DEAR DR. BLONZ: I read your column about statins and cholesterol, and have a related question. I was recently advised (again) to avoid foods with cholesterol because I have too much in my blood, but many of the foods I love to eat contain cholesterol. Exactly how bad is cholesterol? What is the connection between the amount of it you eat and the amount in your blood? I have had discussions about this with my physician, but would like your advice. -- S.T., Greenville, South Carolina

DEAR S.T.: There are many factors in the connection between dietary cholesterol and that found in a blood test.

Cholesterol is a lipid substance, part of a large group that includes fats and oils. These have a unique ability to oxidize into troublesome compounds that increase disease risk, most notably cardiovascular disease. Some lipids are worse than others, but all seem to have this potential. Because our blood is a water-based medium, lipids must be transported around attached to proteins appropriately named “lipo proteins.”

A member of the sterol family of lipids, cholesterol is a large, complex compound with a build that looks like a piece of chicken wire. It was found initially in gallstones, the painful masses that sometimes form from bile inside the gall bladder. Accordingly, the name “cholesterol” is Greek for “the sterol found in hardened bile.” Cholesterol serves many functions in the body: It is needed to help the brain work properly, it keeps our skin watertight and it provides the basic building block for sex hormones and other essential substances.

The negative image of cholesterol comes from studies where elevated blood levels were found to be a predictor of disease. Examination of damaged arteries in those with cardiovascular disease tended to show a cholesterol-laden buildup. It was unclear whether cholesterol was directly responsible, but the weight of circumstantial evidence remains significant.

There is an important distinction between the cholesterol in our diet and the level in our blood. In the average individual consuming a balanced diet, the effect of dietary cholesterol on the blood level appears to be of secondary importance. Only about half the amount of cholesterol we eat gets absorbed. And if there were absolutely no cholesterol in our diet, the body would make all it needed on its own.

A healthful diet and lifestyle have always been key, but some of us must take special care due to a genetic predisposition to produce excessive amounts of cholesterol.

Greens, grains, fresh fruits and vegetables, nuts and seeds have the right stuff to help the body process dietary fats and cholesterol. You didn’t mention your exercise habits, but keep in mind that an active lifestyle keeps your muscles and systems demanding fats for energy, rather than having the bulk of dietary calories routinely headed for storage. It is also critical to avoid an excessive intake of sugars.

When we eat and live well, the importance of dietary cholesterol shrinks dramatically. You state that many of the foods you love to eat contain cholesterol. You also indicate that this is not the first time you have been counseled. If you want to keep your cherished foods on the plate, make that shift in your lifestyle and diet to include more foods and activities to keep your healthful rhythms intact.

Send questions to: “On Nutrition,” Ed Blonz, c/o Andrews McMeel Syndication, 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 enjoy fresh grapefruit juice in the morning with breakfast. Friends have told me that grapefruit juice interferes with the absorption of vitamins, pointing to its interference with prescription drugs as proof. I searched the web for info and found that grapefruit juice interferes with some prescription drugs, but found nothing about it interfering with vitamin absorption. I would appreciate it if you could shed some light on this issue, including whether other citrus juices act in a similar way. -- S.M., Tulsa, Oklahoma

DEAR S.M.: There is no evidence that vitamin or mineral supplements are affected by grapefruit juice in the same way it affects certain medications. However, since I have received several questions on the exact nature of the “grapefruit effect,” I want to clear up some of these issues.

The effect has to do with compounds known as furanocoumarins (fur-RAN-oh-koo-mir-inz) and their ability to inhibit the activity of certain enzymes in the body. High levels of these compounds are found in grapefruits and pomelos (genetic ancestors to grapefruit), and lesser amounts in the Seville (bitter) orange, which is often used in flavorings and orange marmalades. Relatively small amounts have been reported in limes and lemons; sweet citrus, such as oranges and tangerines, contain little, if any. In varieties that contain furanocoumarins, they will be found in both the fruit and the juice.

As you know, our bodies have systems that break down foreign substances before they can be absorbed. Consider that while medications are given for a reason, from the body’s perspective, they are foreign substances that need to be eliminated. One of the stars of the “disposal” system is the enzyme system known as cytochrome P-450 (CYP3A4), which is present in the liver -- the organ that does the majority of the breakdown. It is also found in the walls of our digestive tract, serving as a gatekeeper to limit absorption.

The bottom line is that only a portion of any medication taken orally ends up in our general circulation; this is factored into the determination of therapeutic doses. (Meds that tend to be completely destroyed must be given via other means, such as an injection, which avoids what’s referred to as “first pass metabolism.”)

The connection with grapefruit is that the furanocoumarins prevent CYP3A4 from doing its job. This can result in higher-than-desired levels of medications in the body. The levels are not only elevated, but they remain so for extended periods.

The effect was discovered by accident when grapefruit juice was used to disguise the taste of treatments used in a research study. The results did not match expectations, and it was found that the juice itself affected how the treatments were absorbed and broken down. More studies followed, leading to an understanding of how the processing of medications “handled” by CYP3A4 was changed when furanocoumarins were around. In one study, the effect was still noted 24 hours after grapefruit juice was consumed.

I encourage you to check with your pharmacist or physician to see whether any medications you are taking might be affected. But as mentioned above, there is currently no evidence that vitamins are subject to this effect.

Send questions to: “On Nutrition,” Ed Blonz, c/o Andrews McMeel Syndication, 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: There is a constant argument at our house about the role of statins in helping determine what you should eat. If a person who formerly had elevated cholesterol takes a statin drug and it succeeds in bringing their level into the normal range, is there any reason, aside from weight gain, why they should not eat high-fat, high-cholesterol foods? I am frustrated by this person bragging that they are now insulated from the dangers of their diet. -- M.T., Broken Arrow, Oklahoma

DEAR M.T.: Medications to control an elevated blood cholesterol level should not be thought of as a license to eat and live in an unhealthful manner. Taking a statin, or any cholesterol-lowering drug, provides an artificial means to correct a symptom of imbalance in the body. Whether due to a genetic predisposition, poor diet or lifestyle factors, the cholesterol becomes elevated for a reason. It makes little sense to then dismiss the problem with thoughts that a pharmaceutically lowered cholesterol level fixes everything. It may provide a means to correct the symptom, but it does not relieve us of the responsibility to treat our bodies with care.

If you need the medication, by all means use it. Wouldn’t it also be a worthy goal to make the appropriate dietary and lifestyle adjustments so that the need for the drug was reduced or eliminated? Evidence shows that such changes go well beyond better numbers on a lab test; that would indeed be something to brag about.

DEAR DR. BLONZ: I buy raw almonds and bake them in a toaster oven at 250 degrees for about half an hour. Does roasting the almonds cause the oil in the nuts to undergo a change that turns it into saturated fat? I have also heard that heating almonds diminishes their nutritional value, specifically vitamin B. Is this the case? Are raw almonds preferable if nutrition and health value are the only considerations? -- M.C., San Diego

DEAR M.C.: The roasting of nuts does not affect the minerals they contain, and it does not make their oils more saturated. Roasting is associated with decreases in -- but not the elimination of -- a few vitamins, but this should not be considered a significant impact on their considerable value as a healthful food.

The choice between raw and roasted almonds, or other nuts and seeds, should be based on your personal preference. I tend to have almonds and peanuts available nearby and consider them to be excellent food.

Send questions to: “On Nutrition,” Ed Blonz, c/o Andrews McMeel Syndication, 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.