[gb2world]

I suspect you can't set the variable inside modules/Extra_Fields/product.tpl and it will be applied globally. If you can keep the setting of the variables inside product.tpl - you should be able to use the variables inside the nested templates. To have the variables available globally - I think you would have to set variables in the php files. But before doing that, maybe this will work for you:

At the top of skin1/customer/main/product.tpl - before you call any templates:
Set all the variables:

{section name=field loop=$extra_fields}
{if $extra_fields[field].field eq "Ingredients" && $extra_fields[field].field_value ne ""}
  {assign var="ingredient" value=$extra_fields[field].field_value}
{/if}
{if $extra_fields[field].field eq "test exf A" &&  $extra_fields[field].field_value ne ""}
  {assign var="exfa" value=$extra_fields[field].field_value}
 {/if}
{if $extra_fields[field].field eq "test exf B" &&  $extra_fields[field].field_value ne ""}
  {assign var="exfb" value=$extra_fields[field].field_value}
 {/if}
{/section}

Then, you should be able to use the variables you set above later inside product.tpl and modules/Extra_Fields/product.tpl

<b>Ingredient:</b> {$ingredient}<br />
<b>Extra Field A:</b> {$exfa}<br />
<b>Extra Field B:</b> {$exfb}<br />