Swallowing the foreskin: [Achronim]

There are barren women who are accustomed to swallow the circumcised foreskin after dipping it honey as a Segula for having children.[1] The Poskim[2], however, vehemently opposed this custom and it is to be abolished.

[1] Sefer Mareh Hayeladim Mareches Hei Os 10; Custom recorded in Machaneh Yisrael 84, Rashbash 518; Yifei Mareh p. 240

The reason for its allowance: As some Poskim [Raavad Machalos Assuros 2:3; Ran Kesubos 24b; Ramban Vayikra 11:3 and Chidushim Kesubos 60b; Rashba Teshuvah 1:364, 3:257 and Chidushim Kesubos 60b; Implication of Tosafus Kesubos 60a; Rosh Kesubos 5:19, although is Rabbinically forbidden to cut off body and eat in his opinion; See Taz Y.D. 79:3 in opinion of Rosh; Peri Chadash 79:6 in opinion of Michaber and Tur who omitted the prohibition, and so is his conclusion Lehalacha; See Rashbash ibid] rule that there is no prohibition against eating human flesh. [Machaneh Yisrael 84]

[2] Shulchan Gavoa 79:7; Machaneh Yisrael 84; Rashbash 518; Machazik Bracha 79:2; Zivcheiy Tzedek 79:15; Darkei Teshuvah 79:15; Ben Ish Chaiy Emor 2:5; Kaf Hachaim 79:12; Sova Semachos [Y. Yosef] 2:8 footnote 15; 60:15; Otzer Habris Shaar 3 chapter 3:13; Sefer Rafael Hamalach; Or Torah Vol. 398:38

The reason: As a) One is required to bury the Arla in earth. [Michaber Y.D. 260:10; Tur 265; Beis Yosef 265; Pirkei Derebbe Eliezer 29; Targum Yonason Bamidbar 23:10; Baal Haturim Bamidbar 23:10; Zohar Lech Lecha 91a; Yireim 402; Hagahos Maimanis Mila 3:5; Rikanti 599; Rokeiach; Ittur; Hamanhig; Or Zarua; Abudarham; Rashal Yevamos 8:4; Levush 265; Shelah Chulin 91 in name of Tolas Yaakov; Tzeror Hamor Lech Lecha and Ki Seitzei; Hagahos  Maharash Vital Shaar Mamarei Chazal Shabbos 2; Sefer Bnei David Tazria 9; Nehar Afarsimon O.C. 27; Otzer Habris 3:15-22; Pesakim Uteshuvos 265:25] b) Some Poskim rule that it is Biblically forbidden to eat human flesh. [Rama 79:1; Darkei Moshe 79:2; Bach 79; Rambam Machalos Assuros 2:3; Maggid Mishneh on Rambam ibid; Ritva Kesubos 60a; Ran Kesubos 60a; Reah, brought in Shita Mekubetzes Kesubos 60b [transgresses Biblical negative command]; Taz Y.D. 79:3; Shach Y.D. 81:3; Kneses Hagedola 79:5; Lechem Chamudos 79:1; Erech Hashulchan 79:1; Peri Toar 79:3; Karban Aron Shemini; Ben Ish Chaiy Emor 2:5; Kaf Hachaim Y.D. 79:9; and 12; Halichos Olam 6:221; Malbim Vayikra 11:4]