First of all, hello!! Thank you for letting me join your community!

Here's my issue: I make homemade smoothies using eggwhite powder, fruits, almond milk and veggies. I know they are healthy and they really help me stay away from snacking on junk food in the mid-afternoon. But my SIL said she used slimfast in the same manner and prefers it because they add a bunch of vitamins and that, while my smoothie might be healthy, it's probably not as comprehensive in the vitamins that it has. Like, if I only put mango chunks and spinach in my smoothie, that wouldn't include as many vitamins as they put in slimfast.

Ok, I feel a little bit stupid letting her make me wonder if she's right, because I guess deep down I know there's no way her slimfast is healthier than my natural smoothies. But I AM kind of stupidly wondering if she's got a point. Should I at least add some sort of vitamin powder to my smoothies? What do you all think?

Keep your smoothie.

And take a vitamin tablet instead.

Job done.

Fresh is best.

Slimfast is comprehensive? Please do not make me laugh.

I get more protein from a single can of fish (and I eat 6 cans a day). My full allowance of most vitamins and minerals from a vitamin tablet (slimfast only provides some of what you need). And more dietary fiber from my oats, dried figs and Turkish apricots.

This is the only thing you said that matters.
If they work for you, stick with them!

Also, I agree with IanG: Fresh is best, and Slimfast isn't going to give you anything you can't get from a daily vitamin. Never mind that; Slimfast isn't going to give you anything you can't get from real food!

If you're logging your food in MyFitnessPal or something similar, you should be able to see what kind of vitamins you're getting from your food. But even if not, why not look up the vitamins and macronutrients for the ingredients in your smoothie? From the sound of it, your smoothie has some great stuff in it, and anyway, you're eating other food, right? So you're getting varied nutrients throughout the day.

Everyone's going to have advice for you. I spout out too much of it sometimes, myself - I think it's just something most people do. But be confident to listen to your own advice, too!