Running News Daily

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. 

The prospect of seeing one of athletics' biggest stars back on the track is growing stronger, with Jakob Ingebrigtsen reportedly targeting a return to competition later this summer following his recovery from Achilles tendon surgery.

According to comments made by his agent, Daniel Wessfeldt, in an interview with Norwegian media, the double Olympic champion could make his long-awaited comeback at one of three major European meetings in July. The leading options under consideration are the Monaco Diamond League on July 10, the Hungarian Athletics Grand Prix on July 14, and the London Diamond League on July 18.

For athletics fans, the possibility of Ingebrigtsen lining up in London would add another layer of excitement to an already highly anticipated Diamond League meeting. The Norwegian middle-distance sensation has become one of the sport's most dominant figures in recent years, collecting Olympic, world and European titles while consistently rewriting record books.

His 2026 campaign was put on hold after he underwent surgery on his Achilles tendon earlier this year, forcing him to focus on rehabilitation rather than competition. Since then, questions have surrounded when the 24-year-old would be ready to return to racing.

The latest update suggests that decision will largely depend on how his training progresses over the coming weeks. If recovery continues according to plan, July could mark the beginning of his return to elite competition ahead of the latter stages of the season.

A comeback at either Monaco, Budapest or London would immediately place Ingebrigtsen back among the sport's biggest storylines. Each meeting is renowned for producing world-class performances, and any appearance by the Norwegian would attract significant attention from fans eager to see how quickly he can regain top form after his injury setback.

While no final decision has been confirmed, the signs are increasingly positive. After months away from competition, Jakob Ingebrigtsen appears to be edging closer to a return, with London's Diamond League meeting emerging as one of the most intriguing possibilities on his road back to the track.

Should his recovery continue smoothly, athletics could soon welcome back one of its brightest and most influential stars.

What should have been the defining moment of Emad Bashir-Mohammed's young running career instead turned into one of the most talked-about controversies in American road racing this year.

The 23-year-old crossed the finish line first in the men's citizen's race at the prestigious Bolder Boulder 10K on Memorial Day in Colorado, stopping the clock at an impressive 29:50. His performance was not only a commanding victory but also one of the fastest winning times ever recorded in the event's long and celebrated history. Bashir-Mohammed finished eight seconds clear of his nearest challenger and appeared to have secured a breakthrough triumph.

For nearly two hours, he was the undisputed winner.

Then everything changed.

Race officials announced that Bashir-Mohammed had been disqualified after determining that he had started in the wrong wave. According to Bolder Boulder regulations, he had been assigned to the AA wave but lined up with the faster A wave, which began earlier. Event rules allow runners to move backward into a slower wave, but prohibit athletes from advancing into a faster one.

As a result, Bashir-Mohammed's victory was erased from the record books.

The citizen's title was subsequently awarded to Nickolas Scudder, who crossed the line second in 29:58. The promotion handed Scudder back-to-back citizen's race victories, while Bashir-Mohammed was left to grapple with the disappointment of losing a win he believed he had earned on the road.

The disqualification has since ignited widespread debate across the running community.

Bashir-Mohammed maintains that he did not intentionally violate the rules. He claims that after collecting his AA bib, he spoke with race personnel and was permitted to start with the A wave after presenting evidence of his recent performances. In a statement shared after the race, he expressed frustration over the decision, arguing that his goal was simply to compete against the strongest field available and produce the fastest time possible.

Race organizers, however, stood firmly behind their ruling. Officials stated that wave-assignment regulations are clearly communicated in pre-race information and reiterated during packet collection. They also noted that hundreds of participants are disqualified each year for moving into faster start groups, emphasizing that consistent enforcement is necessary to maintain fairness for all competitors.

The incident has divided opinion among runners and fans alike. Some believe the rules must be applied equally regardless of an athlete's finishing position, arguing that wave assignments are a fundamental part of race organization. Others feel the punishment is harsh, particularly if Bashir-Mohammed genuinely received approval to move up before the start.

What remains undisputed is the quality of his performance. On the roads of Boulder, Bashir-Mohammed demonstrated the fitness and speed required to outrun the field by a significant margin. Yet in road racing, crossing the finish line first is only part of the equation. Compliance with race regulations carries equal weight.

For Bashir-Mohammed, the day will be remembered as a painful lesson in the fine margins that can define elite competition. A remarkable run delivered a memorable victory, but a dispute over wave placement ultimately overshadowed the achievement, leaving behind a controversy that continues to fuel discussion throughout the running world.

A fast race, a costly administrative error, and a debate that may linger long after the finish-line tape has been packed away.

The men's 100 metres at the 2026 Rome Diamond League is shaping up to be one of the most anticipated sprint races of the season, with an exceptional field featuring some of the fastest men in the world.

Scheduled for Thursday, June 4, at the iconic Stadio Olimpico in Rome, the race will bring together reigning stars, established champions and emerging talents in a contest that promises fireworks from the moment the gun goes off.

Kenya's Ferdinand Omanyala headlines a world-class lineup that includes American sprint sensation Noah Lyles, Botswana's Olympic champion Letsile Tebogo, Jamaica's explosive Ackeem Blake, South Africa's ever-consistent Akani Simbine and Italy's hometown hero Lamont Marcell Jacobs. With personal bests ranging from 9.77 to 9.97 seconds, the field is packed with athletes capable of producing something special on the Diamond League stage.

Omanyala, the African record holder with a blistering personal best of 9.77 seconds, arrives in Rome eager to continue his strong early-season form and prove he can challenge the very best on the global circuit. The Kenyan star has built a reputation as one of the fastest starters in world sprinting and will be looking to make a statement against an elite field.

Standing in his way is world champion Noah Lyles, whose personal best of 9.79 seconds places him among the fastest athletes in history. The American remains one of the sport's biggest attractions and will be determined to add another Diamond League victory to his impressive résumé.

The race also marks a major test for Olympic champion Letsile Tebogo. The Botswanan star has rapidly become one of athletics' most exciting talents, while Ackeem Blake continues to establish himself as a serious contender on the international sprint scene.

Adding further intrigue is the presence of Italy's Lamont Marcell Jacobs. Competing on home soil, the Tokyo Olympic champion will enjoy passionate local support as he seeks to deliver a memorable performance in front of the Roman crowd.

South Africa's Akani Simbine, Cameroon's Emmanuel Eseme, Great Britain's Jeremiah Azu and rising American talent Jordan Anthony complete a field that boasts remarkable depth and quality.

Men's 100m Entry List – Rome Diamond League 2026

Ferdinand Omanyala (Kenya) – PB: 9.77

Noah Lyles (USA) – PB: 9.79

Lamont Marcell Jacobs (Italy) – PB: 9.80

Akani Simbine (South Africa) – PB: 9.82

Letsile Tebogo (Botswana) – PB: 9.86

Ackeem Blake (Jamaica) – PB: 9.88

Jordan Anthony (USA) – PB: 9.91

Emmanuel Eseme (Cameroon) – PB: 9.96

Jeremiah Azu (Great Britain) – PB: 9.97

With multiple national record holders, global champions and Olympic medal contenders sharing the same start line, the Rome Diamond League men's 100m could deliver one of the fastest races of the year. For sprint fans around the world, all eyes will be on Rome as a stellar cast battles for supremacy over athletics' blue-riband distance.

Audrey Werro announced her arrival as one of the early stars of the 2026 outdoor season with a commanding victory in the women’s 800 metres at the Rabat Diamond League, producing a performance that exceeded even her own expectations.

The Swiss middle-distance talent surged to victory in a brilliant 1:56.56, breaking the meeting record and delivering one of the fastest times recorded worldwide this season. In a race packed with quality, Werro displayed exceptional composure, confidence, and finishing strength to separate herself from the field and stamp her authority on the event.

What made the performance even more remarkable was the athlete's surprise at the level she had already reached so early in the campaign.

"I was not expecting such a strong start to the season," Werro admitted after the race.

The race unfolded at a relentless pace, but Werro remained perfectly positioned throughout. As the athletes approached the bell lap, she glanced at the clock and immediately sensed something special was within reach.

"When I saw the time at the bell, I felt really confident," she said. "I'm really happy with the Meeting Record and looking forward to the rest of the season."

Her confidence proved justified. Maintaining her rhythm over the final 400 metres, Werro powered down the home straight to secure the victory and rewrite the Rabat meeting record books in the process.

The performance sends an early warning to her rivals ahead of a season that promises major championships and high-profile Diamond League battles. Beyond the record-breaking time, Werro's display highlighted her growing maturity as a racer, combining tactical awareness with impressive speed and endurance.

With the outdoor season only beginning, the 1:56.56 clocking suggests that even faster times could be on the horizon. If Rabat is any indication, Audrey Werro may be poised for the biggest season of her career.

Her emphatic victory in Morocco was more than just another Diamond League win—it was a statement of intent from an athlete determined to challenge the world's best throughout 2026.

The city of Boston is set to welcome back one of its most celebrated champions as Kenya’s Sharon Lokedi headlines a world-class field for the 2026 B.A.A. 10K presented by Mass General Brigham Cancer Institute on June 21.

Fresh from another remarkable victory at the Boston Marathon in April, Lokedi returns to the streets of Boston and Cambridge carrying both momentum and confidence as she aims to defend the title she captured in dominant fashion last year.

The two-time Boston Marathon champion has developed a special connection with the historic race city. In 2025, she produced a course-record performance of 2:17:22 to win the Boston Marathon before returning this year to claim another victory in 2:18:51, the second-fastest winning time in the event’s storied history. Her success has cemented her status as one of the premier road runners in the world.

Lokedi will be making her first competitive appearance since her marathon triumph and arrives as the reigning B.A.A. 10K champion after clocking 31:39 over the challenging 6.2-mile course in 2025.

“Boston has become a very special place for me,” Lokedi said ahead of the race. “The atmosphere created by the fans and the community is unlike anywhere else. I’m excited to return and give everything I have to defend my title.”

The women’s race promises to be highly competitive. American Olympian Rachel Smith, who finished second at the Boston 5K in April, leads the domestic challenge. Kenya’s strong contingent includes African 10,000m champion Gladys Kwamboka, former B.A.A. 10K runner-up Stacy Ndiwa, and experienced road racer Viola Cheptoo. British Olympian Jessica Warner-Judd adds further international depth to a field packed with proven performers.

The men’s race is equally impressive, featuring elite athletes from 13 nations.

Ethiopia’s Dawit Seare enters as one of the leading contenders after capturing the 2025 Boston 5K title and bringing the fastest 10K personal best in the field at 27:21. Kenya will be represented by an accomplished group led by Alexander Mutiso, winner of the 2024 London Marathon and runner-up at last year’s New York City Marathon.

Patrick Kiprop also arrives in outstanding form after securing victory at the prestigious BolderBoulder 10K on Memorial Day, while Alex Masai returns looking to continue his strong record in Boston. Masai recently finished ninth at the Boston Marathon and has earned three top-ten finishes at the B.A.A. 10K.

Among the international stars making their mark is South Africa’s Adriaan Wildschutt, who makes his race debut after an impressive season highlighted by victory at the NYC Half Marathon in 59:30. Ethiopia’s Olympic bronze medallist Hagos Gebrhiwet adds further quality to the field, bringing a wealth of championship experience and previous success in Boston.

Canadian national 10K champion Andrew Alexander, two-time U.S. Olympian Hillary Bor, marathon standout Ryan Ford, and reigning USA 25K champion Andrew Colley complete a field stacked with talent and depth.

With defending champions, Olympic finalists, national champions and rising stars all converging on Boston, the 2026 B.A.A. 10K is shaping up to be one of the most competitive editions in recent memory. For Sharon Lokedi, however, the mission is simple: return to the city where she has repeatedly excelled and add another memorable chapter to her growing Boston legacy.