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Feeling extra fatigued lately? There are lots of reasons why you may not have the usual pep in your step—from overtraining to underfueling to poor sleep habits that are hampering your recovery. But one less obvious factor worth considering: vitamin B12 deficiency.

Most people are not at risk for B12 deficiency, Selvi Rajagopal, M.D., M.P.H., assistant professor of medicine at The Johns Hopkins University School of Medicine, tells Runner’s World. But it’s more common than you may think, especially among seniors. An estimated 20 percent of people over age 60, and about 6 percent of people younger than that are deficient, according to research. 

To make sure you’re filled up on the vitamin, here’s what to know about its benefits, where to find it, and signs of vitamin B12 deficiency to look for, so you know when to talk to your doctor. 

What to Know About the Importance of Vitamin B12

Vitamin B12 plays an essential role in the growth and development of our nervous system tissues and blood cells, Mark Loafman, M.D., a Chicago-based family physician tells Runner’s World. It’s important for nerve signaling and brain functioning, adds Rajagopal. And it helps break down homocysteine, an amino acid that, if present in high enough amounts, can damage the heart and increase risk of dementia, heart disease, stroke, and osteoporosis, Jen Graham, M.S., R.D.N., a Tallahassee, Florida-based registered dietitian nutritionist with Top Nutrition Coaching, tells Runner’s World. 

Our bodies don’t create B12 on their own, so we need to get it from our diet. It’s typically found in animal foods—like meat, eggs, liver, seafood, and dairy products—as well as fortified cereals. 

Because animal products are a main source of this vitamin, folks who follow a strictly vegan or vegetarian diet and don’t take a B12 supplement are at “significant risk” of deficiency, Loafman says. 

Other susceptible people include those who have conditions that interfere with their ability to absorb B12 from the GI tract, including those with celiac disease (and other GI conditions, like inflammatory bowel disease), pernicious anemia (an autoimmune condition), and people who have had bariatric gastric bypass surgery, Loafman explains. 

Older adults, including those older than age 60, are also at risk of deficiency. That’s because the functioning of your gastric cells naturally declines as you age, decreasing absorption of the vitamin, Loafman adds. 

Low levels of B12 are typically detected through a blood test, Rajagopal explains, which you can request from your doctor or may otherwise be included as a part of a routine physical exam. The recommended dietary allowance for B12 ranges from 0.4 to 2.8 mcg per day and varies based on age, sex, and whether you’re pregnant or breastfeeding, according to the National Institutes of Health.

Now that you know the importance of vitamin B12 and who is most affected by deficiency, let’s dig into the signs you’re not getting enough B12—plus how to remedy low levels. 

Signs of Vitamin B12 Deficiency

Having too little vitamin B12 can cause a host of signs and symptoms. These are directly linked to your “body’s inability to keep up with the production of new blood cells and/or the maintenance and preservation of nervous tissues,” Loafman explains. 

Here’s what to watch out for:

Fatigue, weakness, and lightheadedness. B12 deficiency can lead to megaloblastic anemia, a condition where you don’t have enough red blood cells to carry oxygen to your tissues, Rajagopal says. This, in turn, can cause you to feel tired and weak, she explains. It could also hamper your exercise performance, Loafman adds. In severe cases, the lack of red blood cells can be life threatening. The good news: This type of anemia usually occurs gradually and you’d likely notice signs of it with routine blood testing before developing significant symptoms, Loafman explains.

Numbness and tingling in your limbs. These sensations are often symmetric (meaning, they happen on both sides of the body) and typically involve the legs more than the arms, says Rajagopal. It can also crop up in the fingers and toes, she adds. Numbness and tingling happens because B12 deficiency decreases your ability to maintain nervous system tissue, Loafman explains. This effect on the nervous system can also alter your gait and cause difficulty walking.

Mood changes, trouble concentrating, insomnia, irritability, and possible memory loss. When your body isn’t able to maintain its nervous system tissue, it can cause a host of neuropsychiatric symptoms and cognitive dysfunctions, Loafman explains.

Oral irritation and recurrent ulcers. The mucous membranes in your mouth and throat require rapid new cell growth to keep up with the almost constant turnover of cells, so when these areas aren’t getting the new cells they need due to B12 deficiency, your mouth can bear the brunt of it. In addition to oral irritation and frequent ulcers, you may also notice changes to your tongue, including pain, swelling, tenderness, or pigmentation changes, Rajagopal explains.

Skin changes, like rashes and changes in pigmentation. Again, this is because B12 plays a vital role in cell production, Loafman explains, so when your levels are subpar, you may notice it influences your skin health.

GI symptoms, including nausea and diarrhea. Having low levels of B12 can cause fewer red blood cells to reach your digestive tract, which in turn can trigger symptoms like nausea and diarrhea, Graham explains. In turn, feeling nauseous can lower your appetite, she adds.

Irregular heart rate. With B12 deficiency, your heart may beat faster to make up for the reduced number of red blood cells in the body, Graham says. This is your body’s way of trying to ensure enough oxygen gets circulated to all your organs and bodily systems, she explains. 

How to Know if You Need a Vitamin B12 Supplement

If you’re diagnosed with a vitamin B12 deficiency—which, as mentioned, can be determined from a blood test at your doctor’s office—then it’s wise to up your stores by taking a B12 supplement. 

Additionally, anyone who follows a vegan diet should take a B12 supplement to prevent or correct mild deficiencies that may already be developing, Loafman says. He also recommends supplementation for people whose diets include meat or dairy, but focus more heavily on plant-based foods. Important caveat: There are a lot of health benefits associated with solely and largely plant-based diets, “so no one should feel compelled to consume animal products,” Loafman says. Instead, they should add a B12 supplement to their daily routine.

You may also benefit from a B12 supplement if you have an autoimmune disease that attacks the stomach lining or GI tract (like Crohn’s or celiac disease), have had weight-loss surgery, or are taking heartburn medications that suppress stomach acid, Graham says. Your stomach acid is what extracts B12 from the food you eat, so it’s harder for that to happen if you have less stomach acid, she explains. Older adults may also benefit from supplementation, as they are at greater risk of deficiency. 

Just keep in mind: “There is no guideline or strong evidence base to support vitamin B12 supplementation without proven deficiency,” Rajagopal says. So you may want to first get your levels checked and/or ask your doctor if supplementation is recommended for you before taking a daily pill. 

Loafman, for his part, says patients who are struggling with fatigue or other B12 deficiency symptoms often ask him to prescribe supplements or administer B12 injections, even though they don’t have any risk factors for deficiency and a blood test has confirmed their levels are in the normal range. “Often, they have been told or have heard a B12 shot will boost energy levels or help with weight loss,” Loafman explains. “I wish this were the case, but unfortunately there is no evidence of benefit or improved outcome by taking ‘extra’ B12.” 

To that end, if you’re struggling with fatigue, poor performance and/or mood-slash-cognitive concerns, it’s wise to get evaluated by your doctor, Rajagopal advises. They can confirm whether you do have B12 or other micronutrient deficiencies and help you figure out next best steps. 

How to Choose a Quality Vitamin B12 Supplement

If you’ve determined B12 supplementation is right for you, the next step is to get a high-quality product. 

In the United States, vitamins and supplements are not formally regulated, so it’s best to buy supplements that have been tested by an independent third-party company for quality, safety and purity, Graham says. 

Loafman recommends supplements certified by the United States Pharmacopeia (USP) or National Sanitation Foundation (NSF). “I would not purchase or consume an over-the-counter product that does not have this certification,” he says. You can also get a B12 prescription from your physician, which will assure you are getting a product regulated by the Food and Drug Administration, Rajagopal says. 

Look for supplements containing the natural form of B12 (methylcobalamin) instead of the synthetic (cyanocobalamin) because the latter has the potential to impair kidney function in people with borderline kidney problems, Graham says. 

In some cases, B12 injections are recommended over oral supplements. This might be at the beginning of deficiency treatment to obtain faster results, or because your body’s decreased absorption of B12 is so severe that your levels can’t be fixed with high doses of oral treatment, Loafman explains. 

The dosage for your B12 supplement, and which form is right for you, will depend on factors including your specific level of deficiency. Again, this is why it’s worthwhile to first check in with your doctor. 

Some victories are measured by finish times. Others are defined by the obstacles overcome simply to reach the starting line.

For American Paralympic swimmer Ali Truwit, completing the New York City Marathon represented far more than covering 26.2 miles. It was the culmination of an extraordinary journey of survival, resilience, and unwavering determination that began with a life-altering shark attack just two years earlier.

On a crisp November morning in 2025, Truwit crossed the iconic finish line wearing a carbon-fibre running blade, fulfilling a promise she had made while recovering in a hospital bed after losing her lower left leg. The emotional milestone marked another remarkable chapter in one of the most inspiring comeback stories in modern sport.

The road to that unforgettable finish began only days after Truwit celebrated a major personal achievement. In May 2023, she completed her first marathon in Copenhagen alongside her mother. Just ten days later, while enjoying a graduation trip to Turks and Caicos with former Yale swimming teammate Sophie Pilkinton, tragedy struck.

While the pair were snorkelling, a shark attacked Truwit, severely injuring her left leg. Displaying remarkable courage, the two swam approximately 55 metres back to their boat, where Pilkinton—then a medical student—quickly applied a tourniquet that stopped the bleeding and ultimately saved Truwit's life.

Doctors were forced to amputate her lower left leg on her 23rd birthday.

Even in the darkest moments of recovery, Truwit's determination never disappeared. Reflecting on having recently completed her first marathon, she joked with one of the first responders that at least she had managed to run a marathon before the attack. The responder's simple but powerful reply would remain with her throughout rehabilitation: "You'll run another one."

Those words became a source of hope during the long and demanding road back.

Only weeks after surgery, Truwit began learning to walk on a prosthetic limb before gradually returning to the swimming pool. The process was anything but straightforward. The water that had once been her sanctuary became a source of painful memories, yet she refused to allow fear to define her future.

Her relentless work ethic soon produced extraordinary results.

Less than 16 months after the attack, Truwit represented the United States at the Paris 2024 Paralympic Games, producing a sensational performance to claim both silver and bronze medals. Standing on the Paralympic podium was a powerful reminder of how far she had come in such a short period, and she dedicated those achievements to everyone who had helped save her life.

Still, another dream remained unfinished.

The New York City Marathon carried deep personal significance. It was not merely another endurance event but a symbolic return to the city where her life had changed forever. On November 2, 2025, she lined up in Staten Island accompanied by 13 family members and close friends, all proudly representing her nonprofit foundation, Stronger Than You Think. Among them was Pilkinton, the friend whose quick thinking had preserved her life on that unforgettable day in the Caribbean.

Together, they covered every mile of the marathon before celebrating an emotional finish that Truwit later described as being "over the moon."

Completing a marathon on a carbon-fibre running blade presents challenges far beyond those faced by able-bodied runners. The prosthetic demands greater strength from the hips, core, and remaining leg while requiring exceptional balance, coordination, and endurance. Truwit's preparation combined months of disciplined training, patience, and mental resilience as she effectively taught herself how to run again.

Her story extends well beyond medals and marathon finishes.

Inspired by her own recovery, Truwit founded Stronger Than You Think, a nonprofit organisation dedicated to helping individuals overcome physical and financial barriers following limb loss. Recognising that sports prosthetics can cost tens of thousands of dollars and are often not covered by insurance, the foundation provides financial assistance for prosthetic devices, supports water-safety education, and promotes opportunities within Paralympic sport.

The organisation has already helped provide more than 11 prosthetic limbs, delivered nearly $200,000 in direct support, and funded over 4,000 hours of water-safety lessons benefiting more than 700 young people.

Throughout her journey, Truwit has remained refreshingly honest about the emotional challenges that continue to accompany recovery. She has openly acknowledged that healing is an ongoing process and that grief can still come in waves. Rather than portraying an effortless comeback, she has demonstrated that resilience is built through persistence, even on the hardest days.

Her remarkable transformation resonates far beyond elite sport. While few people will ever experience the trauma she endured, countless runners and athletes understand the frustration of injury, disappointment, or rebuilding after adversity. Truwit's journey serves as a powerful reminder that recovery is rarely linear and that courage is often measured by the willingness to keep moving forward despite uncertainty.

Now looking ahead to the Los Angeles 2028 Paralympic Games, Truwit continues to redefine what is possible. She is no longer known simply as the swimmer who survived a shark attack. She has become a Paralympic medallist, marathon finisher, advocate, and symbol of resilience whose story continues to inspire athletes around the world.

Her journey proves that while life can change in an instant, so too can the strength of the human spirit. Sometimes the greatest triumph is not returning to the person you once were, but discovering someone even stronger than you ever imagined possible.

Sprint and hurdles superstar Sydney McLaughlin-Levrone has entered an exciting new chapter in her remarkable life, welcoming her first child with husband Andre Levrone. The four-time Olympic champion and women's 400m hurdles world record holder announced the birth of their daughter, Savannah Michelle Levrone, who was born on Sunday, July 12, 2026.

The couple shared the joyful news with an emotional message celebrating the arrival of their daughter and expressing gratitude to everyone who supported them throughout the pregnancy. Sydney described Savannah as "our blessing and our joy," while expressing excitement and faith for the future that lies ahead for their growing family.

The announcement marks a deeply personal milestone for one of the most accomplished athletes of her generation. Renowned for redefining the women's 400m hurdles through a succession of record-breaking performances, McLaughlin-Levrone now embraces a new role beyond the track as a mother.

The timing of the announcement adds another layer of significance. Just days earlier, Sydney reflected on the 10th anniversary of qualifying for her first Olympic Games at only 16 years old—a breakthrough that launched one of the most decorated careers in modern athletics. Ten years later, her journey has come full circle with another life-changing milestone, underscoring that her greatest moments continue to extend beyond sporting success.

The arrival of Savannah Michelle Levrone has been met with an outpouring of congratulations from athletes, fans, and the wider sporting community, who have celebrated the couple as they begin this new chapter together. As Sydney McLaughlin-Levrone steps into motherhood, the athletics world will undoubtedly continue to follow her inspiring journey—both on and off the track.

Ethiopia's Tsige Gebreselama produced one of the standout road running performances of the season on Sunday, storming to victory at the prestigious Boilermaker Road Race 15K in Utica, New York, with a sensational course record of 47:29.

From the opening kilometers, Gebreselama controlled the race with remarkable composure and precision, maintaining a relentless pace that ultimately erased the previous course record and secured one of the fastest performances ever recorded on the historic course. Her commanding display further reinforced her reputation as one of the world's leading road and distance runners.

The Ethiopian celebration continued as Melknat Wudu crossed the finish line in second place in 47:44, completing a dominant one-two finish for her country. Kenya's Priscah Cherono claimed third in 48:14 after a determined effort, rounding out a world-class podium in a race featuring some of the finest distance runners on the international circuit.

The battle behind the podium remained fiercely competitive. Kenya's Everlyn Kemboi finished fourth in 48:28, narrowly ahead of compatriot Selah Busienei, who clocked 48:31 for fifth. Ethiopia's Netsanet Desta and Alem Nigus Tsadik followed in sixth and seventh respectively, while Kenya's Mercy Cherono secured eighth place.

American athletes also delivered encouraging performances on home roads. Veteran Stephanie Bruce finished ninth in 50:40, with Jackie Gaughan completing the top ten in 51:02 to cap a strong showing for the host nation.

Boilermaker Road Race 15K – Women's Top 10 Results

1. Tsige Gebreselama (Ethiopia) – 47:29 (Course Record)

2. Melknat Wudu (Ethiopia) – 47:44

3. Priscah Cherono (Kenya) – 48:14

4. Everlyn Kemboi (Kenya) – 48:28

5. Selah Busienei (Kenya) – 48:31

6. Netsanet Desta (Ethiopia) – 48:46

7. Alem Nigus Tsadik (Ethiopia) – 48:48

8. Mercy Cherono (Kenya) – 50:23

9. Stephanie Bruce (United States) – 50:40

10. Jackie Gaughan (United States) – 51:02

The women's race combined exceptional depth with remarkable speed, as several athletes broke the 49-minute barrier in a contest that showcased the global strength of elite road running. Gebreselama's record-breaking run now stands as a new benchmark in the rich history of the Boilermaker 15K, adding another memorable chapter to one of the United States' most celebrated road races.

Kenya's Alex Matata delivered a sensational performance to claim the men's title at the prestigious Boilermaker Road Race 15K in Utica, New York, producing a dominant run that underlined his growing reputation as one of the world's finest road racers.

Matata surged to victory in an outstanding time of 42:24, mastering the demanding course with a display of strength, speed, and tactical brilliance. His commanding performance secured a memorable triumph in one of the United States' most celebrated road races, adding another significant international victory to his career.

Kenya's success was further highlighted by Kiprono Sitonik, who produced an equally impressive run to finish second in 42:53, completing a remarkable one-two finish for the East African nation. South Africa's Adam Lipschitz rounded out the podium after clocking 43:14 to claim third place following a determined effort.

The race featured a highly competitive international field, with American athletes Reid Buchanan and Hillary Bor finishing fourth and fifth respectively, while another Kenyan, Victor Shitsama, added to his country's strong showing by taking sixth place.

Matata's victory once again showcased Kenya's enduring strength in global road racing, as its athletes continued to dominate major international competitions through exceptional endurance, tactical awareness, and relentless finishing speed. His performance in Utica not only thrilled the spectators lining the streets but also reinforced the depth of Kenyan distance running on the world stage.

Men's Top 10 Results – Boilermaker Road Race 15K

1. Alex Matata (Kenya) – 42:24

2. Kiprono Sitonik (Kenya) – 42:53

3. Adam Lipschitz (South Africa) – 43:14

4. Reid Buchanan (United States) – 43:38

5. Hillary Bor (United States) – 43:40

6. Victor Shitsama (Kenya) – 44:02

7. Futsum Zienasellassie (United States) – 44:32

8. Charlie Sweeney (United States) – 44:37

9. Sam Lawler (United States) – 44:54

10. Tyler Berg (United States) – 45:08

With another major road racing title added to his résumé, Alex Matata continued his impressive 2026 campaign while reinforcing his status as one of the leading names on the international road racing circuit. The Boilermaker 15K once again delivered a high-quality contest, with athletes from across the globe producing memorable performances in one of the United States' most prestigious road races.

Eliud Kipchoge's remarkable World Tour continued on Brazilian soil as the Kenyan marathon icon completed the New Balance 42K Porto Alegre Marathon, crossing the finish line in 2:18:39 to place 12th overall during the second stop of his ambitious seven-continent global running tour.

Competing against a strong international field, the two-time Olympic marathon champion displayed the resilience and determination that have defined his legendary career. While the result was not among the victories that have made him one of the greatest marathon runners in history, Kipchoge once again demonstrated the unwavering commitment that continues to inspire athletes and fans across the globe.

Morocco's Zineddine Ouria claimed victory in a superb 2:08:49, with Kipchoge finishing 9 minutes and 50 seconds behind the race winner after navigating the demanding course in Porto Alegre.

Kipchoge began the race with controlled and confident pacing, reaching 5km in 15:34 before passing the halfway mark in 1:05:07. As the race entered its decisive stages, the pace gradually slowed, but the veteran marathoner pressed on with characteristic determination, completing the 42.195-kilometre challenge in 2:18:39.

For many, the story will be told through the finishing position. But for those who truly understand greatness, this journey is about far more than medals, records, or podium finishes. Kipchoge's World Tour is a celebration of the sport itself—an opportunity to connect with runners across every continent, inspire the next generation, and continue living by the philosophy that has become synonymous with his career: "No Human Is Limited."

The Brazilian appearance also carried added significance, coming shortly after Kipchoge was permanently honoured in Porto Alegre with his footprints unveiled at the entrance of Parque Harmonia—a lasting tribute to his extraordinary impact on distance running and his enduring legacy in the sport.

Once a champion. Forever an inspiration. Legends do not stop inspiring when the victories become fewer; they inspire because they never stop showing up. Through every stride, every finish line, and every challenge embraced, Kipchoge continues to prove that true greatness is measured not only by what an athlete wins, but by the lives they touch along the way.

With the second stop of his World Tour now complete, Kipchoge will turn his attention to the next chapter of his global adventure when he lines up at the Melbourne Marathon in Australia this October. Wherever he races, millions will once again follow the journey of a man whose legacy extends far beyond the stopwatch.