When your body is trying to tell you something—for example, that you're skimping on critical vitamins—it may go to some strange lengths. 
"With today's diet of processed foods, it's easy to become vitamin-deficient, either by not eating enough of the right foods or not absorbing them properly due to digestive issues," says Dr. Susan Blum, the founder of the Blum Center for Health and the author of the new book The Immune System Recovery Plan. "You may not get a disease, but you can end up with impaired functioning, because vitamins are cofactors for all the biochemical reactions in the body. We need them in order to function properly." 
That impaired functioning can sometimes manifest in mysterious ways.
Here are five unusual warning signs that you may be vitamin-deficient. The good news: Most are fixable with dietary tweaks—all the more reason to make nutrition a top priority. But if food cures don't work, be sure to check in with your doctor.
Body Cue No. 1: Cracks at the corners of your mouth.
The Deficiency: Iron, zinc, and B vitamins like niacin (B3), riboflavin (B2), and B12. "It's common if you're a vegetarian to not get enough iron, zinc, and B12," Blum says. Ditto if you're skimping on essential immunity-building protein due to dieting.
The Fix: Eat more poultry, salmon, tuna, eggs, oysters, clams, sun-dried tomatoes, Swiss chard, tahini, peanuts, and legumes like lentils. Iron absorption is enhanced by vitamin C, which also helps fight infection, so combine these foods with veggies like broccoli, red bell peppers, kale, and cauliflower.
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Body Cue No. 2: A red, scaly rash on your face (and sometimes elsewhere) and hair loss.
The Deficiency: Biotin (B7), known as the hair vitamin. While your body stores fat-soluble vitamins (A, D, E, K), it doesn't store most B vitamins, which are water-soluble. Body builders take note: Eating raw eggs makes you vulnerable, because a protein in raw eggs called avidin inhibits the body's ability to absorb biotin.
The Fix: Reach for more cooked eggs (cooking deactivates avidin), salmon, avocados, mushrooms, cauliflower, soybeans, nuts, raspberries, and bananas.
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Body Cue No. 3: Red or white acne-like bumps, typically on the cheeks, arms, thighs, and butt.
The Deficiency: Essential fatty acids and vitamins A and D.
The Fix: Skimp on saturated fat and trans fats, which you should be doing anyway, and increase healthy fats. Focus on adding more salmon and sardines, nuts like walnuts and almonds, and seeds like ground flax, hemp, and chia. For vitamin A, pile on leafy greens and colorful veggies like carrots, sweet potatoes, and red bell peppers. 
"This provides beta carotene, a precursor to vitamin A, which your body will use to make vitamin A," Blum says. "For vitamin D, though, I recommend a supplement—2,000 IU a day in one that also contains vitamins A and K, which help with D absorption."
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Body Cue No. 4: Tingling, prickling, and numbness in hands, feet, or elsewhere.
The Deficiency: B vitamins like folate (B9), B6, and B12. "It's a problem directly related to the peripheral nerves and where they end in the skin," says Blum, noting that these symptoms can be combined with anxiety, depression, anemia, fatigue, and hormone imbalances.
The Fix: Seek out spinach, asparagus, beets, beans (pinto, black, kidney, lima), eggs, octopus, mussels, clams, oysters, and poultry.
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Body Cue No. 5: Crazy muscle cramps in the form of stabbing pains in toes, calves, arches of feet, and backs of legs.
The Deficiency: Magnesium, calcium, and potassium. "If it's happening frequently, it's a tip-off that you're lacking in these," Blum says. And if you're training hard, you can lose more minerals (and water-soluble B vitamins) through heavy sweating.
The Fix: Eat more bananas, almonds, hazelnuts, squash, cherries, apples, grapefruit, broccoli, bok choy, and dark leafy greens like kale, spinach, and dandelion.