Tempeh and Isoflavone Benefits

This post is one part of my research proposal about Tempeh. I am interested in researching benefits of Tempeh because tempeh is one of most popular Indonesian food. It is relatively cheap and has many beneficial effects for health. Not much Indonesian people know the beneficial effects of tempeh. Hopefully this study will brings goodness for everyone.

Tempeh is Indonesian traditional food, which is made by fermented soybean. It is one of alternatives source of protein and relative cheaper than animal source of protein. The texture is soft and has a unique flavor. It uses Rhizopus oligoporus to ferment the soybean.

Basically, tempeh is made from soybean. In 100 grams of soybean, it contains protein almost 40%. Not only macro and micronutrients, soybean also contains isoflavone. Isoflavone is one of phytoestrogen which refers to plant-derived compounds that show estrogen-like biological activity. It is structurally and functionally similar to 17β-estradiol. There are three groups of phytoestrogen: genistein, daidzein, and glycitein (24).

Tabel 1. Nutrition composition in 100 grams of tempeh

Nutrients	Value per 100 g	Unit
Energy	201	kcal
Protein	20.80	g
Total lipid (fat)	8.80	g
Carbohydrate	13.50	g
Vitamin A	0.0	IU
Vitamin B1	0.19	mg
Vitamin C	0.0	µg
Calcium	155	mg
Iron	4.00	mg
Phosphorus	326	mg

 Source: Daftar Komposisi Bahan Makanan, 2013

Compared to unprocessed soybean, tempeh has higher protein efficiency (PER) ratio and vitamin B. Trypsin inhibitor and phytic acid in soybean also decreased in tempeh because of R. oligoporus fermentation (25). Fermentation in tempeh also increase the availability of isoflavone aglycones. Aglycone form is changed by hydrolysis of the isoflavone glucoside by β-glycosidase enzyme during fermentation process (26). Soy isoflavone has many beneficial effects to human health. Genistein, one of soy isoflavon, has anti-diabetic effects on β-cell proliferation, glucose-stimulated insulin secretion and protection against apoptosis, independent of its function as an estrogen receptor agonist, antioxidant, and tyrosine kinase inhibitor (27). Isoflavones are thought to exert both estrogenic and antiestrogenic effects, depending on the tissue. Isoflavones may block the estrogen receptor, thereby having an antiestrogenic effect on uterine and breast tissue where excess estrogen may promote tissue proliferation. Conversely, isoflavones may bind to the estrogen receptor and stimulate estrogen activity in other tissues, thereby having an estrogenic effect. It has been hypothesized that soy isoflavones exert a proestrogenic effect on menopausal (28). Soy food consumption is effective in relieving menopausal symptoms and it also associated with lowering risk of breast and endometrial cancer in observational studies (29).