Tuesday, August 04, 2009

Nutritious Couples - Better Together

Vitamin D and calcium: Like most nutrients, calcium is absorbed primarily in the small intestine. If large quantities are present, the body can easily absorb it. But in smaller amounts, the mineral gets absorbed with active assistance from vitamin D. Right now, official nutrition guidelines recommend that adults get 1,000 milligrams (mg) of calcium and 400 international units (IU) of vitamin D daily. For older adults, it’s a bit more. To give you an idea of how much that is, an 8-ounce glass of milk contains 300 mg of calcium and, because of fortification, 100 IU of vitamin D.

There’s debate these days about whether to revise the recommendations to reduce the goal for calcium intake (or at least de-emphasize it) and raise the goal for vitamin D by recommending a daily 1,000 IU vitamin D supplement.

Sodium and potassium: About 90% of the sodium we ingest comes in the form of sodium chloride — salt, in common parlance. Although sodium is an essential nutrient that helps maintain fluid levels in the body, the average American consumes far more of it each day than he or she needs.

Too much sodium can boost blood pressure, and with it, the chances of having a stroke or heart attack. Potassium counters the harmful cardiovascular effects of a surplus of sodium by encouraging the kidneys to excrete sodium. Many studies have shown a connection between high potassium intake and lower blood pressure. In fact, the potassium-to-sodium ratio may be more important than potassium—or sodium—alone.

Almost all of us need to have more potassium in our diets and a whole lot less sodium. And the best way to do that is to load up on fruits and vegetables (prime sources of potassium) and cut back on cookies, salty snacks, fast foods, and ready-made lunches and dinners (prime sources of sodium).

Vitamin B12 and folate: Vitamin B12 and folate work together to support some of the most fundamental processes of cell division and replication. They also metabolize homocysteine in tandem. Folate, which is itself one of the B vitamins, depends on vitamin B12 to be absorbed, stored, and metabolized. Breakfast cereals with added vitamins and minerals typically contain vitamin B12, and in the United States, cereal grains are fortified with folate.

Zinc and copper: Copper and zinc, both essential nutrients, compete for absorption sites in the small intestine. If there’s a lot of zinc around, copper tends to lose out and a copper deficiency may develop. Adults are supposed to get 900 micrograms of copper daily. The daily zinc goals are 11 mg for men and 8 mg for women. Getting enough zinc can lead to a copper deficiency, so it’s important to get enough of both to keep the nutrients in balance.

Neither mineral is rare in the American food supply, so copper and zinc deficiencies aren’t something most people need to worry about. One possible source of zinc overload is, of all things, denture cream.

Niacin and tryptophan: Niacin is probably best known for its cholesterol effects. Taken under medical supervision, large doses (500 mg to 1,500 mg per day) lower “bad” LDL cholesterol and increase “good” HDL cholesterol. But the daily niacin requirement is just 16 mg for men and 14 mg for women.

Amino acids are the building blocks of protein, and tryptophan is one of nine that we need to ingest because the body doesn’t synthesize them on its own. Tryptophan is a supplier of niacin, courtesy of some rather complicated metabolism. So one way to avoid niacin shortfalls is to eat foods that contain a lot of tryptophan. Chicken and turkey are high on that list.

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