DEAR DR. BLONZ: What controls the body's ability to make cholesterol, and how much is made? Can we manufacture much more cholesterol than we take in with our food? -- E.D., Palo Alto, Calif.

DEAR E.D.: Even in people without a dietary source, such as strict vegetarians or vegans, the body makes all the cholesterol it needs. This is because cholesterol is an essential structural element in every cell of the body. In addition, cholesterol is a raw material for a number of hormones, including estrogen and testosterone. Many cells in the body can make cholesterol, but much of it gets made in the liver.

There are feedback mechanisms to stop cholesterol production when there is enough; ideally, when cholesterol is absorbed from the foods we eat, the liver and the body's cells will make less. There are a number of genetic conditions in which the body is misprogrammed to make more than it needs. They are referred to as familial hypercholesterolemias, and there is an informative page explaining these rare conditions at the National Institutes of Health (tinyurl.com/ld48). However, a more common condition is an unbalanced diet: too much fat and sugar and not enough grains, fiber, fresh fruits and vegetables. This can contribute to elevated blood cholesterol levels with especially high levels of the LDL (low-density lipoprotein) cholesterol associated with chronic disease. When there is stress, smoking, excess alcohol and lack of physical activity, things can get even worse.

DEAR DR. BLONZ: I filled out an online health questionnaire, which told me I had a "sluggish liver." Three of the items I had checked were cellulite, a hard time losing weight and frequent pains in the hips. The site recommended a particular dietary supplement that, of course, they were selling, which made me quite suspicious. What is known about sluggish liver? -- B.N., Janesville, Wisc.

DEAR B.N.: I have seen the term "sluggish liver" used to explain everything from hemorrhoids to headaches, but the entire concept of the "sluggish liver" has no real medical meaning. The liver is a very complex organ, perhaps the hardest working and most diverse organ in our body. Its responsibilities include: making blood and various blood proteins; detoxifying chemicals, including alcohol and all matter of drugs and contaminants, whether they are eaten, injected, absorbed through the skin or present in the air we breathe; manufacturing and storing glycogen, a form of stored glucose (blood sugar); manufacturing fats whenever the body has more dietary energy (calories) than needed at the moment; facilitating the burning of fats when there is insufficient energy; producing bile, a substance needed to digest fats; storing iron and other vitamins and minerals; and making many of the factors that help clot the blood.

The implication of such an impressive list is that there are serious consequences if the liver is not functioning up to par. But what does it mean if it is "sluggish"? It is just too vague a term. Using it is like telling a new doctor that you don't feel well and then expecting a complete diagnosis and treatment plan.

There might be nothing wrong with your liver, but if there was, it would not be something you could uncover through an online questionnaire. A health professional can take a careful history, do a physical examination and order any appropriate laboratory tests. For more background, see the NIH page on liver diseases is at: tinyurl.com/4p8kcv.

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: Two weeks ago, I found out I was seven weeks pregnant with my second child. I typically have irregular periods and I had no idea that I was pregnant. I had been drinking wine periodically with dinner, but I am now concerned that this might have affected my unborn child. Aside from this, I have a good diet and take good care of myself. Several women have told me that they had a glass of wine every day or so during their pregnancies, and that nothing happened to their babies. Another friend heard from her doctor that a glass of wine once in a while during her pregnancy wouldn't do any harm. But then I read the horror stories. How could anyone know what is safe or unsafe given this conflicting information? Please do what you can to clarify. -- D.D., Berkeley, Calif.

DEAR D.D.: First, let me offer my congratulations on your pregnancy. The question of whether your wine consumption might have had (or will have) an effect on your developing child is difficult to answer with any degree of certainty. We simply don't know. Research and statistical tables are available that reveal associations between the level of alcohol consumption and subsequent problems for the developing child. In most cases, the connection gets made between risk and the habitual amount of alcohol consumed.

You are not the first woman to find out that she was pregnant while engaging in a healthful lifestyle that might have included a moderate consumption of wine. It is not an uncommon circumstance, so don't let it consume you with guilt. There are many studies with gobs of statistics in the scientific literature. Abusive or binge drinking has been associated with problems, but a low-to-moderate intake (not daily, or less than an average of one drink per day with a meal) does not appear to be associated with any harm to the health of the child or mother. Having the alcohol with food is important.

Indeed, in a systemic review of available evidence in the January 2007 issue of BJOG, the International Journal of Obstetrics and Gynaecology, it was reported that there was no convincing evidence of adverse effects from low-to-moderate levels of alcohol intake. This being said, however, it must be emphasized that any excess of alcohol is definitely dangerous, and that alcohol is not essential for the health of your child. Of all the times in life, pregnancy is not one to take risks, however small. I recommend that you talk about these issues with your OB/GYN, and until you have had that conversation, consider tapering off your consumption of wine, if you haven't stopped already. It is always best to err on the side of safety.

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: In California there is a ballot issue (Proposition 37) about requiring labels on genetically modified foods. I am interested in your take on this. -- M.Q., San Jose, Calif.

DEAR M.Q.: In the past, improving a food crop via plant breeding was a hit-or-miss proposition that took years to achieve any measurable success. Genetic modification, a type of biotechnology, removes much of the guesswork by identifying the specific genetic code associated with a desired trait. This code can then be removed and made a part of the genetic instructions of a target plant. For example, you could take genes that contribute to great taste in one variety and transfer them to another variety that has poor taste but a longer shelf life. If it works, you could end up with a variety that has both qualities.

Plants might also be modified to grow in soil and water conditions where they previously could not survive. Genetic modification also has to the potential to create crops that remain fresher longer, are less dependent on chemical fertilizers and pesticides, and are more nutritious. For example, grains tend to lack certain amino acids so they cannot serve as good sources of protein. Genetic modifications can be engineered to provide the missing amino acids, turning easy-to-grow foods such as grains into inexpensive sources of complete proteins. Such developments would have little impact in the U.S., where we already eat too much protein, but they could represent a life-saving advancement in developing countries where single grains are often the main food eaten.

However, with such power and potential, there are questions of safety. When reprograming the way things grow, is it just a matter of time before a mistake opens a Pandora's box of new diseases, bugs, or even super weeds? It's a fair question.

There is government supervision through the FDA, EPA and USDA, but there is little practical control over experiments conducted in individual laboratories. Questions need to be constantly asked: Is this research necessary? Will this development feed more people, help save lives or provide a higher quality of life for a greater number of people?

We don't always know who is going to ask these questions, if anyone, and who will determine the answers. It is because of these unknowns that, at this point, biotechnology must be regarded with cautious optimism. As great as its potential is, the forces likely to decide its future are those who control the purse strings. Government coffers are running dry and those of private companies are usually salted with economic self-interest, a fact that may not coincide with the good of humanity.

As an example, genetic modification can create crops that are resistant to a particular pesticide or herbicide. By growing these varieties, more of a company's chemicals could be applied to kill pests without killing the crop. There is also the option of genetically engineering plants to produce their own pesticides. Rather than a step toward less dependence on synthetic chemicals, such "advances" would provide further rationale for their use. There is also the advent of patenting genetically modified seeds, creating corporate ownership of certain crops.

Few could argue with the use of science to create varieties of plants with higher nutritional quality, a higher resistance to disease or greater tolerance to variations in soil and temperature conditions. Such developments could change unfertile regions into productive farmland. This would be invaluable for those parts of the world constantly besieged by drought and famine. But if genetic modification is used only for profit, the development of crops to feed the hungry -- and the long-term health of the land and those who work it -- may shift to secondary importance.

It's in your best interest to follow this issue and make your opinions known with your voice, your vote and your wallet. It is essential to understand that genetic modification of foods represents the employment of a scientific method that has multiple personalities. Knowledge is power, and it is to our benefit to know where and how genetic modification is being used. As such, I favor California's Proposition 37. While not a perfect solution, it is definitely a step forward.

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.