Using modern digital scanning techniques the researchers were able to shed new light on the fossil jawbone, which has been known since 1899 and been on display in the National Museum of Wales for many years, but was not correctly identified until now.

The fossil consists of natural molds of the jawbone in the rock and all the original bone has disappeared. So, using photo scanning, paleontology student Owain Evans was able to make a perfect 3D digital reconstruction to enable detailed study.

Owain Evans said: “This specimen has been referred to many times in scientific papers, but had yet to be successfully identified – we were not even sure whether it was dinosaur. It was named Zanclodon cambrensis by Edwin Tully Newton in 1899, but we knew the name Zanclodon had been abandoned as referring to a broad variety of early reptiles. Therefore, we name it after Newton, calling it Newtonsaurus. It is different from all other dinosaurs from around that time, and requires a distinctive name.”

Professor Michael J Benton, who is the senior author on the paper, said: “The natural molds of the inner and outer faces of the jawbone show amazing detail – every groove, ridge, tooth, and even the serrations along the edges of the teeth. We decided to use digital photography to make a 3D model. We began by surface scanning the fossil using photogrammetry. Once we had our digital scan, we then inverted it – essentially giving us a digital negative of the mold. It was then a simple case of fusing the two sides together and analyzing the anatomy from there. The digital reconstruction we have extracted from the specimen gives a much better idea of what the original structure of the bone would have looked like.”

Now that the fossil could be studied, the team was able to use its anatomy to piece together its position in the reptile family tree – and most crucially – whether it was a dinosaur or not.

Owain Evans said: “We can now confirm that this specimen very likely belonged to a large predatory theropod dinosaur, that roamed the shores of South Wales during the latest Triassic. It has some definite unique dinosaur features in the emplacement of the teeth, and it is a theropod — a predatory, flesh-eating dinosaur. Otherwise, it sits near the origins of both major divisions of Theropoda, the Coelophysoidea and the Averostra.

“Most unexpected is the size of the animal. The preserved jawbone is 28 cm long, and that is just the front half, so originally the jawbone was 60 cm long, corresponding to a dinosaur with a body length of 5-7 meters. This is unusually large for a Triassic theropod, most of which were half the size or smaller.”

Cindy Howells at the National Museum of Wales said: “These historical specimens are vitally important in paleontology and often yield new and exciting results – even if they have been sitting in collections for years. The Victorians were fascinated by the fossil record and prospected all across the UK for fossils. On top of this, the re-description of Newtonsaurus cambrensis once again highlights the significance of Wales in paleontological research. These Triassic beds are rare worldwide, and yet there are several across Wales. There might very well be another dinosaur waiting to be discovered.”

The design uses layers of metamaterials to simultaneously focus a range of wavelengths from an unpolarized source and over a large diameter, overcoming a major limitation of metalenses, said the first author of the paper reporting the design, Mr Joshua Jordaan, from the Research School of Physics at the Australian National University and the ARC Centre of Excellence for Transformative Meta-Optical Systems (TMOS).

“Our design has a lot of nice features that make it applicable to practical devices.”

“It’s easy to manufacture because it has a low aspect ratio and each layer can be fabricated individually and then packaged together, it’s also polarisation insensitive, and is potentially scalable through mature semiconductor nanofabrication platforms,” Mr Jordaan said.

The project was led by researchers from the Friedrich Schiller University Jena in Germany as part of the International Research Training Group Meta-ACTIVE. The paper reporting their design is published in Optics Express.

Metalenses have thickness mere fractions of the width of a hair, which is orders of magnitude thinner than conventional lenses. They can be designed to have properties such as focal lengths that would be impossibly short for conventional optics.

Initially the team attempted to focus multiple wavelengths with a single layer, but they hit up against some fundamental constraints, Mr Jordaan said.

“It turns out the maximum group-delay attainable in a single-layer metasurface has physical limitations, and these in turn set upper bounds on the product of the numerical aperture, physical diameter and operating bandwidth.”

“To work at the wavelength range we needed, a single layer would either have to have a very small diameter, which would defeat the purpose of the design, or basically have such a low numerical aperture that it’s hardly focusing the light at all,” he said.

“We realized we needed a more complex structure, which then led to a multi-layer approach.”

With the design shifted to incorporating several metalens layers, the team approached the problem with an inverse design algorithm based on shape optimization, with parameterization that meant a lot of degrees of freedom.

They guided the software to search for metasurface shapes that, for a single wavelength, created simple resonances in both the electric and magnetic dipole, known as Huygens resonances. By employing resonances, the team were able to improve on previous designs by other groups, and develop metalens designs that were polarization independent, and had greater tolerances in manufacturing specifications – crucial in the quest to scale fabrication to industrial quantities.

The optimization routine came up with a library of metamaterial elements in a surprising range of shapes, such as rounded squares, four-leaf clovers and propellers.

These tiny shapes, around 300 nm tall and 1000 nm wide, spanned the full range of phase shifts, from zero to two pi, enabling the team to create a phase gradient map to achieve any arbitrary focusing pattern – although they were initially just aiming for a simple ring structure of a conventional lens.

“We could, for example, focus different wavelengths into different locations to create a colour router,” Mr Jordaan said.

However, the multilayer approach is limited to a maximum of around five different wavelengths, Mr Jordaan said.

“The problem is you need structures large enough to be resonant at the longest wavelength, without getting diffraction from the shorter wavelengths,” he said.

Within these constraints, Mr Jordaan said the ability to make metalenses to collect a lot of light will be a boon for future portable imaging systems.

“The metalenses we have designed would be ideal for drones or earth-observation satellites, as we’ve tried to make them as small and light as possible,” he said.

Now, scientists led by Northwestern University and Soochow University in China have built the first perovskite-based detector that can capture individual gamma rays for SPECT imaging with record-breaking precision. The new tool could make common types of nuclear medicine imaging sharper, faster, cheaper and safer.

For patients, that could mean shorter scan times, clearer results and lower doses of radiation.

The study was published on Aug. 30 in the journal Nature Communications.

“Perovskites are a family of crystals best known for transforming the field of solar energy,” said Northwestern’s Mercouri Kanatzidis, the study’s senior author. “Now, they are poised to do the same for nuclear medicine. This is the first clear proof that perovskite detectors can produce the kind of sharp, reliable images that doctors need to provide the best care for their patients.”

“Our approach not only improves the performance of detectors but also could lower costs,” said co-corresponding author Yihui He, a professor at Soochow University. “That means more hospitals and clinics eventually could have access to the best imaging technologies.”

Kanatzidis is a Charles E. and Emma H. Morrison Professor of Chemistry at Northwestern’s Weinberg College of Arts and Sciences and a senior scientist at Argonne National Laboratory. Yihui He is a former postdoctoral fellow from Kanatzidis’ laboratory.

Nuclear medicine, like SPECT (single-photon emission computing tomography) imaging, works like an invisible camera. Physicians implant a tiny, safe, short-lived radiotracer in a specific part of a patient’s body. The tracer emits gamma rays, which pass outward through tissues and eventually hit a detector outside of the body. Each gamma ray is like a pixel of light. After collecting millions of these pixels, computers can construct a 3D image of working organs.

Today’s detectors, which are either made from cadmium zinc telluride (CZT) or sodium iodide (NaI), have several disadvantages. CZT detectors are incredibly expensive, sometimes reaching into the price range of hundreds of thousands to millions of dollars for a whole camera. Because CZT crystals are brittle and prone to cracking, these detectors also are difficult to manufacture. While cheaper than CZT detectors, NaI detectors are bulky and produce blurrier images — like taking a photo through a foggy window.

To overcome these issues, the scientists turned to perovskite crystals, a material that Kanatzidis has studied for more than a decade. In 2012, his group built the first solid-film solar cells made from perovskites. Then, in 2013, Kanatzidis discovered that single perovskite crystals were highly promising for detecting X-rays and gamma rays. This breakthrough, enabled by his group’s growth of high-quality single crystals, sparked a worldwide surge of research and effectively launched a new field in hard radiation detection materials.

“This work demonstrates how far we can push perovskite detectors beyond the laboratory,” Kanatzidis said. “When we first discovered in 2013 that perovskite single crystals could detect X-rays and gamma rays, we could only imagine their potential. Now, we’re showing that perovskite-based detectors can deliver the resolution and sensitivity needed for demanding applications like nuclear medicine imaging. It’s exciting to see this technology moving closer to real-world impact.”

Building on this foundation, Kanatzidis and He led the crystal growth, surface engineering and device design for the new study. By carefully growing and shaping these crystals, the researchers created a pixelated sensor — just like the pixels in a smartphone camera — that delivers record-breaking clarity and stability.

Leading the design and development of the prototype gamma-ray detector, He developed the camera’s pixelated architecture, optimized the multi-channel readout electronics and carried out the high-resolution imaging experiments that validated the device’s capabilities. He, Kanatzidis and their team demonstrated that perovskite-based detectors can achieve record energy resolutions and unprecedented single-photon imaging performance, paving the way for practical integration into next-generation nuclear medicine imaging systems.

“Designing this gamma-ray camera and demonstrating its performance has been incredibly rewarding,” He said. “By combining high-quality perovskite crystals with a carefully optimized pixelated detector and multi-channel readout system, we were able to achieve record-breaking energy resolution and imaging capabilities. This work shows the real potential of perovskite-based detectors to transform nuclear medicine imaging.”

In experiments, the detector was able to differentiate among gamma rays of different energies with the best resolution reported thus far. It also sensed extremely faint signals from a medical radiotracer (technetium-99m) commonly used in clinical practice and distinguished incredibly fine features, producing crisp images that could separate tiny radioactive sources spaced just a few millimeters apart. The detector also remained highly stable, collecting nearly all the tracer’s signal without loss or distortion. Because these new detectors are more sensitive, patients potentially could require shorter scan times or smaller doses of radiation.

Northwestern spinout company Actinia Inc. is commercializing this technology — working with partners in the medical device field to bring it out of the lab and into hospitals. Because they are easier to grow and use simpler components, perovskites offer a far less expensive alternative to CZT and NaI detectors without sacrificing quality. Perovskite-based detectors also offer a realistic pathway to imaging using a lower dose of a radiotracer than can be used with a NaI detector but at a price that ensures widespread patient access.

“Demonstrating that perovskites can deliver single-photon gamma-ray imaging is a milestone,” He said. “It shows these materials are ready to move beyond the laboratory and into technologies that directly benefit human health. From here, we see opportunities to refine the detectors further, scale up production and explore entirely new directions in medical imaging.”

“High-quality nuclear medicine shouldn’t be limited to hospitals that can afford the most expensive equipment,” Kanatzidis said. “With perovskites, we can open the door to clearer, faster, safer scans for many more patients around the world. The ultimate goal is better scans, better diagnoses and better care for patients.”

The study, “Single photon γ-ray imaging with high energy and spatial resolution perovskite semiconductor for nuclear medicine,” was supported by the Defense Threat Reduction Agency (award number HDTRA12020002), the Consortium for Interaction of Ionizing Radiation with Matter University Research Alliance, the National Key R&D Program of China (award number 2021YFF0502600), the National Natural Science Foundation of China (award number U2267211) and the Jiangsu Natural Science Foundation (award number BK20240822).

“This milestone represents decades of cosmic exploration driven by NASA space telescopes — exploration that has completely changed the way humanity views the night sky,” said Shawn Domagal-Goldman, acting director, Astrophysics Division, NASA Headquarters in Washington. “Step by step, from discovery to characterization, NASA missions have built the foundation to answering a fundamental question: Are we alone? Now, with our upcoming Nancy Grace Roman Space Telescope and Habitable Worlds Observatory, America will lead the next giant leap — studying worlds like our own around stars like our Sun. This is American ingenuity, and a promise of discovery that unites us all.”

The milestone comes 30 years after the first exoplanet was discovered around a star similar to our Sun, in 1995. (Prior to that, a few planets had been identified around stars that had burned all their fuel and collapsed.) Although researchers think there are billions of planets in the Milky Way galaxy, finding them remains a challenge. In addition to discovering many individual planets with fascinating characteristics as the total number of known exoplanets climbs, scientists are able to see how the general planet population compares to the planets of our own solar system.

For example, while our solar system hosts an equal number of rocky and giant planets, rocky planets appear to be more common in the universe. Researchers have also found a range of planets entirely different from those in our solar system. There are Jupiter-size planets that orbit closer to their parent star than Mercury orbits the Sun; planets that orbit two stars, no stars, and dead stars; planets covered in lava; some with the density of Styrofoam; and others with clouds made of gemstones.

“Each of the different types of planets we discover gives us information about the conditions under which planets can form and, ultimately, how common planets like Earth might be, and where we should be looking for them,” said Dawn Gelino, head of NASA’s Exoplanet Exploration Program (ExEP), located at the agency’s Jet Propulsion Laboratory in Southern California. “If we want to find out if we’re alone in the universe, all of this knowledge is essential.”

Searching for other worlds

Fewer than 100 exoplanets have been directly imaged, because most planets are so faint they get lost in the light from their parent star. The other four methods of planet detection are indirect. With the transit method, for instance, astronomers look for a star to dim for a short period as an orbiting planet passes in front of it.

To account for the possibility that something other than an exoplanet is responsible for a particular signal, most exoplanet candidates must be confirmed by follow-up observations, often using an additional telescope, and that takes time. That’s why there is a long list of candidates in the NASA Exoplanet Archive (hosted by NExScI) waiting to be confirmed.

“We really need the whole community working together if we want to maximize our investments in these missions that are churning out exoplanets candidates,” said Aurora Kesseli, the deputy science lead for the NASA Exoplanet Archive at IPAC. “A big part of what we do at NExScI is build tools that help the community go out and turn candidate planets into confirmed planets.”

The rate of exoplanet discoveries has accelerated in recent years (the database reached 5,000 confirmed exoplanets just three years ago), and this trend seems likely to continue. Kesseli and her colleagues anticipate receiving thousands of additional exoplanet candidates from the ESA (European Space Agency) Gaia mission, which finds planets through a technique called astrometry, and NASA’s upcoming Nancy Grace Roman Space Telescope, which will discover thousands of new exoplanets primarily through a technique called gravitational microlensing.

Future exoplanets

At NASA, the future of exoplanet science will emphasize finding rocky planets similar to Earth and studying their atmospheres for biosignatures — any characteristic, element, molecule, substance, or feature that can be used as evidence of past or present life. NASA’s James Webb Space Telescope has already analyzed the chemistry of over 100 exoplanet atmospheres.

But studying the atmospheres of planets the size and temperature of Earth will require new technology. Specifically, scientists need better tools to block the glare of the star a planet orbits. And in the case of an Earth-like planet, the glare would be significant: The Sun is about 10 billion times brighter than Earth — which would be more than enough to drown out our home planet’s light if viewed by a distant observer.

NASA has two main initiatives to try overcoming this hurdle. The Roman telescope will carry a technology demonstration instrument called the Roman Coronagraph that will test new technologies for blocking starlight and making faint planets visible. At its peak performance, the coronagraph should be able to directly image a planet the size and temperature of Jupiter orbiting a star like our Sun, and at a similar distance from that star. With its microlensing survey and coronagraphic observations, Roman will reveal new details about the diversity of planetary systems, showing how common solar systems like our own may be across the galaxy.

Additional advances in coronagraph technology will be needed to build a coronagraph that can detect a planet like Earth. NASA is working on a concept for such a mission, currently named the Habitable Worlds Observatory.

More about ExEP, NExScI

NASA’s Exoplanet Exploration Program is responsible for implementing the agency’s plans for the discovery and understanding of planetary systems around nearby stars. It acts as a focal point for exoplanet science and technology and integrates cohesive strategies for future discoveries. The science operations and analysis center for ExEP is NExScI, based at IPAC, a science and data center for astrophysics and planetary science at Caltech. JPL is managed by Caltech for NASA.

The research was published on Sept. 18 in the journal Science, and is an important step towards building large-scale quantum computers – one of the most exciting scientific and technological challenges of the 21^st century.

Lead author Dr Holly Stemp says the achievement unlocks the potential to build the future microchips needed for quantum computing using existing technology and manufacturing processes.

“We succeeded in making the cleanest, most isolated quantum objects talk to each other, at the scale at which standard silicon electronic devices are currently fabricated,” she says.

The challenge facing quantum computer engineers has been to balance two opposing needs: shielding the computing elements from external interference and noise, while still enabling them to interact to perform meaningful computations. This is why there are so many different types of hardware still in the race to be the first operating quantum computer: some are very good for performing fast operations, but suffer from noise; others are well shielded from noise, but difficult to operate and scale up.

The UNSW team has invested on a platform that – until today – could be placed in the second camp. They have used the nuclear spin of phosphorus atoms, implanted in a silicon chip, to encode quantum information.

“The spin of an atomic nucleus is the cleanest, most isolated quantum object one can find in the solid state,” says Scientia Professor Andrea Morello, UNSW School of Electrical Engineering & Telecommunications.

“Over the last 15 years, our group has pioneered all the breakthroughs that made this technology a real contender in the quantum computing race. We already demonstrated that we could hold quantum information for over 30 seconds – an eternity, in the quantum world – and perform quantum logic operations with less than 1% errors.

“We were the first in the world to achieve this in a silicon device, but it all came at a price: the same isolation that makes atomic nuclei so clean, makes it hard to connect them together in a large-scale quantum processor.”

Until now, the only way to operate multiple atomic nuclei was for them to be placed very close together inside a solid, and to be surrounded by one and the same electron.

“Most people think of an electron as the tiniest subatomic particle, but quantum physics tells us that it has the ability to ‘spread out’ in space, so that it can interact with multiple atomic nuclei,” says Dr Holly Stemp, who conducted this research at UNSW and is now a postdoctoral researcher at MIT in Boston.

“Even so, the range over which the electron can spread is quite limited. Moreover, adding more nuclei to the same electron makes it very challenging to control each nucleus individually.”

Making atomic nuclei talk through electronic ‘telephones’

“By way of metaphor one could say that, until now, nuclei were like people placed in a sound-proof room,” Dr Stemp says.

“They can talk to each other as long as they are all in the same room, and the conversations are really clear. But they can’t hear anything from the outside, and there’s only so many people who can fit inside the room. This mode of conversation doesn’t ‘scale’.

“With this breakthrough, it’s as if we gave people telephones to communicate to other rooms. All the rooms are still nice and quiet on the inside, but now we can have conversations between many more people, even if they are far away.”

The ‘telephones’ are, in fact, electrons. Mark van Blankenstein, another author on the paper, explains what’s really going on at the sub-atomic level.

“By their ability to spread out in space, two electrons can ‘touch’ each other at quite some distance. And if each electron is directly coupled to an atomic nucleus, the nuclei can communicate through that.”

So how far apart were the nuclei involved in the experiments?

“The distance between our nuclei was about 20 nanometers – one thousandth of the width of a human hair,” says Dr Stemp.

“That doesn’t sound like much, but consider this: if we scaled each nucleus to the size of a person, the distance between the nuclei would be about the same as that between Sydney and Boston!”

She adds that 20 nanometers is the scale at which modern silicon computer chips are routinely manufactured to work in personal computers and mobile phones.

“You have billions of silicon transistors in your pocket or in your bag right now, each one about 20 nanometers in size. This is our real technological breakthrough: getting our cleanest and most isolated quantum objects talking to each other at the same scale as existing electronic devices. This means we can adapt the manufacturing processes developed by the trillion-dollar semiconductor industry, to the construction of quantum computers based on the spins of atomic nuclei.”

A scalable way forward

Despite the exotic nature of the experiments, the researchers say these devices remain fundamentally compatible with the way all current computer chips are built. The phosphorus atoms were introduced in the chip by the team of Professor David Jamieson at the University of Melbourne, using an ultra-pure silicon slab supplied by Professor Kohei Itoh at Keio University in Japan.

By removing the need for the atomic nuclei to be attached to the same electron, the UNSW team has swept aside the biggest roadblock to the scale-up of silicon quantum computers based on atomic nuclei.

“Our method is remarkably robust and scalable. Here we just used two electrons, but in the future we can even add more electrons, and force them in an elongated shape, to spread out the nuclei even further,” Prof. Morello says.

“Electrons are easy to move around and to ‘massage’ into shape, which means the interactions can be switched on and off quickly and precisely. That’s exactly what is needed for a scalable quantum computer.”

“It’s called colorized hyperspectral X-ray imaging with multi-metal targets, or CHXI MMT for short,” said project lead Edward Jimenez, an optical engineer. Jimenez has been working with materials scientist Noelle Collins and electronics engineer Courtney Sovinec to create X-rays of the future.

“With this new technology, we are essentially going from the old way, which is black and white, to a whole new colored world where we can better identify materials and defects of interest,” Collins said.

The team found they could achieve this using tiny, patterned samples of varied metals such as tungsten, molybdenum, gold, samarium and silver.

The Basics of X-ray Creation

To understand the concept, one must understand the basics of X-ray creation. Traditional X-rays are generated by bombarding a single metal target, or anode, with high-energy electrons. Those X-rays are channeled into a beam and directed at a subject or material. Denser tissues, like bone, absorb more X-rays, while less dense tissues, like muscles and organs allow more to pass through. A detector records the pattern, creating an image.

While X-ray technology has advanced over time, the basic concept remains the same, which limits resolution and clarity.

A New Type of X-Ray Image

The Sandia team set out to solve that limitation by making the X-ray focal spot smaller. The smaller the spot, the sharper the image.

They achieved this by designing an anode with metal dots patterned to be collectively smaller than the beam, effectively reducing the focal point.

But the team decided they wanted to push the limits and took the concept a step further.

“We chose different metals for each dot,” Sovinec said. “Each metal emits a particular ‘color’ of X-ray light. When combined with an energy discriminating detector, we can count individual photons, which provide density information, and measure the energy of each photon. This allows us to characterize the elements of the sample.”

The result is colorized images with what the team calls revolutionary image clarity and a better understanding of an object’s composition.

“We get a more accurate representation of the shape and definition of that object, which is going to allow us to make unprecedented measurements and unprecedented observations,” Jimenez said.

Far-reaching applications

The team sees this as a major advancement for X-ray technology with a wide range of uses, from airport security and quality control to nondestructive testing and advanced manufacturing.

They also hope its impact will improve medical diagnostics.

“With this technology, you can see even slight differences between materials,” Jimenez said. “We hope this will help better identify things like cancer and more effectively analyze tumor cells. In mammography you are trying to catch something before it grows. In breast tissue, it’s hard to identify the different dots, but with colorization you have a sharper beam and higher resolution image that increases the system’s capability to detect a microcalcification. It’s really exciting to be a part of that.”

“From here we will continue to innovate,” Collins said. “We hope to identify threats faster, diagnose diseases quicker and hopefully create a safer, healthier world.”

The team was recently awarded an R&D 100 award for their technology. They were among six winners from Sandia. Click for R&D 100 Submission video with soundbites.

High blood pressure occurs when the force of blood flowing through the blood vessels is consistently too high. High blood pressure can lead to other serious events such as heart attack and stroke. Using data from 2017 to 2020, 122.4 million (46.7%) adults in the U.S. had high blood pressure and it contributed to more than 130,000 deaths. Too much sodium and too little potassium in the diet are risk factors for high blood pressure.

“Overall, less than 6% of all U.S. adults use salt substitutes, even though they are inexpensive and can be an effective strategy to help people control blood pressure, especially people with difficult-to-treat high blood pressure,” said lead study author Yinying Wei, M.C.N., R.D.N., L.D., and Ph.D. candidate in the departments of applied clinical research and hypertension section, cardiology division, at UT Southwestern Medical Center in Dallas. “Health care professionals can raise awareness about the safe use of salt substitutes by having conversations with their patients who have persistent or hard-to-manage high blood pressure.”

Salt substitutes are products that replace some or all of the sodium with potassium. Potassium salt tastes similar to regular salt, except when heated it can have a bitter aftertaste. Many foods contain some sodium in their natural state, however, the largest amount of sodium comes from processed and packaged foods and meals prepared at restaurants. The American Heart Association recommends consuming no more than 2,300 mg of sodium a day, with an ideal limit of less than 1,500 mg per day for most adults, especially for those with high blood pressure. For most people, cutting back by 1,000 mg a day can improve blood pressure and heart health.

This study is the first to examine long-term trends in salt substitute use among a nationally representative sample of U.S. adults. Using data from the National Health and Nutrition Examination Survey (NHANES) from 2003 to 2020, researchers analyzed the use of products that replace salt with potassium-enriched or other alternative salts.

The investigation focused on people with high blood pressure, and an additional analysis was conducted among adults eligible to use salt substitutes, including people with normal kidney function and those not taking medications or supplements that affect blood potassium levels. Some salt substitutes contain potassium, and they can raise blood potassium to dangerous levels in people with kidney disease or those taking certain medications or potassium supplements. Excessive potassium can lead to irregular heart rhythms. People with high blood pressure who are thinking about switching from regular salt to a salt substitute should first consult with a health care professional.

The analysis found:

• Overall, salt substitute use among all U.S. adults remained low, peaking at 5.4% in 2013-2014 before falling to 2.5% by 2017-March 2020. Data collection for 2020 stopped before March because of the pandemic.
• Among adults eligible to use salt substitutes, only 2.3% to 5.1% did so.
• Usage was highest in people with high blood pressure whose BP was controlled with medications (3.6%-10.5%), followed by those with high blood pressure whose BP was not controlled despite medications (3.7%-7.4%).
• Salt substitute use remained consistently less than 5.6% among people with untreated high blood pressure and for people with normal blood pressure.
• Adults who ate at restaurants three or more times a week appeared less likely to use salt substitutes compared to those who ate out less often, but this difference was no longer statistically significant after accounting for age, race/ethnicity, education level and insurance status.

“Salt substitute use remained uncommon over the last two decades including among people with high blood pressure,” Wei said. “Even among individuals with treated and poorly managed or untreated high blood pressure, most continued to use regular salt.”

“This study highlights an important and easy missed opportunity to improve blood pressure in the U.S. — the use of salt substitutes,” said Amit Khera, M.D., M.Sc., FAHA, an American Heart Association volunteer expert. “The fact that use of salt substitutes remains so low and has not improved in two decades is eye-opening and reminds patients and health care professionals to discuss the use of these substitutes, particularly in visits focused on high blood pressure.” Khera, who was not involved in this study, is a professor of medicine, clinical chief of cardiology and director of preventive cardiology at UT Southwestern Medical Center in Dallas.

The study has several limitations. First, information about salt substitute use was self-reported, so there may have been underreporting or misclassification. In addition, all types of salt substitutes were included in the analysis, therefore, the analysis could not specifically separate potassium-enriched salt from other types of salt substitutes. Finally, the survey data did not capture how much salt substitute the participants used.

“Future research should explore why salt substitute-use remains low by investigating potential barriers, such as taste acceptance, cost and limited awareness among both patients and clinicians,” said Wei. “These insights may help guide more targeted interventions.”

Study details, background and design:

• The analysis included 37,080 adults, ages 18 and older (37.9% were aged 18-39, 36.9% were aged 40-59 years, and 25.2% were aged 60 and older). 50.6% of participants were women, 10.7% of participants self-reported their race as non-Hispanic Black, and 89.3% self-reported they were from other racial and ethnic groups.
• Participants were categorized into four subgroups based on presence or absence of high blood pressure (≥130/80 mm Hg) and whether they were using blood pressure lowering medication: 1) high blood pressure that was treated and controlled; 2) high blood pressure that was treated and not controlled; 3) untreated high blood pressure; and 4) those with normal blood pressure.
• Salt types were classified as ordinary salt (iodized salt, sea salt, kosher salt), salt substitute (potassium-enriched or other salt substitute) and no salt use.
• An additional analysis was conducted on a subgroup of individuals eligible to use salt substitutes — those with healthy kidney function (estimated glomerular filtration rate ≥ 60) and not taking medications or supplements that affect blood potassium levels.
• The frequency of eating at restaurants to assess its influence on salt substitute use was also evaluated.
• All analyses incorporated NHANES sampling weights and complex survey design.

Research Highlights:

• Despite their effectiveness in lowering sodium intake and managing blood pressure, salt substitutes were rarely used by people with high blood pressure, according to a review of almost 20 years of U.S. health survey data.
• Researchers recommend increasing awareness of salt substitutes as a strategy to help effectively treat blood pressure, especially for individuals with difficult-to-treat or treatment-resistant high blood pressure.
• The study is supported by a grant from the National Institutes of Health.
• Note: The study featured in this news release is a research abstract. Abstracts presented at American Heart Association‘s scientific meetings are not peer-reviewed, and the findings are considered preliminary until published as a full manuscript in a peer-reviewed scientific journal.