Williams A C, Ramsden D B
Division of Neuroscience, University of Birmingham, Edgbaston, Birminham B15 2 TT, UK.
Med Hypotheses. 2005;65(2):353-62. doi: 10.1016/j.mehy.2005.01.042.
Monkeys and man are very closely related genetically. Yet intellectually there are big differences and they suffer from a broad range of different diseases. For example, monkeys do not get Parkinson's or Alzheimer's disease. The former is surprising given that both get parkinsonism from MPTP poisoning and the latter initially less surprising as the cortex predominantly affected in Alzheimer's never developed as fully in the monkey. Man is an omnivore whilst other primates are predominantly herbivores. The one primate who was almost wholly carnivorous was Neanderthal man who became extinct. Red meat has a high content of Nicotinamide, Choline, and methyl donors. The enzyme NNMT converts nicotinamide to N-methyl-nicotinamide using SAM as the methyl donor. It is not present to any degree in herbivores. It has recently been shown to be present in human brain and up regulated in Parkinson's disease. Omnivores presumably need it for nicotinamide homeostasis but the production of N-methyl-nicotinamide will also be beneficial as it will reduce the export of Choline from neurones. Both will aid brain growth and development. However, as N-methyl-nicotinamide resembles MPTP it could cause parkinsonism later in life for man but not monkeys as they would be predicted not to have as much NNMT. Humans with a diet low in Nicotinamide,Choline or methyl donors early in life and low enzyme activity may be prone to Alzheimer's as their brain and therefore its reserves may never have developed as fully. The possession of NNMT plus a diet rich in Nicotinamide, Choline and methyl providers may explain many of the advantages but also the disadvantages of the human condition. One prediction is that a diet rich in these micronutrients whilst young will improve brain development and reduce the risk of Alzheimer's but that a lower dose later in life will reduce the risk of Parkinsonism. A second prediction is that it will become clear that dietary factors including vitamins are signalers and at the head of vital biochemical pathways. A time point will be reached when errors emerge that could not be deleted by evolutionary pressures. Finding and rectifying them will be the key to preventing many common diseases.
猴子和人类在基因上密切相关。然而，在智力方面存在很大差异，并且它们患多种不同疾病。例如，猴子不会患帕金森病或阿尔茨海默病。鉴于两者都会因MPTP中毒而出现帕金森综合征，前者令人惊讶；而后者最初不那么令人惊讶，因为在阿尔茨海默病中主要受影响的大脑皮层在猴子中从未充分发育。人类是杂食动物，而其他灵长类动物主要是食草动物。几乎完全食肉的一种灵长类动物是已灭绝的尼安德特人。红肉富含烟酰胺、胆碱和甲基供体。NNMT酶利用SAM作为甲基供体将烟酰胺转化为N-甲基烟酰胺。它在食草动物中不存在。最近发现它存在于人类大脑中，并且在帕金森病中上调。杂食动物可能需要它来维持烟酰胺稳态，但N-甲基烟酰胺的产生也将是有益的，因为它将减少胆碱从神经元的输出。两者都将有助于大脑的生长和发育。然而，由于N-甲基烟酰胺类似于MPTP，它可能在人类后期导致帕金森综合征，但对猴子不会，因为预计它们没有那么多NNMT。早年饮食中烟酰胺、胆碱或甲基供体含量低且酶活性低的人可能易患阿尔茨海默病，因为他们的大脑以及因此其储备可能从未充分发育。拥有NNMT加上富含烟酰胺、胆碱和甲基供体的饮食可以解释人类状况的许多优点和缺点。一个预测是，年轻时富含这些微量营养素的饮食将改善大脑发育并降低患阿尔茨海默病的风险，但在生命后期较低剂量将降低患帕金森综合征的风险。第二个预测是，将清楚地表明包括维生素在内的饮食因素是信号分子，并且处于重要生化途径的首位。将会达到一个时间点，那时会出现无法被进化压力消除的错误。发现并纠正它们将是预防许多常见疾病的关键。
