If you pay close enough attention, your body will let you know when something’s amiss. Case in point: symptoms of a vitamin deficiency. Vitamin B12 is vital for many functions throughout your body. It produces adrenal hormones, metabolizes folate, fat and carbohydrates, forms red blood cells, aids in iron absorption, helps ensure proper circulation, promotes reproductive health and supports nervous system function, among other things. Clearly, B12 is important. Yet people aren’t getting enough.

According to the USDA, nearly 40% of Americans have marginal B12 status and 9% are deficient. Vitamin B12 insufficiency and deficiency increase your risk of serious health problems, many of which mimic more serious neurological diseases and can easily lead to misdiagnosis and improper treatment.

Some people have a greater risk than others for vitamin or mineral deficiencies, but in this case vegans and vegetarians are at particular risk because B12 is derived from animal products. Additionally, older adults and people with gastrointestinal and malabsorption issues are also at risk.

A B12 deficiency can cause a variety of symptoms, and some of them can show up in your mouth and/or in your eyes. Signs of a B12 deficiency to look for in your mouth include: a red, swollen, “beefy” tongue with fewer papillae bumps containing taste bloods, and mouth sores or ulcers. Signs of a B12 deficiency to look for in your eyes include: blurry or double vision, or shadows in your field of vision, caused by optic nerve damage.

Other symptoms of a B12 deficiency include: a numb, tingly, “pins and needles” sensation in your hands, legs or feet, jaundice, dizziness and memory loss.

Animal products — whether dairy, poultry or meat — are excellent sources of vitamin B12. If you suspect you're not getting enough B12, here are some foods you should consider adding to your diet (make sure that you're getting these from high-quality sources to keep yourself safe from chemicals and other harmful materials used in conventional farms):

• Sardines
• Grass fed beef
• Pasture-raised organic eggs
• Mussels

• Raw, organic grass fed milk
• Organic free-range chicken
• Wild Alaskan salmon
• Herring