First, you're going to have to spend some time researching your targets. You can go for the typical outlets that feature startups, but I think you'll find great traction if you start researching bloggers that are in the healthy food space.
I would also spend some time researching who has covered your competitors, who might be healthy snack subscription services such as Urth Box, Healthy Box, Graze, etc. You can use a tool like Buzz Sumo (buzzsumo.com) to see what publications and AUTHORS (this is the most important part) have covered their launch or anything related to them.
The authors are extremely important because often times they have their own personal blogs, or they write for multiple places. Once you find the authors you want to target, get to know them and engage with them. I have a lot of tips (and also a research spreadsheet as a resource) that you can find in these two places:
Resource For Research/Tracking: http://t.co/89AER7pUBW
As far as an example email, something like this might work for a food blogger, customized for each person and in your own voice. Never, ever send the same exact pitch to food bloggers, and make sure you research their temperament before reaching out. You'll want to get to the point, but make sure they know that you appreciate their blog, them, and what they've written about. Also, make sure you're following them on their various networks and that you've engaged in some way with them. This may take some preparation but it's worth having that warm touch before reaching out.
Also make sure they're open to accepting pitches. Some explicitly state that they're not, and you should honor that.
---Hi [name] <-- always address by name.
I'm [your name] and I'm the founder of [company name], which is a healthy snack food subscription service. We [name competitive differentiator here] and I'm hoping to help spread the news of its launch to the food community. I was looking through your blog/site/publication and I noticed that you've posted about [something related to your area - healthy snacks, healthy recipes, quick bites, etc - share link] and [share why it was important to you - maybe their post talks about one of the reasons you decided to launch the company, etc].
Do you feel as if [company name] would be a good fit to share with your audience? We'd love to share a promotional code with your readers so that they're able to get the first month free and test out the snacks.
Thank you so much for your time! ----
As far as reaching out to bloggers that have covered competitors, that's another beast, because you have to be respectful in how you approach it.
If you have the resources, you can always write a post that discusses something in the health space related to food, including (proven) scientific facts, with visual "fact cards" that can then be pitched to a bigger news outlet. That's just a very loose, general example as more research is required to figure out what will resonate with that crowd. It's also something that I could brainstorm and cover in depth on a call. I'm always available to chat via Clarity. I've executed outreach for a lot of product launches in the past and I'm happy to chat about this.
Have a great day!