Too much of this ingredient leads to autoimmune diseases, new research shows. Here's how to cut back.
Scientists are looking at how salt affects our cells, and they're finding more reasons to avoid htoo much of it.
For more than a century, doctors have warned that too much salt in your diet can lead to high blood pressure, heart disease and stroke - and many of the reasons for these effects are well known. But recently scientists have been looking deeper, into the cellular level, and they are finding additional reasons to minimize sodium intake; it is bad for immune cells, creating patterns of gene expression and activity seen in a variety of autoimmune diseases such as multiple sclerosis, lupus, rheumatoid arthritis, and type-1 diabetes.
Salt is a major part of the ocean from which life evolved on this planet. We carry that legacy in our blood, which tastes salty. It is an important element for conducting electrical signals along nerves and balancing water and metabolites transported throughout our bodies. We need to consume about 500 milligrams of salt each day to maintain these functions, more with exercise and heavy sweating as that is a major way the body loses salt. The problem is that most Americans eating a modern western diet consume about 3400 milligrams, 1.5 teaspoons per day.
Evidence has been accumulating over the last few years that elevated levels of sodium can be harmful to at least some types of immune cells. The first signal came in monocytes, which are immune cells that travel to various tissues in the body, where some of them turn into macrophages, a subset of white blood cells that can directly kill microorganisms and make chemical signals that bring other types of immune cells into play.
Two years ago, Dominik N. Müller from the Max-Delbrueck-Center in Berlin, Germany and Markus Kleinewietfeld, an immunologist at Hasselt University in Belgium, ran a study where they fed people pizza and then measured their immune cell function. “We saw that in any monocytes, metabolic function was down, even after a single salty meal,” Kleinewietfeld says. It seemed to be the cellular equivalent of the sluggish feeling we get after eating too much. The cells were able to recover but more research is needed to answer questions about what dose of sodium causes impairment, how long the damage lasts, and whether there is a cumulative effect of salt toxicity.
Kleinewietfeld and his colleagues have hypothesized that too much salt could be a significant factor in the increased number of autoimmune diseases and allergies over the last few generations.
The latest series of experiments focused on a type of T cell called T regulatory cells, or Tregs. Most T cells release inflammatory mediators to fight pathogens and, once that job is done, Tregs come along to calm down their hyperactive brethren. Failure to do so can result in continued inflammation and possibly autoimmune diseases.
In the lab, Kleinewietfeld and his large team of international collaborators saw that high levels of sodium had a huge effect on Tregs, upregulating 1250 genes and downregulating an additional 1380 genes so that they looked similar to patterns of gene expression seen in autoimmune diseases.
Digging deeper, they found that sodium affected mitochondria, the tiny organelles inside of cells that produce much of its energy. The sodium was interfering with how the mitochondria use oxygen, which resulted in increased levels of an unstable form of oxygen that can damage cell function. The researchers injected those damaged Tregs into mice and found that they impaired the animals' immune function, allowing the inflammation to continue rather than shutting it down.
That finding dovetailed nicely with a 2019 paper in Nature from Navdeep Chandel's lab at Northwestern University, which showed in mice that inhibiting the mitochondrial use of oxygen reduced the ability of Tregs to regulate other T cells. “Mitochondria were controlling directly the immunosuppressive program, they were this master regulator tuning the right amount of genes to give you proper immunosuppression,” Chandel said. “And if you lose that function, then you get autoimmunity.”
Kleinewietfeld's team studied the Treg cells of humans and found that sodium can similarly decrease mitochondrial use of oxygen and immunosuppressive activity. “I would have never predicted that myself,” Chandel says, but now researchers can look at the mitochondria of patients with autoimmune disease and see if their gene expression also changes under high salt conditions. He sees the link between the patterns of gene expression in Tregs generated by high salt exposure and those patterns seen in autoimmune diseases, but he is cautious about claiming a causal effect.
Kleinewietfeld and his colleagues have hypothesized that too much salt could be a significant factor in the increased number of autoimmune diseases and allergies over the last few generations. He says a high salt diet could also have an indirect effect on immune function through the way it affects the gut microbiome and the molecules made by microbes when they break down food. But the research results are too preliminary to say that for sure, much less parse out the role of salt compared with other possible factors. “It is still an exciting journey to try to understand this field,” he says.
Additionally, it is difficult to say precisely how this research in animals and human cell cultures will translate into a whole human body. Individual differences in genetics can affect how the body absorbs, transports, and gets rid of sodium, such that some people are more sensitive to salt than are others.
So how should people apply these research findings to daily life?
Salt is obvious when we sprinkle it on at the table or eat tasty things like potato chips, but we may be unaware of sodium hidden in packaged foods. That's because salt is an easy and cheap way to boost the flavor of foods. And if we do read the labeled salt content on a package, we focus on the number for a single serving, but then eat more than that.
Last September, the U.S. Food and Drug Administration (FDA) began a process to update labels on the content of food, including what is meant by the word “healthy” and how food manufacturers can use the term. Many in the food industry are resisting those proposed changes.
Chandel cautions against trying to counter the effects of salt by reaching for foods or supplements full of antioxidants, which, in theory, could reduce the harmful effects on mitochondria caused by a heavy hand with the salt shaker.
Until labels are updated, it would be prudent to try to reduce sodium intake by cutting down on packaged foods while making your own food at home, where you know just how much salt has been added. The Mayo Clinic offers guidance on how to become more aware of the sodium in your diet and eat less of it.
Chandel thinks many people will struggle with minimizing salt in their diets. It’s similar to the challenge of eating less sugar, in that the body craves both, and it is difficult to fight that. He cautions against trying to counter the effects of salt by reaching for foods or supplements full of antioxidants, which, in theory, could reduce the harmful effects on mitochondria caused by a heavy hand with the salt shaker. “Dietary antioxidants have failed in just about every clinical trial, yet the public continues to take them,” Chandel says. But he is optimistic that research will lead us to a better understanding of how Tregs function, and uncover new targets for treating autoimmune diseases.
The upcoming vaccine is changing the way we look at treating one of the country’s deadliest cancers.
Last week, researchers at the University of Oxford announced that they have received funding to create a brand new way of preventing ovarian cancer: A vaccine. The vaccine, known as OvarianVax, will teach the immune system to recognize and destroy mutated cells—one of the earliest indicators of ovarian cancer.
Understanding Ovarian Cancer
Despite advancements in medical research and treatment protocols over the last few decades, ovarian cancer still poses a significant threat to women’s health. In the United States alone, more than 12,0000 women die of ovarian cancer each year, and only about half of women diagnosed with ovarian cancer survive five or more years past diagnosis. Unlike cervical cancer, there is no routine screening for ovarian cancer, so it often goes undetected until it has reached advanced stages. Additionally, the primary symptoms of ovarian cancer—frequent urination, bloating, loss of appetite, and abdominal pain—can often be mistaken for other non-cancerous conditions, delaying treatment.
An American woman has roughly a one percent chance of developing ovarian cancer throughout her lifetime. However, these odds increase significantly if she has inherited mutations in the BRCA1 or BRCA2 genes. Women who carry these mutations face a 46% lifetime risk for ovarian and breast cancers.
An Unlikely Solution
To address this escalating health concern, the organization Cancer Research UK has invested £600,000 over the next three years in research aimed at creating a vaccine, which would destroy cancerous cells before they have a chance to develop any further.
Researchers at the University of Oxford are at the forefront of this initiative. With funding from Cancer Research UK, scientists will use tissue samples from the ovaries and fallopian tubes of patients currently battling ovarian cancer. Using these samples, University of Oxford scientists will create a vaccine to recognize certain proteins on the surface of ovarian cancer cells known as tumor-associated antigens. The vaccine will then train that person’s immune system to recognize the cancer markers and destroy them.
The next step
Once developed, the vaccine will first be tested in patients with the disease, to see if their ovarian tumors will shrink or disappear. Then, the vaccine will be tested in women with the BRCA1 or BRCA2 mutations as well as women in the general population without genetic mutations, to see whether the vaccine can prevent the cancer altogether.
While the vaccine still has “a long way to go,” according to Professor Ahmed Ahmed, Director of Oxford University’s ovarian cancer cell laboratory, he is “optimistic” about the results.
“We need better strategies to prevent ovarian cancer,” said Ahmed in a press release from the University of Oxford. “Currently, women with BRCA1/2 mutations are offered surgery which prevents cancer but robs them of the chance to have children afterward.
Teaching the immune system to recognize the very early signs of cancer is a tough challenge. But we now have highly sophisticated tools which give us real insights into how the immune system recognizes ovarian cancer. OvarianVax could offer the solution.”
How sharing, hearing, and remembering positive stories can help shape our brains for the better
Across cultures and through millennia, human beings have always told stories. Whether it’s a group of boy scouts around a campfire sharing ghost stories or the paleolithic Cro-Magnons etching pictures of bison on cave walls, researchers believe that storytelling has been universal to human beings since the development of language.
But storytelling was more than just a way for our ancestors to pass the time. Researchers believe that storytelling served an important evolutionary purpose, helping humans learn empathy, share important information (such as where predators were or what berries were safe to eat), as well as strengthen social bonds. Quite literally, storytelling has made it possible for the human race to survive.
Today, neuroscientists are discovering that storytelling is just as important now as it was millions of years ago. Particularly in sharing positive stories, humans can more easily form relational bonds, develop a more flexible perspective, and actually grow new brain circuitry that helps us survive. Here’s how.
How sharing stories positively impacts the brain
When human beings share stories, it increases the levels of certain neurochemicals in the brain, neuroscientists have found. In a 2021 study published in Proceedings of the National Academy of Sciences (PNAS), Swedish researchers found that simply hearing a story could make hospitalized children feel better, compared to other hospitalized children who played a riddle game for the same amount of time. In their research, children in the intensive care unit who heard stories for just 30 minutes had higher levels of oxytocin, a hormone that promotes positive feelings and is linked to relaxation, trust, social connectedness, and overall psychological stability. Furthermore, the same children showed lower levels of cortisol, a hormone associated with stress. Afterward, the group of children who heard stories tended to describe their hospital experiences more positively, and even reported lower levels of pain.
Annie Brewster, MD, knows the positive effect of storytelling from personal experience. An assistant professor at Harvard Medical School and the author of The Healing Power of Storytelling: Using Personal Narrative to Navigate Illness, Trauma, and Loss, Brewster started sharing her personal experience with chronic illness after being diagnosed with multiple sclerosis in 2001. In doing so, Brewster says it has enabled her to accept her diagnosis and integrate it into her identity. Brewster believes so much in the power of hearing and sharing stories that in 2013 she founded Health Story Collaborative, a forum for others to share their mental and physical health challenges.“I wanted to hear stories of people who had found ways to move forward in positive ways, in spite of health challenges,” Brewster said. In doing so, Brewster believes people with chronic conditions can “move closer to self-acceptance and self-love.”
While hearing and sharing positive stories has been shown to increase oxytocin and other “feel good” chemicals, simply remembering a positive story has an effect on our brains as well. Mark Hoelterhoff, PhD, a lecturer in clinical psychology at the University of Edinburgh, recalling and “savoring” a positive story, thought, or feedback “begins to create new brain circuitry—a new neural network that’s geared toward looking for the positive,” he says. Over time, other research shows, savoring positive stories or thoughts can literally change the shape of your brain, hard-wiring someone to see things in a more positive light.How stories can change your behavior
In 2009, Paul Zak, PhD, a neuroscientist and professor at Claremont Graduate University, set out to measure how storytelling can actually change human behavior for the better. In his study, Zak wanted to measure the behavioral effects of oxytocin, and did this by showing test subjects two short video clips designed to elicit an emotional response.
In the first video they showed the study participants, a father spoke to the camera about his two-year-old son, Ben, who had been diagnosed with terminal brain cancer. The father told the audience that he struggled to connect with and enjoy Ben, as Ben had only a few months left to live. In the end, the father finds the strength to stay emotionally connected to his son until he dies.
The second video clip, however, was much less emotional. In that clip, the same father and son are shown spending the day at the zoo. Ben is only suggested to have cancer (he is bald from chemotherapy and referred to as a ‘miracle’, but the cancer isn’t mentioned directly). The second story lacked the dramatic narrative arc of the first video.
Zak’s team took blood before and after the participants watched one of the two videos and found that the first story increased the viewers’ cortisol and oxytocin, suggesting that they felt distress over the boy’s diagnosis and empathy toward the boy and his father. The second narrative, however, didn’t increase oxytocin or cortisol at all.
But Zak took the experiment a step further. After the movie clips, his team gave the study participants a chance to share money with a stranger in the lab. The participants who had an increase in cortisol and oxytocin were more likely to donate money generously. The participants who had increased cortisol and oxytocin were also more likely to donate money to a charity that works with children who are ill. Zak also found that the amount of oxytocin that was released was correlated with how much money people felt comfortable giving—in other words, the more oxytocin that was released, the more generous they felt, and the more money they donated.
How storytelling strengthens our bond with others
Sharing, hearing, and remembering stories can be a powerful tool for social change–not only in the way it changes our brain and our behavior, but also because it can positively affect our relationships with other people
Emotional stimulation from telling stories, writes Zak, is the foundation for empathy, and empathy strengthens our relationships with other people. “By knowing someone’s story—where they come from, what they do, and who you might know in common—relationships with strangers are formed.”
But why are these relationships important for humanity? Because human beings can use storytelling to build empathy and form relationships, it enables them to “engage in the kinds of large-scale cooperation that builds massive bridges and sends humans into space,” says Zak.
Storytelling, Zak found, and the oxytocin release that follows, also makes people more sensitive to social cues. This sensitivity not only motivates us to form relationships, but also to engage with other people and offer help, particularly if the other person seems to need help.
But as Zak found in his experiments, the type of storytelling matters when it comes to affecting relationships. Where Zak found that storytelling with a dramatic arc helps release oxytocin and cortisol, enabling people to feel more empathic and generous, other researchers have found that sharing happy stories allows for greater closeness between individuals and speakers. A group of Chinese researchers found that, compared to emotionally-neutral stories, happy stories were more “emotionally contagious.” Test subjects who heard happy stories had greater activation in certain areas of their brains, experienced more significant, positive changes in their mood, and felt a greater sense of closeness between themselves and the speaker.
“This finding suggests that when individuals are happy, they become less self-focused and then feel more intimate with others,” the authors of the study wrote. “Therefore, sharing happiness could strengthen interpersonal bonding.” The researchers went on to say that this could lead to developing better social networks, receiving more social support, and leading more successful social lives.
Since the start of the COVID pandemic, social isolation, loneliness, and resulting mental health issues have only gotten worse. In light of this, it’s safe to say that hearing, sharing, and remembering stories isn’t just something we can do for entertainment. Storytelling has always been central to the human experience, and now more than ever it’s become something crucial for our survival.
Want to know how you can reap the benefits of hearing happy stories? Keep an eye out for Upworthy’s first book, GOOD PEOPLE: Stories from the Best of Humanity, published by National Geographic/Disney, available on September 3, 2024. GOOD PEOPLE is a much-needed trove of life-affirming stories told straight from the heart. Handpicked from Upworthy’s community, these 101 stories speak to the breadth, depth, and beauty of the human experience, reminding us we have a lot more in common than we realize.