DEAR DR. BLONZ: My boyfriend takes a dietary supplement that contains bovine colostrum to increase his lean muscle mass. Coincidently (or maybe not), he is noticing that his heart has been racing a lot. Do you think there is a connection? -- S.S., Oakland, California

DEAR S.S.: Colostrum is the first fluid from a mother's breast following the birth of her young. It is a liquid that is rich in "immune proteins," tailored to give the newborn's immune system a boost until it can begin manufacturing disease-fighting antibodies on its own. This type of protection, referred to as "passive immunity," is considered to be one of the great health advantages to breast-feeding.

What, then, does a colostrum supplement -- and one that comes from a cow -- have to do with an increase in muscle mass in humans? Little, I am afraid. As harsh as it sounds, this type of colostrum only makes sense if you are less than 6 months old and bovine in origin. If you know of any solid scientific evidence to the contrary, I would enjoy seeing it. There are certainly more traditional and reliable methods to build muscles.

As for the racing heart, it is certainly possible that something in the supplement is causing that symptom. It could be allergenic in nature, or it could be due to a stimulant in the product. Check the ingredient label to make sure there are no surprise ingredients. It would be prudent for him to stop taking the product and see if things settle down.

DEAR DR. BLONZ: I recently had cardiac bypass surgery. I'm now in search of a healthy lifestyle and am naturally concerned about my diet. I have read that the oils in certain cold-water fish are beneficial, so I've been eating sardines because they are easily available. I recently looked at the label of the brand I buy and saw that I have been consuming 24 grams of total fat, 6 grams of saturated fat and 140 mg of cholesterol. These figures seem excessive. My question is, should I discontinue eating sardines? Or are some of these fats the so-called "good" fats? -- F.M. San Diego

DEAR F.M.: There is no need to stop eating sardines, especially if you enjoy them. You might, however, consider cutting back. The totals you cite are for an entire tin, which is the equivalent of about one cup of fish. According to my nutrient database, aside from its 24 grams of fat, one cup of sardines also contains over 50 grams of protein, and about 800 milligrams of calcium. These numbers approach the amounts needed for the entire day!

Sardines have a moderate fat content, and they do contain the heart-healthy omega-3 fats. The key to a healthful diet, however, is variety and moderation. You should be eating a variety of fish, not only sardines, and making sure that every meal includes whole foods, such as fruits, vegetables and whole grains. Blend these all together with a daily serving of physical activity, and you'll be on your way to that healthful lifestyle you seek.

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 was diagnosed with chronic idiopathic urticaria, and it is important that I go on a low histamine diet -- at least, that is what I have read. Is there any guidance that you might provide? There is little information available about histamine in foods. -- S.I., San Jose, California

DEAR S.I.: First, to break down the diagnosis for your fellow readers: Urticaria is a condition that can involve hives and itchy rashes. The "chronic" descriptive means that it is an ongoing condition, as opposed to an itch from an insect bite that annoys and then is history. "Idiopathic" means it's something you have developed and it is unclear why.

The idea of a low-histamine diet is somewhat misleading, because preformed histamine is not found in foods to any appreciable degree. You may not be seeking a diet that is "low in histamine" so much as one that limits foods that tend to trigger a histamine release within body.

Histamine is involved with inflammation, and while we tend to think of inflammation as a bad thing, it is an important element in systems designed to increase blood flow to specific regions. It can also facilitate tissue repairs, the elimination of unwanted substances, and immunological responses to microbiological invaders. The body makes its own histamine from histidine, an essential amino acid; histamine is then stored in "mast cell" reservoirs that are distributed throughout the body.

As can be discerned by the existence of "anti-histamine" products, histamine also has a dark side. It is responsible for the cold- or allergy-like symptoms of sneezing, itchy eyes, runny nose and, in your case, urticaria. Because of these effects, we often turn to antihistamines to provide a measure of symptomatic relief.

A low histamine-producing diet is a quest to identify offending foods. Because histamine is often involved in allergic-type reactions, the first type of food to avoid are those most likely to promote allergies or hypersensitivity reactions, including: shellfish, eggs, cheese, hard sausage, sauerkraut, chocolate, nuts, tomatoes, berries, wine and beer. This would have to be tailored to your situation, and that can mean keeping a log of foods and any untoward experiences related to your condition.

I have also seen lists that say to eliminate food additives such as sulfites, benzoates, nitrites, salicylates, preservatives, artificial colors (especially tartrazines), as well as other foods such as milk, citrus, cola, cinnamon, peas, beans, pork and wheat.

The next foods to consider avoiding are those with unusually high concentrations of "free" histidine. While not an issue with the histidine that is a part of protein, free histidine in foods is a potential problem because there are enzymes that can change this histidine into histamine.

Foods with high levels of free histidine include fish such as tuna, bonito, mackerel, blue marlin, sardines, herring and anchovies. Avoiding these high-histidine foods removes another possible contributor to an increased histamine level in the body.

A study published in the February 2000 issue of the European Journal of Clinical Nutrition found that this strategy has potential: Patients with chronic idiopathic urticaria experienced significant improvement after 21 days on a diet that decreased the types of foods above. Consider consulting with a dietitian to help formulate your strategy.

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 have concerns about contaminants in fish oil supplements. Is an omega-3 supplement sourced from flax a better alternative? -- F.L., Phoenix

DEAR F.L.: I recommend eating fish over taking fish-oil supplements. Population studies have shown that those with a regular consumption of fish have a lower risk of several chronic diseases, including heart disease, hypertension and certain inflammatory conditions, such as arthritis.

Your question, however, relates to supplements, so let's consider the issue.

The key components are specific omega-3 fatty acids. Fish containing high levels of these include salmon, mackerel, tuna, herring, anchovies, sardines and trout. There are also omega-3 fatty acids in flaxseed and, to a lesser extent, canola and walnut oils, but these are not the same as those found in fish.

To be called an omega-3 means that the first unsaturated bond is on the third carbon of the chain. In fish, we have omega-3s often referred to by their initials: EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). They are 20 and 24 carbons long, respectively. The omega-3 in flaxseed and other plant sources is linolenic acid, which is 18 carbons long.

Most people need more omega-3 fats in their diet, whether they come from fish or flax, but there are unique benefits in EPA and DHA.

If you do consume the 18-carbon linolenic acid, your body has the ability to elongate some of it into EPA and DHA, but only a small amount makes it through this process. It is, however, better to have omega-3s from flaxseed than to not have any at all.

Plant sources of omega-3 fats are relied upon by vegans. In addition to fish, EPA and DHA can be found in krill (a crustacean) and in some forms of algae; it is up to the individual to decide the boundaries of their vegan eating plan. I would be remiss if I didn't mention that flaxseed has other health attributes: It is an excellent source of dietary fiber and lignan, a phytochemical that may have anti-cancer effects.

As for pollution, this remains a disturbing topic, and some fish populations have been affected by various contaminants. When eating fish, steer clear of those caught or raised near industrial plants, and stick with those from offshore or deep-sea areas, or from lakes and streams known to be free from harmful chemicals. You might seek guidance from a reputable fish market.

Where supplements are concerned, it is best to check individual products to find one that is free of contaminants. There are processes that allow manufacturers to filter out environmental toxins without affecting the level of the omega-3 fatty acids. Look for an appropriate description on the label stating that the product is contaminant-free. If in doubt, give the manufacturer a call.

One final note: Fish oil supplements should be avoided by those with bleeding disorders and those on anticoagulant medications. Caution is also dictated for those with high blood pressure. Always consult your physician if you have any questions.

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.