I need some help on port allocation. All my investments are in Vanguard mutual funds. I am 10 years away from retirement with assets of 1 mil in tax advantaged accounts. My current allocation is:

37% Total U.S.

35% International Growth

20% TIPS

5% Energy Index

3% Emerging Markets

I have only recently moved into TIPS. Up until this year, I've been totally invested in stock index funds since starting to save 25 years ago. My question is, is this enough diversification as I move closer to retirement? Also, is TIPS the best instrument for adding stability for stock fluctuations and if so, is the 20% allocation sufficient for 10 years out from retirement. I've lost 6% on the TIPS in less than a month, so I'm questioning the usefullness of this. At retirement, I'll move most of the assets into a fund aimed at providing income with aim at preserving capital, though not sure which one yet.

 I'd appreciate any and all comments or suggestions.