<strong>body cue:</strong> 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.
<strong>body cue:</strong> 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.
<strong>body cue:</strong> red or white acnelike 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."
<strong>body cue:</strong> 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.
<strong>body cue:</strong> 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.