There's a direct relationship between vitamin B12 and the mineral iron — and it has to do with making sure your body is continuously replenished with fresh oxygen. That's a pretty important job, if you ask us.
"For starters, vitamin B12 plays a role in the normal functioning of the nervous system and brain," Erin Palinski-Wade, RD and author of 2-Day Diabetes Diet, tells LIVESTRONG.com. "It also helps in the formation of red blood cells in the body." She further explains that iron helps to carry oxygen from the lungs to every cell in the body. "A deficiency in iron can result in poor oxygenation of the body's cells, while a deficiency in B12 can result in low levels of circulating red blood cells."
Medical researchers continue to find additional health benefits for these vital nutrients. A 2018 study presented at the Society for Endocrinology's annual conference in Glasgow, Scotland states that patients being treated for type 2 diabetes should be routinely checked for a vitamin B12 deficiency since lacking in this water-soluble vitamin can increase the risk of developing irreversible, painful and potentially disabling nerve damage.
And after studying nearly 3,000 women over a ten-year period, researchers reported that nonheme iron, which comes from plant sources and supplements rather than animal sources, may be associated with a lower risk of PMS, per a February 2013 study in the American Journal of Epidemiology.
Even though this essential vitamin and mineral combo can be obtained in supplement form, a number of common kitchen staples contain both vitamin B12 and iron.
"This seafood is often overlooked, but it is actually a rich source of both B12 and iron," says Palinski-Wade. In fact, a 1-cup serving of these small, oily fish offers a whopping 555 percent your daily value (DV) of vitamin B12 and 24 percent of your DV of iron. "In addition, sardines are a good source of the heart-healthy omega-3 fatty acids that most of us don't get enough of in our diets."
Another bonus: A diet comprised of wild sardines can have a lower environmental impact than vegan or vegetarian diets, a June 2018 study published in the journal Frontiers in Ecology and the Environment states. Since canned sardines tend to contain high amounts of sodium, Palinski-Wade suggests choosing either low-sodium or sodium-free varieties.
Good news for red meat lovers! A 6-ounce serving of steak is packed with 533 percent of your DV of vitamin B12 and 52 percent DV of iron.
The Mayo Clinic advises limiting how much meat you eat, along with selecting a healthier lean cut — which is labeled as either round, chuck, sirloin or tenderloin. "When shopping or ordering red meat, opt for grass-fed, lean cuts over higher fat cuts, like prime rib," Palinski-Wade says.
Many versions of this breakfast staple provide a solid source of both nutrients, which is welcoming news for those who follow a vegan or vegetarian eating style, explains Palinski-Wade. For example, 1 cup of oat-bran-based cereal contains 63 percent of B12's DV, along with 8 percent DV of iron.
Perhaps you'd want to start your day with a bowl of fortified oatmeal: An October 2016 study published in the British Journal of Nutrition found it can reduce three markers associated with developing heart disease. "However, just make sure to choose whole-grain varieties that are low in added sugar," says Palinski-Wade.
"Along with packing in B12 and iron, eggs are such a versatile protein option that can be easily added to most meals," Palinski-Wade tells us. Two large eggs provide 37 percent of your DV of vitamin B12 as well as 10 percent of your DV of iron.
While the egg debate is ongoing, one study showed that eating 12 or more eggs per week did not increase the risk of heart disease in people with either prediabetes or type 2 diabetes, according to May 2018 research in The American Journal of Clinical Nutrition.
Plus, a May 2019 study analyzed the eating habits of 1,950 men between the ages of 42 and 60 for a total of 21 years and found that consuming one egg per day was not associated with a higher risk of stroke, per research published in the American Journal of Clinical Nutrition.
Read more: 7 Reasons to Crack an Egg for Breakfast
"Not only does eating shellfish provide both iron and B12 to your diet but enjoying more seafood can be beneficial for your heart," says Palinski-Wade. One raw oyster, for example, is loaded with vitamin B12 — 333 percent of your DV — while also containing a moderate amount of iron with 14 percent of your DV.
Oysters are also chock-full of zinc with 76 percent of your DV per each medium oyster. Zinc is an essential nutrient that boosts the immune system and promotes wound healing. "Aim for wild-caught fish versus farm-raised, since the latter may contain higher levels of contaminants," Palinski-Wade adds.
- Society for Endocrinology: "Routine Vitamin B12 Screening May Prevent Irreversible Nerve Damage in Type-2 Diabetes"
- American Journal of Epidemology: "Intake of Selected Minerals and Risk of Premenstrual Syndrome"
- MyFoodData: "Canned Sardines"
- FDA.gov: "% Daily Value"
- Frontiers in Ecology and the Environment: "The Environmental Cost of Animal Source Foods"
- MyFoodData.com: "Skirt Steak"
- MyFoodData: "Oat Bran Flakes Health Valley"
- British Journal of Nutrition: "The Effect of Oat Β-glucan on LDL-cholesterol, Non-HDL-Cholesterol and Apob for CVD Risk Reduction: a Systematic Review and Meta-Analysis of Randomised-Controlled Trials"
- MyFoodData: "Eggs (Raw)"
- American Journal of Clinical Nutrition: "Effect of a High-Egg Diet on Cardiometabolic Risk Factors in People With Type 2 Diabetes: the Diabetes and Egg (DIABEGG) Study—Randomized Weight-loss and Follow-up Phase"
- American Journal of Clinical Nutrition: "Egg Consumption, Cholesterol Intake, and Risk of Incident Stroke in Men: the Kuopio Ischaemic Heart Disease Risk Factor Study"
- MyFoodData: "Raw Pacific Oysters"
- Mayo Clinic: "How Meat and Poultry Fit in Your Healthy Diet"
- TeensHealth: Becoming a Vegetarian