DEAR DR. BLONZ: How long can a body go without food? A friend who just suffered a devastating loss has been unable to eat anything. She says she has no appetite, and when she tries to eat anything, her body rejects the food and she throws up. Of course she is losing weight, and has this pale, unhealthy complexion. -- S.F., Santa Clara, California

DEAR S.F.: Deprived of nourishment, the body undergoes a series of adaptations designed to extend life and scale back unnecessary usages of energy. Normally there is constant action in our digestive system: enzymes to be made, cells maturing or being replaced, digestive muscles primed to go. But with no food coming in, the digestive system goes "lights out." When foods are then reintroduced, it can bring about queasiness or nausea until the system is again firing with all cylinders.

Without incoming calories, the body slows down its metabolic rate and lowers its temperature. This means that there will be less circulation near the skin surface, which is one of the reasons why people who go without food feel chilled and tend to have a sallow look about them.

As a friend, you represent an essential source of support. The fact that she is not able to eat indicates that professional assistance may be needed to help her through this rough time. Don't wait.

In the meantime, the body requires more water than any other thing we ingest, so encourage your friend to consume water -- perhaps even sport drinks, as they provide some electrolytes and calories.

If pressed, the human body can survive for many weeks without food, but we would last only a few days without water. The outcome depends on one's state of health, the amount of excess energy (translation: body fat) present at the start of the fast, and whether the body received essential hydration and electrolyte support during the deprivation. I would hope that your friend finds the solace she seeks before testing the limits of her endurance.

DEAR DR. BLONZ: I have read that chromium can alter DNA. I have been taking 200 micrograms a day of chromium picolinate for approximately eight years. Should I be concerned? -- R.S., Glendale, Arizona

DEAR R.S.: Many individuals take supplements that contain chromium. There was some preliminary research reporting that chromium picolinate might have an ability to damage DNA. The research did not really apply to chromium naturally present in foods, or to chromium picolinate taken as a supplement.

At present, dietary chromium has a relatively good safety record, but I will keep you informed if that changes due to more recent studies. The level you are taking is in the National Academy of Science's safe and adequate range, which is set at 50-200 micrograms per day. The "No Observed Adverse Effect Level" (the level at which there are no credibly substantiated adverse reactions) for chromium is 1,000 micrograms per day. Read more on chromium at tinyurl.com/jf8mjgx.

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 that I was six weeks pregnant with my first child. I had no idea that I was pregnant, as I typically have irregular periods. I have a good overall diet, but at the time I found out, I had been drinking a glass or two of wine about every other night with dinner. I am very concerned with whether or not this will affect my unborn child.

Several people have told me that they had a glass of wine every day during their pregnancy, and that nothing happened to their babies. And a friend of mine told me that her doctor said a glass of wine once in a while during pregnancy wouldn't do any harm. How would someone know if that were safe, considering "once in a while" could differ from person to person? -- D.T., Chicago

DEAR D.T.: First, let me offer my congratulations on your pregnancy. Unfortunately, the question of whether your wine consumption might have an effect on your child is impossible to answer with any degree of certainty. We simply don't know, and nobody is ever going to do a study in which they give pregnant women increasing levels of alcohol under controlled conditions to get a more definitive answer. What we do have is research data and statistical tables from which we can discern associations between the level of alcohol consumption and subsequent occurrence of problems with the developing children.

Please understand that you are not the first woman to find out that she was pregnant while engaging in a healthful lifestyle that includes a moderate consumption of wine. It's not an uncommon circumstance, so don't let it wrack you with guilt. A moderate alcohol intake (an average of about one drink per day, with a meal) does not appear to be associated with any harm to the health of the unborn child or the mother. Having the alcohol with food is important.

However, we need to acknowledge that an excess of alcohol is never good -- and, of course, alcohol is not essential for your health, nor the health of your child. Of all the times in life, pregnancy is not the time to take risks, even if they are small.

I recommend that you talk about these issues with your OB-GYN. Your question described your wine consumption as happening "at the time," so I am assuming that you have stopped for now. It is always best to err on the side of safety. I look forward to hearing from you once you have joined that wonderful world of motherhood.

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: A juice bar near me is selling "hydrogen-rich" water with a long list of health claims, including an ability to lubricate joints, detoxify the body and increase brain function. It all seems quite loopy, but the stuff sells. Is there anything to support these claims? -- W.N., Berkeley, California

DEAR W.N.: I compliment your instincts to question these "rich" claims. There is absolutely no basis to assume that the limited amount of hydrogen that will dissolve in a commercial water product will do anything significant for its consumer -- with the exception of costing him or her more money. There are way too many questionable claims out there these days: more than those charged with consumer protection can keep tabs on.

DEAR DR. BLONZ: I recently heard about a new type of water-soluble mineral. The company claims that the minerals are "angstrom sized" and have a 99 percent absorption rate. If this is true, wouldn't this be a far better way for us to get our minerals? -- T.W., Portland, Oregon

DEAR T.W.: The product you mention is being promoted as a new and better way to take dietary minerals, but it smacks of sales talk seasoned with out-of-context science-sounding babble. I predict that aside from dubious testimonials, there is little offered in the way of actual evidence to back up the claims.

Our bodies do a reasonably good job of absorbing minerals from foods; we've been doing it that way for centuries. Food must always be your first choice for obtaining minerals, which means a healthful diet will always be the ticket. But there are a wide variety of mineral supplements that can help you fill in the gaps. You can read more about minerals at tinyurl.com/no5dzly.

DEAR DR. BLONZ: Can I be allergic to niacin (vitamin B-3) to the point where it is harmful to my health? I stopped taking niacin because I get some pretty bad rashes, like an allergic reaction, when I take it. What do you say? Is this normal? -- S.T., Peoria, Illinois

DEAR S.T.: It is doubtful that it's niacin, an essential nutrient, that you are allergic to. Niacin is involved in the health of the skin, nervous system and digestive system, and it also plays a key role in the body's energy producing reactions.

What you are probably experiencing is a "niacin flush," which occurs when large doses of niacin (about 10 times the RDA) dilate the capillaries, the small blood vessels near the skin. There is a release of histamine involved with this reaction, so it is possible that niacin might aggravate other existing allergies you have.

I have no idea why you are taking niacin, so if it was medically directed, be sure to speak with your physician about these side effects. It may be possible to lower your intake of niacin, take it in divided doses or shift to nicotinamide, which is a form of niacin that doesn't induce the flushing effect.

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.