Ask the Nutritionist: Look to dark greens, orange veggies for vitamin A

Updated 2/27/2013 12:13 PM

Q. Can a person get enough vitamin A from milk, fortified cereal and other sources without eating dark green and orange vegetables?

A. You could get all the vitamin A you need without vegetables at all. But carotenoid compounds -- beta-carotene, alpha-carotene and beta-cryptoxanthin -- found in dark green and orange vegetables are important for more than making vitamin A in the body. These vegetables have antioxidant compounds that can protect our cells from highly reactive "free radicals" that could damage cells and lead to cancer, heart disease and other health problems.

In addition, dark green vegetables are a major source of folate, a B vitamin with many health-protective functions.

Dark green and orange vegetables are one part of what you need for good health: these and other vegetables and fruits provide nutrients Americans need more of like potassium, a mineral that can help control blood pressure. They also supply a host of phytochemicals. Phytochemicals are natural compounds found in plant foods that seem to block several steps in cancer development.

Regardless of where else you get vitamin A, aim for at least five servings every day of a variety of vegetables and fruits, and then add more for additional health and weight control benefits.

Q. I've heard that fruit should be eaten alone rather than with other foods. Is that true?

A. No. You may see articles suggesting a number of problems that stem from eating fruit along with other foods, but none are based on science.

One thing you may read is that you cannot digest fruit if other foods are present in your stomach at the same time, so the fruit ferments causing indigestion or heartburn after a meal. This is absolutely untrue: carbohydrate digestion begins with enzymes in the saliva and continues as food passes through the stomach and then the intestine. Enzymes that break down carbohydrate in fruit are separate from those that break down protein and fat.

Eating different types of food together does not inhibit digestion. The stomach puts out large amounts of acid; food does not sit there rotting or fermenting.

You may also hear claims that fruit combined with other foods leads to being overweight because the body cannot digest them. But this, too, is untrue. Mixing foods at a meal does not leave the body unable to digest them. And even if it did, undigested food passes out as waste material; it cannot possibly turn into body fat.

Excess body fat comes from just the opposite: more calories consumed, digested and absorbed than our bodies burn.

If anything, combining fruits with other plant foods like vegetables and whole grains could be beneficial. Fruit can be a filling appetizer to help limit calories at a meal, a delicious addition to salads, and a satisfying way to end a meal on a sweet note. Don't be afraid to combine fruit with whatever foods you want.

• Provided by the American Institute for Cancer Research.

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