keep you alive, such as breathing, digestion and maintaining body temperature – are a source of oxidants and free radicals. Inflammation, pollution and radiation are other sources.

As a result, everyone needs antioxidants. There are many different types: enzymes, minerals, vitamins and phytochemicals.

Two types of phytochemicals deserve special mention: carotenoids and flavonoids. Carotenoids are pigments, with the colors yellow, orange and red; they contain the antioxidants beta-carotene, lycopene and lutein. Some flavonoids, called anthocyanins, are pigments that give foods a blue, red or purple color.

Although your body produces some of these antioxidants, you can get them from the foods you eat, and they’re better for you than supplements.

In fact, researchers found that antioxidant supplements did not reduce deaths, and some supplements in excessive amounts contribute to oxidative stress, and may even increase the risk of dying.

It should be pointed out that in most of these studies, only one or two antioxidants were given, and often in amounts far greater than the recommended daily value. One study, for example, gave participants only vitamin A, and at an amount more than 60 times an adult’s recommended intake.

Foods rich in antioxidants

In contrast, increased antioxidant intake from whole foods is related to decreased risk of death. And although antioxidant supplementation didn’t reduce cancer rates in smokers, the antioxidants in whole foods did.

But measuring antioxidants in foods is complicated. Extensive laboratory testing is required, and too many foods exist to test them all anyway. Even individual food items that are the same exact variety of food – such as two Gala apples – can have different amounts of antioxidants. Where the food was grown and harvested, how it was processed and how it was stored during transportation and while in the supermarket are factors. The variety of the food also matters – the many different types of apples, for instance, can have different amounts of antioxidants.

Nonetheless, in 2018, researchers quantified the antioxidant content of more than 3,100 foods – the first antioxidant database. Each food’s antioxidant capacity was determined by the amount of oxidants neutralized by a given amount of food. The researchers measured this capacity in millimoles per 100 grams, or about 4 ounces.

For fruits easily found in the grocery store, the database shows blueberries have the most antioxidants – just over 9 millimoles per 4 ounces. The same serving of pomegranates and blackberries each have about 6.5 millimoles.

For common vegetables, cooked artichoke has 4.54 millimoles per 4 ounces; red kale, 4.09 millimoles; cooked red cabbage, 2.15; and orange bell pepper, 1.94.

Coffee has 2.5 millimoles per 4 ounces; green tea has 1.5; whole walnuts, just over 13; whole pecans, about 9.7; and sunflower seeds, just over 5. Herbs and spices have a lot: clove has 465 millimoles per 4 ounces; rosemary has 67; and thyme, about 64. But keep in mind that those enormous numbers are based on a quarter-pound. Still, just a normal sprinkle packs a powerful nutritional punch.

Other tips

Other ways to choose antioxidant-rich foods: Read the nutrition facts label and look for antioxidant vitamins and minerals – vitamins A, C, E, D, B2, B3 and B9, and the minerals selenium, zinc and manganese.

Just know the label has a drawback. Food producers and manufacturers are not required to list every nutrient of the food on the label. In fact, the only vitamins and minerals required by law are sodium, potassium, calcium, iron and vitamin D.

Also, focus on eating the rainbow. Colorful foods are often higher in antioxidants, like blue corn. Many darker foods are rich in antioxidants, too, like dark chocolate, black barley and dark leafy vegetables, such as kale and Swiss chard.

Although heat can degrade oxidants, that mostly occurs during the storage and transportation of the food. In some cases, cooking may increase the food’s antioxidant capacity, as with leafy green vegetables.

Keep in mind that while blueberries, red kale and pecans are great, their antioxidant profile will be different than that of other fruits, vegetables and nuts. That’s why diversity is the key: To increase the power of antioxidants, choose a variety of fresh, flavorful, colorful and, ideally, local foods.

Nathaniel Johnson, Assistant Professor of Nutrition and Dietetics, University of North Dakota

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Weather forecasting is a powerful tool. During hurricane season, for instance, meteorologists create computer simulations to forecast how these destructive storms form and where they might travel, which helps prevent damage to coastal communities. When you’re trying to forecast space weather, rather than storms on Earth, creating these simulations gets a little more complex. To simulate space weather, you would need to fit the Sun, the planets and the vast empty space between them in a virtual environment, also known as a simulation box, where all the calculations would take place.

Space weather is very different from the storms you see on Earth. These events come from the Sun, which ejects eruptions of charged particles and magnetic fields from its surface. The most powerful of these events are called interplanetary coronal mass ejections, or CMEs, which travel at speeds approaching 1,800 miles per second (2,897 kilometers per second).

To put that in perspective, a single CME could move a mass of material equivalent to all the Great Lakes from New York City to Los Angeles in just under two seconds – almost faster than it takes to say “space weather.”

When these CMEs hit Earth, they can cause geomagnetic storms, which manifest in the sky as beautiful auroras. These storms can also damage key technological infrastructure, such as by interfering with the flow of electricity in the power grid and causing transformers to overheat and fail.

To better understand how these storms can wreak so much havoc, our research team created simulations to show how storms interact with Earth’s natural magnetic shield and trigger the dangerous geomagnetic activity that can shut down electric grids.

In a study published in October 2025 in the Astrophysical Journal, we modeled one of the sources of these geomagnetic storms: small, tornado-like vortices spun off of an ejection from the Sun. These vortices are called flux ropes, and satellites had previously observed small flux ropes – but our work helped uncover how they are generated.

The challenge

Our team started this research in summer 2023, when one of us, a space weather expert, spotted inconsistencies in space weather observations. This work had found geomagnetic storms occurring during periods when no solar eruptions were predicted to hit Earth.

Bewildered, the space weather expert wanted to know if there could be space weather events that were smaller than coronal mass ejections and did not originate directly from solar eruptions. He predicted that such events might form in the space between the Sun and Earth, instead of in the Sun’s atmosphere.

One example of such smaller space weather events is a magnetic flux rope – bundles of magnetic fields wrapped around each other like a rope. Its detection in computer simulations of solar eruptions would hint to where these space weather events may be forming. Unlike satellite observations, in simulations you can turn back the clock or track an event upstream to see where they originate.

So he asked the other author, a leading simulation expert. It turned out that finding smaller space weather events was not as simple as simulating a big solar eruption and letting the computer model run long enough for the eruption to reach Earth. Current computer simulations are not meant to resolve these smaller events. Instead, they are designed to focus on the large solar eruptions because these have the most effects on infrastructure on Earth.

This shortfall was quite disappointing. It was like trying to forecast a hurricane with a simulation that only shows you global weather patterns. Because you can’t see a hurricane at that scale, you would completely miss it.

These larger-scale simulations are known as global simulations. They study how solar eruptions form on the Sun’s surface and travel through space. These simulations treat streams of charged particles and magnetic fields floating through space as fluids to reduce the computational cost, compared with modeling every charged particle independently. It’s like measuring the overall temperature of water in a bottle, instead of tracking every single water molecule individually.

Because these simulations are computational phenomena that happen across such a vast space, they can’t resolve every detail. To affordably resolve the vast space between the Sun and the planets, researchers divide the space into large cubes – analogous to two-dimensional pixels in a camera. In the simulation, these cubes each represent an area 1 million miles (1.6 million kilometers) wide, tall and across. That distance is equivalent to about 1% of the distance from Earth to the Sun.

The search begins

Our search began with what felt like hunting for a needle in a haystack. We were looking into old global simulations, searching for a tiny, transient blob – which would signify a flux rope – within an area of space hundreds of times wider than the Sun itself. Our initial search did not yield anything.

We then shifted our focus to the simulations of the May 2024 solar eruption event. This time, we specifically looked at the region where the solar eruption collided into a quiet flow of charged particles and magnetic fields, called the solar wind, ahead of it.

There it was: a distinct system of magnetic flux ropes.

However, our excitement was short-lived. We could not tell where these flux ropes came from. The modeled flux ropes were also too small to survive, eventually fizzling out because they became too small to resolve with our simulation grid.

But that was the type of clue we needed – the presence of flux ropes at the location where the solar eruption collided with the solar wind.

To settle the issue, we decided to bridge this gap and create a computer model with a finer grid size than those previous global simulations used. Since increasing the resolution across the entire simulation space would have been prohibitively expensive, we decided to only increase the simulation resolution along the trajectory of the flux ropes.

The new simulations could now resolve features that spanned distances six times Earth’s 8,000-mile (or 128,000-kilometer) diameter down to tens of thousands of miles – nearly 100 times better than previous simulations.

Making the discovery

Once we designed and tested the simulation grid, it was time to simulate that same solar eruption that led to the formation of those flux ropes in the less fine-grained model. We wanted to study the formation of those flux ropes and how they grew, changed shape and possibly terminated in the narrow wedge encompassing the space between the Sun and Earth. The results were astonishing.

The high-resolution view revealed that the flux ropes formed when the solar eruption slammed into the slower solar wind ahead of it. The new structures possessed incredible complexity and strength that persisted far longer than we expected. In meteorological terms, it was like watching a hurricane spawn a cluster of tornadoes.

We found that the magnetic fields in these vortices were strong enough to trigger a significant geomagnetic storm and cause some real trouble here on Earth. But most importantly, the simulations confirmed that there are indeed space weather events that form locally in the space between the Sun and Earth. Our next step is to simulate how such tornado-like features in the solar wind may impact our planet and infrastructure.

Watching these flux ropes in the simulation form so quickly and move toward Earth was exciting, but concerning. It was exciting because this discovery could help us better plan for future extreme space weather events. It was at the same time concerning because these flux ropes would only appear as a small blip in today’s space weather monitors.

We would need multiple satellites to directly see these flux ropes in greater detail so that scientists can more reliably predict whether, when and in what orientation they may affect our planet and what the outcome may be. The good news is that scientists and engineers are developing the next-generation space missions that could address this.

Mojtaba Akhavan-Tafti, Associate Research Scientist, University of Michigan and Ward B. (Chip) Manchester, Research Professor of Climate and Space Sciences Engineering, University of Michigan

This article is republished from The Conversation under a Creative Commons license. Read the original article.

There are almost 1.1 million licensed physicians in the United States. That may sound like a lot, but the country has struggled for decades to train enough physicians to meet its needs – and, in particular, to provide care in rural and underserved communities.

Foreign-born physicians have long filled that gap, reducing the overall national shortage and signing up to practice in often overlooked regions and specialties. Today, 1 in 5 doctors licensed to practice in the U.S. were born and trained in another country.

But the ability of physicians from other countries to obtain work in the U.S. may be threatened by the Trump administration’s aims of limiting foreign workers. In September, Trump issued a proclamation requiring employers sponsoring foreign-born workers through a type of work visa called an H-1B to pay a fee of US$100,000 to the government. The White House has signaled doctors may be exempt but has not clarified its position.

As a physician and professor who studies the intersection of business and medicine, I believe increasing restrictions on H-1B visas for physicians may exacerbate the physician shortage. To grasp why that is, it’s important to understand how foreign-trained doctors became such an integral part of U.S. health care – and the role they play today.

The roots of today’s physician shortage

The Association of American Medical Colleges, a trade association representing U.S. medical schools, estimates there will be a deficit of about 86,000 physicians in the country by 2036.

The roots of this shortage stretch back more than a century. In 1910, a landmark study called the Flexner Report detailed significant inconsistencies in the quality of education at American medical schools. The report resulted in the closure of over half the country’s medical schools, winnowing their numbers down from 148 to 66 over two decades.

As a result, the number of doctors in the U.S. declined until new training programs emerged. Between 1960 and 1980, 40 new medical schools launched with the help of federal funding. In 1980, a congressionally mandated assessment deemed the problem solved, but by the early 2000s, a physician shortage emerged once more. In 2006, the American Association of Medical Colleges called for raising medical school enrollment by 30%.

Growth in medical school enrollment hit that target in the late 2010s, but even so, the U.S. still lacks enough medical graduates to fill yearslong training programs, called residencies, that early-career physicians must complete to become fully qualified to practice.

Especially lacking are primary care physicians – particularly in rural areas, where there are one-third as many physicians per capita as in urban areas.

Opportunities for foreign-born doctors

Even as the U.S. built up medical school enrollment in the 1960s and 1970s, the government joined other countries such as the U.K. and Canada in creating immigration policies that drew physicians from developing countries to practice in underserved areas. Between 1970 and 1980, their numbers grew sharply, from 57,000 to 97,000.

Foreign-born and -trained physicians have remained a key pillar of the U.S. medical system. In recent years, the majority of those physicians have come from India and Pakistan. Citizens of Canada and Middle Eastern countries have added significantly to that count, as well. Most arrive in the U.S. as trainees in residency programs through one of two main visa programs.

The majority come on J-1 visas, which allow physicians to enter the U.S. for training but require them to return to their home country for at least two years when their training is complete. Those who wish to remain in the U.S. to practice must transition to an H-1B visa.

A small percentage of physicians come to the U.S. on H-1Bs from the start.

H-1B visas are employer-sponsored temporary work permits that allow foreign-born, highly skilled workers to obtain U.S. employment. Employers directly petition the government on behalf of visa applicants, certifying that a foreign worker will be paid a similar wage to U.S. workers and will not adversely affect the working conditions of Americans.

Several programs sponsor H-1B visas for physicians, though the most common requires a three-year commitment to work in an underserved area after completing their training.

Foreign physicians fill a crucial need

In 2025, foreign-trained medical graduates filled 9,700 of the nearly 40,000 training positions. Of those, roughly one-third were actually U.S. citizens who attended medical schools in other countries, with the remainder being foreign citizens seeking more training in the U.S.

After residency, these doctors frequently practice in precisely the geographic areas where the physician shortage is most severe. A nationwide survey of international medical graduates found that two-thirds practice in regions that the federal government has designated as lacking sufficient access to health care.

These doctors also occupy a disproportionate number of primary care positions. In a sample of 15,000 physicians who accepted new jobs in one year, foreign-born doctors were nine times more likely to enter primary care specialties. In 2025, 33.3% of internal medicine, 20.4% of pediatric and 17.6% of family medicine training positions were filled by physicians trained in other countries.

Who will pay?

Approximately 8,000 foreign-born physicians received H-1B visas in 2024. The new requirement of a $100,000 sponsorship fee would hit hardest for hospitals, health systems and clinics in areas of the country most significantly affected by the physician shortage.

These organizations are already under economic strain due to increasing labor costs and Medicare payments that have not kept pace with inflation. Dozens of these hospitals have closed in recent years, and many currently do not make enough money to support their operations.

On Sept. 25, 2025, 57 physician organizations cosigned a letter petitioning Homeland Security Secretary Kristi Noem to waive the new application fee for physicians.

Already, however, the new rule may be having a chilling effect. Despite years of annual growth in the number of foreign-born applicants to U.S. physician training programs, 2025 has seen a nearly 10% drop. If the new H-1B fee is applied to physicians, the number is likely to keep falling.

Patrick Aguilar, Managing Director of Health, Washington University in St. Louis

This article is republished from The Conversation under a Creative Commons license. Read the original article.