Vitamins work best in their groups. Whilst I agaree with what you are saying Kungfu I believe personally that it's a simplistic way of looking at our nutrition.

Our green leafy veges are depleted in folate, zinc and many other vitamins and minerals. This is due to farming techniques, the fact they are picked before they are ripened (often), the fact that they are refrigerated at low temps, transported great distances, long shelf life etc... If we grow our own veges organically, in rich soils, low pollutant area and pick then eat we would be eating high folate leafy greens. The fact that most of us are not leaves us at risk...
Also, cooking kills b vitamins.

Folate has been found to protect a high number of babies from developing neural tube defects. It has also been found in high doseage to be beneficial for preventing miscarriage. For folate to be beneficial it needs to be taken in a therapeutic doseage. Relying on an unmeasured doseage from dietary sources, I believe is risky.

Renstar: Yes, it's true that folate without b12 and b6 finds it difficult to be utilised by our bodies. For most women who don't have the issues that Willow and myself have the amount of b12 and b6 in a multivitamin is sufficient for absorption...

Of course this is my personal opinion, reasoned from much research and personal experience - each person has to decide for themselves after independent research what feels right for them...