Here are five key nutrients that most of us are not getting enough of from our diet. One of them is likely not a surprise to you. In fact I call it the "vitamin du jour" - the one everyone is talking about - Vitamin D. The others are Magnesium, Vitamin B12, Potassium, and Iodine.

Vitamin D is required for healthy bones and teeth. It allows for absorption of Calcium and Phosphorus in the intestine. It maintains a stable nervous system and normal heart action. A recent study in Circulation found that people deficient in Vitamin D were up to 80% more likely to suffer a heart attack or stroke. The belief is that Vitamin D may reduce arterial inflammation.

Lack of Vitamin D may cause osteoporosis or softening of bones, rickets, tooth decay, poor healing of fractures, lack of vigor, muscular weakness, inadequate absorption of calcium, or retention of phosphorus in the kidneys.

Vitamin D is created in the body from the Sun's ultraviolet B rays (yes those very rays that we are protecting our self from with sunscreen). Vitamin D is a fat soluble vitamin, so people following "low fat" diets may not have the right kind or sufficient fat to absorb and assimilate the vitamin.

The best way to check Vitamin D levels is the 25-hydroxyvitamin D test. The best sources of Vitamin D are cod liver oil, eggs, butter, and oily fish (mackerel, salmon, sardines, and herring).

Magnesium is needed for over 300 different bodily processes.

Magnesium helps prevent heart attacks by regulating the neuromuscular activity of the heart and maintaining normal heart rhythm. It helps prevent calcium deposits, kidney stones, and gallstones. Magnesium is needed for proper Calcium and Vitamin C metabolism. It converts blood sugar into energy. And, has been found to aid in bowel regularity.

A shortage of magnesium can show up in a variety of emotional symptoms such as nervousness, tension, and confusion. On a physical level it can result in tremors, muscular excitability, gallstones, kidney stones, or constipation. It has also been linked to blood clots in the heart and brain, along with brittle bones.

If you drink alcohol or eat a lot of sweets, it may be a good idea to supplement with magnesium. Alcohol and sugar deplete magnesium in the body. Your best sources of magnesium are dark green vegetables, most nuts, seeds, and legumes, whole grains, and avocado.

Vitamin B12 regulates the nervous system, increases energy and agility, and is required for the formation and regeneration of red blood cells. It is necessary for carbohydrate, fat, and protein metabolism, as well as calcium and iron absorption. It helps improves mental condition and attitude.

Lack of Vitamin B12 is related to fatigue, dizziness, poor appetite, itching, stinging or burning sensation of the skin. Severe deficiency will cause pernicious or iron deficiency anemia. Vitamin B12 is important for nervous system, so deficiencies will cause nervousness, neuritis, neuropathy, degeneration of the spinal cord, depression, lack of balance, or loss of motor control.

An important aspect to B12 from my research indicates it needs to come from animal sources to be properly utilized and absorbed by the human body. Tests on "vegetarian" B12 supplements indicate the body is not getting the B12. The best food sources of B12 are meat, most fish (especially the oily ones), crabs, oysters, eggs, and yogurt. Organ meats such as liver, heart and kidney are also high in B12.

Potassium is effective in reducing and preventing high blood pressure. Very important - it works with sodium to regulate the body's waste balance and normalize heart rhythms. It will help to increase energy and support clear thinking by sending oxygen to the brain. It preserves proper alkalinity of body fluids, stimulates the kidneys to eliminate poisonous body wastes, and promotes healthy skin.

Lack of potassium can lead to high blood pressure, poor reflexes, nervous disorders, respiratory failure, cardiac arrest, or muscle damage.

The balance of sodium and potassium is very important in the body. So, loading up on high sodium foods can further get the body out of balance. The best sources of potassium are leafy green vegetables, broccoli, peas, lima beans, tomatoes, potatoes (skins), citrus fruits, bananas, apples, avocados, raisins, whole grains, fish, and meat.

Iodine is required by the thyroid gland to produce its hormones which ultimately control the body's metabolism - or how efficiently you burn calories. It is important for mental agility and promotes healthy hair, nails, skin, and teeth. Iodine is also helpful for breast health, particularly in women.

Lack of iodine can cause serious problems for the body due to the lack of thyroid hormone production. It can lead to weight gain, fatigue, cold hands and feet, dry skin and hair, impaired reflexes, slow speech and mental reaction, loss of physical and mental vigor, and skin sores.

I've been doing a lot of research into iodine recently and have concluded that most of us are lacking. A great source of information on iodine is www.optimox.com.

The best sources of iodine are from the sea - fish, shellfish, and sea vegetables (particularly kelp). Bromine, which is added to many baked goods and breads, is an iodine depletor.

(Part of this article was extracted from the April 2009 Issue of Men’s Health.)