Only 12% of Americans get the recommended amount of vegetables, while 15% eat the minimum recommended amount of fruit, and a mere 1% get the amount of whole grains needed for a healthy diet, according to a study in the journal Circulation.

And a recent survey by Purdue University determined that almost 46% have a markedly unhealthy diet.

Unfortunately, few people know the signs of nutritional deficiencies or how to correct them. So here's a quick rundown:

• Tingling hands and/or feet, changes in the color or texture of your tongue, and mood swings may be signs of vitamin B6, B12, thiamin, riboflavin, and/or folate deficiency. B12 deficiency can also cause erectile dysfunction, urinary and fecal incontinence, and lack of balance.

• Dermatitis and rashes may indicate a lack of vitamins A, B2, B3, and B6. Hair loss or brittle nails can signal that you need more vitamin B7.

• Fatigue can come from a mix of deficiencies, including B vitamins, vitamin C, magnesium, zinc, and iron.

If you have symptoms of poor nutrition (or know you aren't eating a healthy diet), ask your doctor to test the nutrient levels in your blood. If you're deficient, work together to design a diet that supplies necessary nutrients and to determine what supplements can give you an immediate boost.

For more information on how to keep your body healthy and as young as possible, check out "YOU On A Diet, revised edition."