Nutraceutical Testing

The development and introduction of functional foods or nutraceuticals has expanded rapidly in recent years. An increased development activity in functional foods followed the passage of the Dietary Supplement Health and Education Act (DSHEA) in 1994. This act set up a new framework for Food and Drug Administration (FDA) regulation of dietary supplements. In passing DSHEA, Congress recognized that many people believe dietary supplements offer health benefits and consumers want a greater opportunity to determine whether supplements may help them. The law gave dietary supplement manufacturers freedom to market more products as dietary supplements and provide information about their products’ benefits. The greater regulatory freedom in the dietary  supplement area in turn prompted a greater use of nutraceuticals in food products.

The term nutraceutical is used to refer to everything from traditional vitamins and minerals to products which contain amino acids, metabolites, extracts, concentrates, and botanical derivatives. Since these products are being used for health reasons, the pressure is great to ensure that they are pure, safe, and effective. However, the testing and analysis of these ingredients can vary greatly among companies. Adding to the testing pressure, the analysis, themselves, may be used as a means to differentiate retail products in a very competitive market.

One major contrast between how food additives and dietary supplements are regulated is that, although federal law requires manufacturers of dietary supplements ensure that the products they put on the market are safe, dietary supplement manufacturers do not have to provide information to FDA to get a product on the market. This is unlike the food additive process often required of new food ingredients. FDA review and approval of supplement ingredients and products is not required before marketing. Food additives not generally recognized as safe must undergo FDA’s premarket approval process for new food ingredients. This requires manufacturers to conduct safety studies and submit the results to FDA for review before the ingredient can be used in marketed products.

FDA’s primary interests regarding these products include ensuring that they are safe and properly labeled, as well as ensuring that health claims are based on valid scientific evidence. Regulations pertaining to nutraceuticals are constantly changing as various regulatory initiatives become more definitive with new test information and data guidelines.

Botanicals. Hundreds of botanical ingredients are now being used in foods and beverages. Many of these ingredients do not have a history of use in the U.S. Processors need to certify and ensure that an ingredient is what it purports to be, is not adulterated, and is not contaminated with pesticide residues or other impurities. Validated methods for many of these products have now been established. Although gas chromatographic and spectro-photometric methods are used, high performance liquid chromatography (HPLC), with its precision, speed, and specificity, is the current method for most of these assays. Mass Spectrometry (MS) and Evaporative Light Scattering Detection (ELSD) have also been used to analyze some of these herbs in foods.

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Vitamins. Many foods are fortified with both natural and synthetic forms of vitamins. Although many new methods and instrumentation are being used for the determination of vitamins, traditional wet chemistry and microbiological methods are still the method of choice. HPLC is the most popular technique for determining water-soluble vitamins.

Carbohydrates. As the interest in the health benefits of specific carbohydrates has increased, the specificity of the analytical methodology has also progressed. HPLC, flow injection analysis (FIA), and enzymatic assays are used for the determination of carbohydrates.

Isoflavones. Isoflavones are a class of chemical compounds found in a variety of plants, with high levels found in soybeans. Studies report that isoflavones may inhibit certain cancers, lessen symptoms of menopause, and can contribute to improved bone density in treatments for osteoporosis. Three parent isoflavones are found in soy along with corresponding glucosidic forms and ester derivatives of the glucosidic forms. Methods reported for determining isoflavones include a variety of extraction techniques followed by HPLC for separation and UV or mass spectrometry for identification and quantitation.

Carotenoids. Carotenoids are highly conjugated pigments which include the carotenes (hydocarbon carotenoids) and xanthophylls (oxygenated carotenoids). These pigments are found in foods and are also added as food colorants and nutritional supplements. Identification and analysis of carotenoids may present challenging problems. UV-VIS spectrophotometric measurements are commonly employed for estimating total carotenoids; however, HPLC methods are used to measure individual carotenoids. Electrochemical detection (ECD) has emerged as a useful alternative to conventional (UV-VIS) HPLC methods where high sensitivity is necessary for very small sample sizes or trace analysis.

Tocotrienols. Tocotrienols are members of the vitamin E family. Commercial products are concentrated extracts from rice bran and palm oils. They contain both tocotrienols and tocopherols. In addition, they contain other components such as glycerides, terpenes, squalenes, sterols, free fatty acids, and others. HPLC may be used for simultaneous determination of tocopherols and tocotrienols in oils, extracts, and concentrates.

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Anthocyanins. Anthocyanins are red to dark blue color pigments found in plants. Identification and quantitation of these pigments are well established in the food industry because of their importance to food color quality. However, interest in their accurate analysis has increased because of their possible health benefits in foods. Determined spectrophotometrically, there are no standard, universally accepted protocols regarding nomenclature and extraction procedures. Total anthocyanin content may be measured with the pH differential spectrophotometric method while HPLC with external standard quantitation is an alternative. Additional spectral procedures provide indices for polymeric color and browning. Reverse phase HPLC with a UV-VIS diode array detector is the method used for determining qualitative changes.

Glucosinolates. Glucosinolates are an interesting group of compounds found in plants such as cabbage, broccoli, mustard greens, radish, and others. They are responsible for the flavor of some foods (mustard and horse-radish) and may also play a role in cancer prevention. On the other hand, they are known to interfere with the thyroid and to damage vital organs. There are various direct and indirect methods for measurement of total or individual glucosinolates in seeds including the glucose release method, the palladium method, near infra-red (NIR) spectroscopy, X-ray fluorescence, GLC, and HPLC. HPLC of desulfated glucosinolates is now the reference method.

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by JAMES GIESE
Internet Editor