MvcSiteMapProvider Roles

In this case "Admin" is the authorized user.

Add to web.config

<appSettings>
    <add key="MvcSiteMapProvider_SecurityTrimmingEnabled" value="true"/>
</appSettings>

Add to (change in) module - MvcSiteMapProviderModule.cs

bool securityTrimmingEnabled = true;

In Controller (above the action you want to constrict)

[Authorize(Roles = "Admin")]

In Mvc.sitemap

<mvcSiteMapNode title="$resources:Common,AccountTitle" controller="Account" action="Index" roles="Admin"/>