Isoflavones’ Role in Functional Foods

September 2001

Isoflavones’ Role in Functional Foods

By Gary Brenner
Contributing Editor

The June 2000 issue of the American Journal of Clinical Nutrition (AJCN) reports that functional foods include “any modified food or food ingredient that may provide a health benefit beyond that of the traditional nutrients it contains.” It would also be helpful to make a distinction between dietary supplements (capsules, tablets, sachets) and functional-food products (health foods) as subcategories of the all-encompassing term “nutraceuticals.” The latter has been defined as “any food or part of a food that offers a medical or health benefit — including the prevention or treatment of disease — above and beyond simple nutrition.”

Recently, soy isoflavones have become a flagship of the nutraceuticals industry, with an important stake in this public health debate. Witnessing the dynamics of the Third International Symposium on the Role of Soy in Preventing and Treating Chronic Diseases, held in November of 1999 in Washington, D.C., a colleague and pharmacologist compared the exchange among the attendees — 450 researchers and nearly 100 representatives of industry and legislative bodies — to a heated debate over life-and-death issues in the Israeli Knesset (Parliament). Respected scientists revert to street language on topics such as good/bad protocols, analytical methods and conclusive findings. Thousands of published and ongoing clinical studies — epidemiological, in vitro and in vivo — seem to guarantee that isoflavones are not just a nutritional fad, but here for the long-term as a principal source of health benefits.

All about isoflavones
Soy isoflavones are naturally occurring plant chemicals belonging to the phytoestrogen class. They are currently heralded as offering potential alternative therapies for a range of hormone-dependent conditions, including cancer, menopausal symptoms, cardiovascular disease and osteoporosis.

Because isoflavones are of dietary origin and are extensively bio-transformed in the intestine by the action of bacterial enzymes, it is perhaps more accurate to define these bioactive non-nutrients as dietary estrogens, according to the article, “Phytoestrogens: The Biochemistry, Physiology, and Implications for Human Health of Soy Isoflavones” published in a 1998 issue of the AJCN. However, predicting the effects of isoflavones in vivo is more difficult because of the route of administration, chemical form of the phytoestrogen, its metabolism, bioavailability, etc.

Part of the controversy surrounding soy isoflavones is twofold: first, a tendency to tout them as “miracle treatments” due to the enormous amount of research being done in such diverse areas and, second, the fact that the largest body of research is on soy flours and isolates (including some isoflavones) or on the active ingredients genistein and daidzein, in pure form.

In fact, we only are beginning to see clinical research on commercial isoflavone products. Here lies the crux of the consumer-manufacturer-supplier triangle, along with the challenges presented by legislative bodies. Investing large amounts of research money in a plant extract that may be put on a shelf today and taken off tomorrow doesn’t make commercial sense. Sadly, more money often is put into advertising than into science.

Because isoflavones already have achieved a reasonable amount of credibility, consumers, manufacturers and raw-material suppliers can and should join together to guarantee the highest levels of science that the dietary supplement/functional food sector can afford. Examples of clinical trials on specific health issues using commercial products include:
• a study on the effect of 26 weeks of supplementation with a preparation on bone density in apparently healthy postmenopausal women;
• phytoestrogen dietary supplementation in obese, Type II diabetic, postmenopausal women, and its effects on endogenous estrogens and indices of cardiovascular risk;
• effect on non-invasive biomarkers of bone turnover, mood, memory and menopausal symptoms in healthy menopausal women;
• effects of soy-phytoestrogen extract in two forms — regular and slow release — on symptoms and on biophysical and metabolic variables of postmenopausal women; and
• an assessment of the plasma concentrations and pharmacokinetics of a new soy-isoflavone supplement in its regular and slow release forms.

During the course of this year, all these studies will be performed on commercially available 40% soy isoflavone concentrates, either as a single ingredient or as a compound (e.g., on bone density together with calcium, magnesium, zinc, and vitamins C, D and K).

Maximizing benefits
Industry can and should cooperate to discover the synergistic properties of the products being promoted. An example of this is a natural cereal bar fortified with soy isoflavones, lycopene and vitamin D. One retail soy-isoflavone beverage boasts 24 herbs and 29 vitamins and minerals. Whether consumers are eating a functional food or taking a dietary supplement, inevitably these are not single-ingredient products. It is the combined effect that is going to make consumers feel (or not feel) better, and it is the brand name that must meet the ultimate test.

Undoubtedly, we are all different. Not only do foods taste differently to each of us, they may affect us in distinct ways. Therefore, at the end of the day, we — the consumer — must take responsibility (with the advice of our physicians) to do well for our bodies.

Speaking of soy
Industry, manufacturers and raw material suppliers also need to address standardization, analytical methods and safety issues. This begins with the raw-material supplier.

An open dialogue between the raw-material supplier and the manufacturer is simply good business practice. Today, pressured R&D departments receive hundreds of natural plant-extract submissions. The recent food science graduate often is entrusted with getting new products into the market quickly and at as little cost as possible. There is little time, or room, for mistakes. Here are two brief examples of the kind of dialogue that can and should take place between partners in industry:

Q: A consumer question has come up in regards to the soy we purchase from you, and I am hoping you can help me out. Do you have any information regarding the vitamin K content of this material? Typical analysis information is sufficient. If you have never tested it, that response is fine as well.
A: I have looked through the literature and find that although vitamin K is found in soybeans, it is apparently only in very small quantities. In addition, vitamin K is oil-soluble and as a result most probably would be removed with the oil fraction at an earlier stage of processing. Consequently, it will appear as a minor component in the isoflavone fraction.

And:
Q: I would like to know the correct compound names for labeling purposes. Would it be correct to state that ‘S-40’ contains 40% isoflavones as genistein, daidzein and glycitein or genistin, daidzin and glycitin? Is 70% of this genistein or genistin?
A: ‘S-40’ contains 40% isoflavones expressed in the glycoside and aglycone forms. The product contains both genistin/genistein, daidzin/daidzein and glycitin/glycitein. The majority of the isoflavones (greater than 90%) are in the glycoside form, with the remainder being in the aglycone form. Because both forms appear in the product, the correct way to label the isoflavone is to include both forms or simply to state that they appear as both glycosides and aglycones, if you do not want to write the full list. The 70% that you refer to is the percentage of the total isoflavones that are in the genistein and genistin forms (the rest are the daidzin-daidzein, glycitin-glycitein forms).

Finally, there is the production process itself. Different dietary supplement/food manufacturers have different kinds of equipment. One may require higher bulk density and the other, granulated particles. There are formulations that from a cost point-of-view can afford lower concentrations of soy. Others have so little space in the capsule that only a higher concentration will work. Many plant extracts tend to have a bitter taste profile, requiring flavor masking without increased cost.

Successful soy
For any nutraceutical product to be successful, it must meet four consumer demands: taste, convenience, simple proposition and price. Some manufacturers will look only at price and the advertising support given by the supplier. In fact, in this world of natural plant extracts, there always will be a source for cheaper raw materials.
Not belying the importance of price, there are other factors to take into consideration, such as good science, good documentation, good technical support and the flexibility to offer a natural raw material that can be processed readily by manufacturers.

The nutraceutical industry will continue to grow quickly in the coming years. To guarantee this growth, the concept of “partnering” should be extended to include the critical components for making “healthy products” healthful.

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