DEAR DR. BLONZ: Is there a best food for fiber? I want to increase my intake and want something convenient that does not taste like cardboard. -- S.S., Concord, California

DEAR S.S.: We should aim for about 14 grams of dietary fiber for every 1,000 calories consumed, but Americans tend to eat rather low on the fiber scale. Population studies continually find that an increased consumption of dietary fiber is associated with a lower risk of diabetes, coronary artery disease and obesity. The best foods in terms of convenience and fiber content would have to be breakfast cereals: Cereal fibers are associated with the most overall importance to our health. There's no better way to start the day than with a bowl of fiber-rich cereal topped by fresh fruit. That is what I do. I also consider making time for breakfast to be a valuable adjunct to health.

If fresh fruit is unavailable for your morning bowl of cereal, consider dried fruits. They are an often-overlooked fiber resource with a great variety of rich fruit flavors, and the fact that they are dried gives them an extended shelf life. Their concentrated sugars also allow you to reduce or eliminate other sweeteners on your cereal. Dried fruits also work in your child's lunch box, or as a quick office treat, making a between-meal power snack when combined with nuts.

Next we have nuts, seeds, vegetables and grains, with legumes (beans) and whole grains being particularly low in fat and high in fiber. What about fiber supplements? There are plenty out there, and they may be appropriate when certain health issues are involved. But why even think of a supplement when you have all the fiber you need in whole grains and fresh, whole foods, which are the precise types of foods you should be eating? For more on fiber, consult the National Institutes of Health collection at tinyurl.com/2qp9l2.

DEAR DR. BLONZ: Does sunscreen prevent the absorption of vitamin D? I walk daily for about 30 minutes, but depending on the weather, I am covered with a light sweater or sunscreen. I am over 60 and take a calcium supplement with 1,000 IU of vitamin D. Am I getting any vitamin D from my daily exposure, or should I be taking additional amounts in a supplement? -- P.F., Oakland, California

DEAR P.F.: Sunscreens come in various strengths, but in general they are specifically designed to prevent ultraviolet rays from penetrating your skin. It is these rays that are necessary for the body to make its own vitamin D. You do, however, seem to have your D covered. Is there a particular reason you are considering taking more? You can discuss this with your physician. There are blood tests to determine the level of vitamin D in your body. Read more on sunscreens at tinyurl.com/kp895ep. The National Institutes of Health has a list of articles on vitamin D at tinyurl.com/mmtlu68.

Send questions to: "On Nutrition," Ed Blonz, c/o Universal Uclick, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to questions@blonz.com. Due to the volume of mail, personal replies cannot be provided.

DEAR DR. BLONZ: My husband and I eat a good diet, doing our best to eat many different foods and lots of fruits and vegetables. We recently began taking a multivitamin packet of pills, along with a separate calcium, magnesium and zinc supplement, every morning with our breakfast. Soon after starting this practice, my husband started experiencing nausea an hour or two after taking the pills. I have not experienced this problem. He discontinued taking them, then tried them again a month later and experienced the same discomfort.

Is there a particular vitamin or mineral that you know of that could be doing this? His diet is not as healthful as mine, so I believe he should continue to take some sort of supplement. -- P.J., San Diego

DEAR P.J.: First, my compliments on your attempts to eat a healthful diet. While uncommon, some individuals do experience mild nausea or some other untoward gastrointestinal reaction after taking a multivitamin supplement, particularly if there are many pills involved. There may not be a particular nutrient responsible here; rather, it could be the fact that you are taking a number of pills and capsules all at the same time. When they dissolve together, they can irritate the stomach.

Check the potency to make sure that you are not getting well over the Daily Value for the nutrients. If some of the nutrients are exponentially high, your husband might try a product that provides no more than 100 percent to see if that tones down the reaction.

If one is taking a supplement, it makes sense to take it with, or after, a meal -- and the more complete the meal, the better. If breakfast in your house is typically small, you might consider taking your supplements with a meal that has a better showing of the food groups, or splitting the pills between two meals.

Whatever you decide, always remember that vitamin and mineral pills are meant to supplement a healthful diet, not replace it. This is only affecting your husband, so here are some other questions to consider: How well does he eat during the rest of the day? Does he experience indigestion at other times? Could there be a predisposing stress element involved here? How about his exercise/activity habits? All these factors can contribute to a vulnerability to digestive issues. The National Institutes of Health has a good discussion of indigestion at tinyurl.com/3do3ld. And here is a link to a page offering tips for buying multivitamins: tinyurl.com/pwngld8.

DEAR DR. BLONZ: Thank you so much for your clear, scientifically based, helpful comments about smoking cessation. These days, there is so often a promulgation of nonsense "tips" like colon cleansing. -- R. Oehm, cardiologist

DEAR DR. OEHM: Thanks for your note. As a physician, you understand that the cells that make up the lining of our intestines are constantly being replaced. As reported in the March 2009 Annual Review of Physiology, there is a change in this layer of cells every four to five days! The idea that toxins are caked onto these cells, and that they hang around for months or years to wreak havoc with our health, is baseless. There remains, however, that subculture that opts for the archaic flushing procedure with the promise that it can provide just about any beneficial health effects that one might seek.

The whole foods and fiber we eat determine how well our digestive and elimination systems work, and they should be viewed as an essential part of our daily diet. The message here is that it is our diet and lifestyle, not colon cleanses, that contribute to our overall state of health.

Send questions to: "On Nutrition," Ed Blonz, c/o Universal Uclick, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to questions@blonz.com. Due to the volume of mail, personal replies cannot be provided.

DEAR DR. BLONZ: I am concerned about lead poisoning. What is the best way to check for lead in paint? Our vacation rental is in a dated cottage and there is a powdery deposit on the walls. The rental agency doesn't know the answer. Our dog is with us, and we are also concerned about him. I need to find out more about what goes wrong with lead and how to find out discreetly whether there is a problem. -- S.R., San Diego

DEAR S.R.: The most immediate step is to find out whether there is lead on the walls. There are a number of lead-check products, some of which will probably be available at a local hardware store. I have used LeadCheck swabs (leadcheck.com) by 3M, but there are a number of products that can provide the information you need. They all involve a liquid swab with an indicator substance that turns a certain color when lead ions are present. It is a simple, straightforward test that can be used on any surface, and one that will let you know instantly -- and discreetly -- whether the powdery deposit on the walls in your rental represents a risk. These swabs can also be used to test for lead in any other items, such as chew toys used by the dog.

You are right to be concerned. Lead can enter the body in a number of ways, the most common being the consumption of substances containing lead, or the inhalation of lead in dust. If the walls have leaded paint, powder from the paint can drop to the floor; every time the floor is swept, the lead can become airborne, presenting an increased risk of inhalation. Lead poisoning in children, for example, is often related to the consumption of leaded paint chips that peel off the walls, or by putting hands or toys with lead dust on them in their mouths. In adults, common sources are leaded water pipes, leaded pottery used for cooking or eating, leaded food-storage containers, or working in industries where lead-containing compounds are used.

Aside from testing kits for the suspect items, there is a blood test that can determine if excessive lead has entered the body. A physician can provide a more precise evaluation. The good news is that the body is able to rid itself of lead; the bad news is that it does so slowly. The issue is that if you are in a lead-contaminated environment, the lead comes in faster than the body can eliminate it. That means the essential first step is to stop the exposure.

The symptoms of lead poisoning in adults are varied, including anemia, fatigue, depression, hypertension (high blood pressure), heart failure, abdominal pain, gout, kidney failure, wrist or foot weakness or reproductive problems. In children, lead poisoning symptoms include anemia, fatigue, decreased appetite, digestive problems, sleeplessness, learning problems and lowered I.Q. The Environmental Protection Agency has an excellent "Learn about Lead" page at tinyurl.com/ohsk2z5.

In dogs, the symptoms of lead poisoning include distinct changes in their nervous and digestive systems, including seizures, uneven gait, colic and vomiting. Consult your veterinarian if you have any questions. You can find more about lead poisoning in dogs at tinyurl.com/nl3qed6 and tinyurl.com/32r4uj.

Send questions to: "On Nutrition," Ed Blonz, c/o Universal Uclick, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to questions@blonz.com. Due to the volume of mail, personal replies cannot be provided.