In a study of healthy subjects grouped by age (Younger: 19-50 years, Seniors: 65-75 years, and Longeval: 85-102 years), Herrmann et al. (A-8) measured their vitamin B-12 levels (ng/L). All elderly subjects were living at home and able to carry out normal day-to-day activities. The table shows vitamin B-12 levels for 50 subjects in the young group, 92 seniors, and 90 subjects in the longeval group.

\fYoung (19-50 Years) Senior (65-75 Years) Longeval (85-102 Years) 300 314 375 137 525 1192 460 400 1270 262 230 254 229 452 298 748 548 348 252 161 215 419 193 437 153 187 198 175 262 1113 260 335 294 236 323 350 165 540 381 409 349 455 740 432 205 1365 226 293 162 378 315 297 194 411 248 232 557 196 340 203 257 456 780 268 371 509 166 632 370 221 536 668 245 703 668 357 218 438 483 917 582 240 258 282 197 201 186 368 222 244 293 320 419 290 260 177 346 262 277 569 562 372 286 198 872 239 190 226 325 360 413 143 336 240 241 203 275 357 685 310 421 136 195 369 172 609 136 352 712 359 220 162 2000 740 441 262 461 715 164 95 240 430 423 404 631 252 279 178 235 645 617 380 1247 414 297 530 284 395 985 322 1033 372 474 334 883 302 170 340 285 236 375 521