DEAR DR. BLONZ: What are the concerns about the use of soy and flax if you have breast cancer? -- S.B., Chicago

DEAR S.B.: Soy and flaxseed contain substances that are similar in structure to the human hormone estrogen. In soy, these are the isoflavones, while in flax, they are the lignans. These plant versions of estrogens, called phytoestrogens, cannot take the place of our own, but they can play tricks on some of the estrogen receptors in our bodies.

Your question relates to the use of soy and flax with breast cancer patients. It is known that certain types of breast cancer grow faster when estrogen is around. These cancers are referred to as estrogen receptor positive (ER+) cancers. Research has found that phytoestrogens can block estrogen's ability to stimulate the growth of these estrogen-sensitive cancers. The cancer-fighting drug Tamoxifen is designed on this very principle.

When considering the use of soy and flax with a breast cancer patient, it's of primary importance to know if the cancer is ER+. A next consideration is whether Tamoxifen treatment is being used, which is more likely with estrogen-sensitive cancers.

In such instances, it would be unclear whether the presence of additional phytoestrogens from soy and flax would have a chance of making things better, or work at cross-purposes to the Tamoxifen. There are studies underway to determine if fixed intakes of phytoestrogens might be therapeutic, but the particulars have yet to be worked out. That means it would be wise to refrain from high intakes of these phytoestrogen-containing foods until you have discussed it with your oncologist, or a dietitian working with the practice. This is a relatively new area, where the reliable research evidence is somewhat limited.

Nobody wants to make a misstep. But if the breast cancer is not estrogen receptive, and there is no history of these types of cancers in the family, I am not aware of any reason why these whole foods can't be a part of your plant-based diet. Flaxseed contains fiber and omega-3 fats, while soy contains the essential omega-6 fats. A regular intake of soy protein has been shown to help decrease the risk of heart disease.

The American Cancer Society has a discussion of soy and the risk of breast cancer at tinyurl.com/hqgcxt7.

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've always thought that if I have all my fruits, vegetables and grains -- organic, when possible -- along with other foods in the amounts recommended, I should not need any dietary supplements. Recently, I attended an anti-aging conference where I was told that the soil throughout the United States is 85 percent depleted of its vitamins and nutrients. They said eating organic does not mean you are getting your fruits and vegetables from nutrient-dense soil. Is this a fact? I am hoping you can help me identify areas of the country, or the world, where a person can be sure to get produce with the proper nutrients. -- R.V., San Dimas, California

DEAR R.V.: The information from that anti-aging conference was off the mark. While I am definitely pro-organic and support it when possible, it is better to eat conventionally grown produce than to limit your intake of fruits and vegetables.

The often-heard "soil-depletion" argument can be very misleading. In addition to their need for sun, water and proper temperature, fruits, vegetables and grains -- whether grown organically or through conventional methods -- require certain nutrients to develop. If a plant's essential minerals are not in the soil, for example, the plant simply won't grow, or it will fail to develop normally.

Minerals that aren't needed can also be taken up by a plant. Foods grown in selenium-rich soil, for example, often contain more of this mineral than the same plants grown in selenium-poor soil. A plant's mineral content can also vary according to the time of the growing season and the length of time the plant has had to grow.

The idea of "vitamin-depleted" soils makes even less sense. Plants do not get their vitamins from the soil; they, along with other phytochemicals, are synthesized within the plant itself. The amount of a particular vitamin found in a fruit, vegetable or grain is determined by the plant's genes, not by the amount present in the soil. After harvest, vitamin content can decline with time, and some vitamins can be affected by cooking.

It then follows that there really isn't a specific area of the country (or the world) where a person can be sure that the fruits and vegetables have the "proper nutrients and vitamins." If you are concerned about the adequacy of your diet, if you have health issues or are at risk for certain chronic diseases, there are a number of websites where you can enter the foods you eat and get a report of nutrients consumed. As is typical of today's online "diet," some of these sites charge money, while others provide the service for free -- but with a "side dish" of advertisements.

Variety is key wherever you live, and we are blessed with a transportation system that brings us foods from all over. Eating well is the cornerstone of good health, and a good diet places you head and shoulders above the vast majority of your peers.

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 partner had an emergency heart valve replacement and is now on the blood thinner Coumadin, perhaps for the rest of his life. The surgery saved his life, so we are extremely grateful, but he has been told not to eat green vegetables anymore. This is proving very hard, as we love our veggies. Eating just yellow and white ones doesn't allow much variety. Are there any web resources, books, charts or cookbooks that would show us how to insert some green veggies occasionally, while keeping his blood levels correct? -- J.B., Seattle

DEAR J.B.: I can only imagine the difficult times you have gone through, and am pleased to hear about the success of the procedure. There may be other anticoagulant (blood thinner) options to consider; your partner should discuss this with his physician. My answer will address Coumadin, since that is what he's currently taking.

First, some background. Coumadin, the brand name for warfarin, gets its abilities as a blood thinner from its opposition to vitamin K, which plays an integral role in blood clotting. The warning against green, leafy vegetables stems from the fact that vitamin K is present in these foods. By increasing the vitamin K in your diet, you could overwhelm the ability of the Coumadin to do its job.

The appropriate dose of Coumadin is determined through a series of blood-clotting tests. These are done with the patient's blood, so they will reflect his normal eating habits. From that point on, the key is to hold constant any substances that would affect blood clotting. It is not that your partner needs to completely eliminate vitamin K -- rather, once his Coumadin dose is determined, he should keep his level of vitamin K as constant as possible.

Other Coumadin-related advice includes checking with his doctor on other medications he might be taking. Aspirin, for example, affects blood clotting. Certain herbs can also interact with Coumadin (and blood clotting in general), so they should not be used without prior medical clearance. A list of suspect herbs would include ginseng, garlic, ginkgo, dan shen (salvia), devil's claw, dong quai, fenugreek, horse chestnut, papain (from papayas), chlorella and St. John's Wort.

You can download an extensive list of foods containing vitamin K at tinyurl.com/z92bfl7. This list comes from the coumadin.com website, which includes other pertinent information about the medication.

There are also a number of cookbooks that may help. One I am familiar with is appropriately named "The Coumadin Cookbook," now in its fourth edition. The author is a medical doctor who wrote the book after his wife was put on Coumadin, and they faced the same problems that you are now experiencing.

Your partner has been given the remarkable gift of a new heart valve -- something that would not have even been possible years earlier. If all that's needed to make it work is to watch the foods he eats, so be it! I wish you both good health and good luck.

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.