coffee-cupHampir setiap sudut kota sekarang sudah dipenuhi dengan mall. Masyarakat kita, terutama remaja, lebih sering menghabiskan waktu senggang di mal. Mall memiliki tempat-tempat yang dapat digunakan para remaja untuk berkumpul dan mengobrol bersama teman sebayanya, seperti kafe kopi. Bahkan dalam satu mal bisa terdapat beberapa kafe kopi, yang merupakan cerminan semakin banyaknya penikmat kopi di Jakarta.

Maka dapat kita lihat, sekarang banyak remaja dan dewasa muda yang semestinya tidak membutuhkan kopi mulai mengkonsumsi kopi. Hanya sekedar iseng minum sambil mengobrol. Sasaran kafe kopi pun berubah dari orang tua menjadi para remaja dan dewasa muda.

Menurut data yang diambil dari kafe kopi terkenal, secangkir kopi memiliki kadar kafein bervariasi antara 100-180 mg. Sedangkan kadar kafein yang baik dalam tubuh kurang dari 500 mg per hari. Apabila mengkonsumsi berlebihan (> 10 gram atau > 6 cangkir) dapat berakibat fatal. Jadi wajarnya, seseorang minum kopi 1-3 cangkir per hari.

Tapi itu tidak berarti kita boleh minum kopi 3 cangkir sekaligus. Karena hampir seluruh kafein dalam kopi yang kita konsumsi dapat diserap dengan cepat oleh saluran pencernaan. Kadar kopi yang meningkat drastis dapat menyebabkan gangguan kesehatan, seperti jantung berdebar, gelisah, insomnia (sulit tidur), gugup, tremor (tangan bergetar), bahkan mual sampai muntah-muntah.

Sebenarnya kafein adalah protein yang tidak diperlukan tubuh. Namun, tetap memiliki efek baik dan buruk bila dikonsumsi. Berikut akan dijelaskan lebih lanjut tentang efek dari kopi dan kafein yang terkandung di dalamnya.

Menurut penelitian di Amerika Serikat, kopi mengandung antioksidan yang paling besar di antara semua buah-buahan dan sayur-sayuran. Anti oksidan adalah zat yang dapat membantu tubuh untuk membuang zat-zat radikal berbahaya bagi tubuh. Zat radikal merupakan molekul perusak sel-sel serta DNA (cetak biru dari sel terkecil makhluk hidup). Sehingga, anti oksidan dapat melindungi seseorang dari terkena penyakit kanker atau jantung. Hasil penelitian memperlihatkan kopi dapat mengurangi resiko terkena kanker hati dan usus, diabetes mellitus tipe II serta penyakit Parkinson.

Selain itu kafein dalam kopi dapat menimbulkan perangsangan terhadap susunan saraf pusat (otak), sistem pernapasan, serta sistem pembuluh darah dan jantung. Rangsangan ini timbul akibat dilepasnya katekolamin yang dapat meningkatkan kerja dan denyut jantung sehingga dapat meningkatkan tekanan darah. Makanya, setiap kita minum kopi dalam jumlah wajar, tubuh terasa segar, bergairah, daya pikir lebih cepat, tidak mudah lelah atau pun mengantuk.

Karena efek-efek tersebut, banyak pelajar yang menggunakan kopi sebagai “senjata” untuk belajar. Hal ini memang menguntungkan apabila mempelajari ilmu sosial dan hapalan. Sebaiknya seseorang yang ingin memanfaatkan efek kopi tersebut meminum kopi setengah atau satu jam sebelum mulai belajar. Sebab kadar kafein dalam tubuh mencapai kadar tertinggi dalam waktu 30-60 menit setelah kita mengkonsumsi kopi. Tetapi efek-efek dari meminum kopi ini tidak begitu baik bagi seseorang yang pekerjaannya memerlukan ketelitian, kerapian, serta ketepatan menghitung, seperti matematika, menggambar atau melukis.

Kafein juga dapat meningkatkan aliran darah ke ginjal yang mengakibatkan produksi urin bertambah. Jadi, jangan heran kalau tak lama sehabis mengkonsumsi kopi, kita jadi lebih sering buang air kecil. Lebih jauh lagi, kafein ternyata dapat menetralisasi asam lemak dalam darah.

Sayangnya, kopi dapat menyebabkan efek kecanduan baik secara fisiologis maupun psikologis. Tanda-tanda seseorang sudah kecanduan minum kopi antara lain rasa letih atau lelah, tak bersemangat dan mengantuk kalau sehari saja tidak minum kopi.

Kafein juga bisa berbahaya pada lambung yang kosong. Dalam keadaan normal, lambung akan mengeluarkan berbagai zat sekresi lambung seperti HCl (asam klorida) dan pepsin apabila mendapat rangsangan protein dari makanan. Pada konsumsi kafein, pengeluaran zat dari lambung ini akan bertambah, meskipun tidak ada makanan yang ada di lambung. (Ingat, kafein sendiri adalah protein!) Ini dapat menyebabkan iritasi pada lambung dan usus duodenum. Sehingga dapat memperbesar risiko penyakit lambung, tukak lambung, atau tukak usus halus.

Pada konsentrasi yang tinggi (0,5 - 1 mmol), kafein dapat menghambat penarikan dan penyimpanan kalsium pada otot. Padahal saat remaja, kita membutuhkan banyak kalsium untuk pertumbuhan tulang dan gigi. Ini dapat menyebabkan osteoporosis di masa tua. Tidak hanya itu, kopi juga dapat meningkatkan risiko penyakit jantung dan pengerasan dinding pembuluh darah arteri (arteriosklerosis).

Waktu paruh kafein (waktu yang dibutuhkan supaya kadar kafein menjadi separuh dari kadar tertinggi) sangat bervariasi. Tergantung kondisi fisik dan kebiasaan merokok seseorang. Semakin buruk keadaan fisik atau semakin sering merokok, maka waktu paruh kafein di dalam tubuh juga semakin meningkat. Waktu paruh yang meningkat berarti metabolisme kafein semakin lambat dan efek kopi bertahan lebih lama pada tubuh.

Jadi, putuskan sendiri, butuh tidak kita minum kopi...?

Kepustakaan

Sherwood Lauralee. Human Physiology From Cells to System 5th ed . Thomson Brokson 600

http://www.depkes.go.id

http://www.detik.com

http://www.starbucks.com

http://www.emedicine.com/

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