Functional foods — anyone?

In the Philippines, we have traditionally recognized that some foods have health benefits beyond nutrition. We often hear our elders advise the younger ones — eat this food; this is good for your health. For some time now, this kind of food has gotten a name, i.e., functional foods. Functional foods are defined as foods which, because of the presence of physiologically active components, provide benefits beyond nutrition.

Japan was the first country to recognize this class of foods and its Ministry of Health and Welfare created “Foods for Specified Health Use” or “FOSHU” in 1991. As of 2011, more than 1,000 products have been approved as FOSHU and bear the FOSHU seal. The market for FOSHU products was about 650 billion yen (P290 billion) in 2009. In the Philippines, no specific regulations exist for functional foods; claims are health and nutrition claims permitted under the Codex Alimentarius Guidelines (CAC/GL 23-1997) as stated in BFAD Circular 2007-002. Many countries refer to functional foods as foods with health claims.

Many scientific studies done locally and abroad show the nutritional and health benefits of common Philippine foods such as rice, coconut, legumes like mungbean and indigenous legumes, native vegetables like malunggay and ampalaya, root crops like sweet potato, greater yam and taro, and fruits like mango, papaya, banana and pineapple. 

Rice. Rice is the staple food of majority of Filipinos. Its functional qualities are due to its dietary fiber, lipid and nature of starch. Rice bran is rich in the B-vitamins, vitamin E, lipids, minerals and phosphatides. However, we usually eat white or polished rice. Milling of rice removes the bran, resulting in large losses of minerals, dietary fiber, especially insoluble fiber and phenolics. The antioxidants in rice bran include oryzanol, the tocopherols and tocotrienols. A product from rice bran called Tiki-Tiki is rich in thiamine and has been traditionally used to cure beriberi and is a popular vitamin drop for infants. Nowadays, brown rice is promoted as a health food. However, its relatively higher price makes it more of specialty rice. The Philippines also boasts of several pigmented rice varieties (red, violet and black) which have high antioxidant activities and dietary fiber. The high antioxidant activity could be due to the pigment as the purple Perurutong brown rice has 0.62 percent catechin compared to 0.07 percent for the milled counterpart. Some of the potential benefits of the functional components in rice include control of blood sugar due to its relatively high dietary fiber, the lowering of cholesterol due to the lipids, the high antioxidant and anticancer potential due to oryzanol, tocopherols and phytic acid in the bran, and antiberi-beri because of the high vitamin B content of the bran. The glycemic index (GI) of rice varies with variety; in general, waxy and low amylose rices have higher glycemic indexes than intermediate and high amylose rice varieties. Processing of rice like parboiling and noodle making will also reduce the glycemic index. 

Legumes. Among the legume grains, mungbean is perhaps the most popular in the Philippines. Mungbean contains 17–26 percent protein and is considered a major source of protein in developing countries and a good source of minerals and vitamins. Mungbean flour has 30 percent fiber (4 percent soluble and 26 percent insoluble) and has a low glycemic index. Sotanghon, the noodles from mungbean starch, has a relatively low glycemic index of 26–39.  Sprouts of legume grains are a popular form of vegetable among Asians. Sprouting of mungbean results in increased ascorbic acid content. When combined with biological, chemical and physical stress, it results in production of phytochemicals such as polyphenols which are important in chemoprevention. In addition, antimicrobial activities are stimulated in dark-germinated mungbean sprouts in response to various inducers. 

Our country has several largely unexploited indigenous food legumes, namely jackbean, swordbean, sam-samping, batao or hyacinth bean, sabawel, rice bean, lima bean, and pigeon pea. In addition to their uses as foods, most of these legumes have health values such as anti-allergenic effects, hepatoprotective activity, antidiabetic, antimicrobial, anticancer, etc. More studies should be conducted to determine functional attributes of these indigenous legumes toward their enhanced utilization.

Coconut. So many food products can be obtained from coconut: coconut water, fresh coconut meat, coconut milk, virgin coconut oil, copra oil refined to become vegetable oil, coconut flour and coconut protein. Coconut water is an excellent rehydration medium. It has been used to prevent formation of stones in the urinary tract and is now becoming a popular export product as a refreshing, health drink. 

The gata or coconut meat extract, also called coconut milk, contains proteins, oil, and other phytochemicals and is widely used in cooking with vegetables and meat. Dessicated coconut is about 69 percent oil while gata is 24 percent oil. Coconut oil has antimicrobial activity against bacteria, yeast, fungi, and enveloped viruses. Its major fatty acid, lauric acid, has antimicrobial activity and its monoglyceride has even higher activity!

Virgin coconut oil (VCO) has been cited for its health benefits. The antioxidant potential levels of VCO samples are comparable to a-tocopherol. Animal feeding tests of VCO showed reduction of total cholesterol, triglycerides, phospholipids, low density lipoprotein (LDL) cholesterol (bad cholesterol), and very low density lipoprotein (VLDL) cholesterol (ugly cholesterol) levels and increased high density lipoprotein (HDL) cholesterol (good cholesterol) in serum and tissues. Feeding of coconut protein resulted in lower levels of total cholesterol, LDL+ VLDL cholesterol, triglycerides and phospholipids in the serum and higher levels of serum HDL cholesterol. 

Another by-product of the coconut industry is coconut flakes or flour which consists of 60 percent dietary fiber (56 percent insoluble and 4 percent soluble). Glycemic index of foods supplemented with coconut flour decreased with increasing levels of coconut flour. In addition, feeding coconut flakes or flour to human subjects with moderately raised serum cholesterol (from 259 to 283 mg/dL) with 15 percent and 25 percent coconut flakes reduced serum total and LDL cholesterol and serum triglycerides of human subjects with moderately raised serum cholesterol.

Because of its high medium chain fatty acid content, coconut oil is easily absorbed and digested and is used as a therapeutic diet for convalescing patients.

Native vegetables. Malunggay is now widely cultivated and indigenized in tropical Africa, tropical America, India, Sri Lanka, Malaysia and the Philippines. Malunggay leaves have high antioxidant activity due to high vitamin A, B and C contents and niaziminin which has also been shown to have anti-tumor potential. A very strong, novel hypotensive principle has been isolated from malunggay. Malunggay protein is of good quality as its amino acid pattern is higher than that of the FAO standard. Its oil, called benoil, is odorless and does not become rancid and is edible.

Bitter gourd or ampalaya, is another very popular local vegetable with anti-diabetic effects and high antioxidant potential. It has been used as folk remedy for diabetes in several Asian countries. Edible portions of native vegetables such as eggplant, bitter melon, horseradish tree leaves, string long beans leaves, etc., have relatively high levels of antioxidants.

Root crops. Several commonly utilized root crops in the Philippines such as sweet potato, taro or gabi, greater yam or ube, and cassava have excellent dietary fiber content and are low glycemic index foods. The antioxidant potential of several varieties of greater yam, taro, sweet potato and taro are similar to or even higher than the control BHA and a-tocopherol.

Fruits. The major tropical fruits produced in the Philippines are mango, pineapple, banana and papaya. These are all established to have high contents of some vitamins, minerals and phytochemicals which make their intake beneficial to human health. In particular, these fruits are high in potassium, with banana and papaya having the highest contents of 358 and 257 mg percent. Papayas have very high levels of ascorbic acid (61.8 mg percent) followed by pineapple (36.2 mg percent) and mangos (27.7 mg percent). The four types of fruits contain the B-vitamins in varying concentrations. The red- or orange-fleshed papayas and mangos are also rich in vitamin A (1094 and 765 IU, respectively) and beta carotene (276 and 445 mcg percent, respectively).  Many other tropical fruits such as durian, mangosteen, jackfruit, etc. have become important sources of vitamins, minerals and phytochemicals. Green and ripe mango, and green and ripe papaya exhibit relatively high antioxidant activities. Further studies showed that whole mango juice and juice extracts have anticancer activity.

Processed food products. Nata de coco and achara or pickled grated papaya are examples of processed food products with functional attributes. Nata de coco has high dietary fiber while achara has high antioxidant activity. Fermentation processes have been shown to improve the health benefits of some foods. Fermented papaya is a major ingredient of a natural Japanese health food called Bio-normalizer which is manufactured in the Philippines. It has been shown to exhibit therapeutic properties against tumor and various enteropathogens.

What do we need to do? We have to conduct more researches on the functional attributes of Philippine traditional foods. And very importantly, we have to establish the recommended amount and frequency of intake of such foods needed to obtain the health benefits, information on which is sorely lacking. For example, eating about 60 g of oatmeal can achieve 5 percent reduction in serum cholesterol as shown by human feeding studies in the United States. Consumption of soy (25 g) results in significant reductions in total cholesterol, LDL cholesterol and triglycerides and a small but insignificant increase in high density lipoprotein cholesterol. We not have this kind of information for our native foods!

The government should also consider acknowledging functional foods as a class of foods and establish guidelines for them. The requirements for functional food classification can be patterned after those required of Japanese FOSHU products. These requirements are as follows: (a) scientific evidence for claimed health benefit is available; (b) clinical and nutritional intake level of the product and or its functional component is established; (c) it is safe for human consumption; (d) functional component is defined in terms of physical, chemical and biological characterization and can be qualitatively and quantitatively determined; (e) the food is intended to be consumed on a daily basis, not rare occasions; (f) the product or functional ingredient is not in the medical list.

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This article is based on the author’s review article “Development of functional foods in the Philippines” published in Food Science and Technology Research (Volume 13, pp. 179-186, 2007). A shorter and updated version was presented at the 62nd Annual Convention of the Philippine Association for the Advancement of Science last Sept. 12.

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Dr. Evelyn Mae Tecson-Mendoza is a member of the National Academy of Science and Technology Phl and professor emeritus of the University of the Philippines Los Baños. A biochemist, she served as chairperson of the Molecular Biology and Biotechnology and the BS Agricultural Biotechnology programs of UPLB before her retirement. She may be contacted at [email protected].