Many years ago, I took a holistic nutrition course that taught me a lot about, well, holistic nutrition. The textbook, Dr. Elson Haas' Staying Healthy With Nutrition, was very informative (at over 1000 pages) and I read almost all of it.
Although I knew quite a bit about vitamins, minerals and enzymes before taking the course (I was totally fascinated with Earl Mindell's Vitamin Bible when I was a teenager), Dr. Haas' book provided much more detailed information about supplements, and new information (to me at least) about everything from different types of water to horrifying details about common food additives (such as coloring agent Red #3).
One of the concepts I learned about in the course is the idea of eating in-season foods. That means eating produce that is available and grown locally, preferably organically (but not necessarily). Prior to the holistic nutrition course, I never really thought about anything like that. But since you can't un-know what you know, I often wonder why it never occurred to me that those of us in Southern California (especially those of us surrounded by citrus trees and places named "Valencia" and "Orange County") are offered oranges from New Zealand when we go to the grocery store. Or farmed shrimp from Thailand, for example, when we're right here by the Pacific ocean.
There are many articles and other sources that will explain why eating seasonal foods is a great choice for your health (the food is cleaner, fresher and more nutritious), your pocketbook (those strawberries are more abundant and therefore less expensive when locally grown and in season), your local economy (you're supporting local farmers) and the environment (organic food and food that doesn't have to be shipped and stored has less chemicals than those oranges sent over here from New Zealand).
Obviously organic produce will be more expensive than the conventionally-grown stuff. If cost is a major factor for you when choosing the type of produce you buy, you can still choose in-season and/or local produce as a more healthful option if you can't afford to buy organic. Another possibility to consider is avoiding conventionally-grown produce on EWG's (Environmental Working Group's) "Dirty Dozen" list. Every year, EWG posts a list of the twelve produce items that are the most laden with pesticides. Strawberries made the top of the list for 2018 (therefore, choose to buy organic strawberries if you can afford them).
See the Dirty Dozen list for 2018 here.
The other list is called the "Clean Fifteen", also created by EWG. Each year, this list shows the fifteen produce items least likely to be contaminated by pesticides.
See the Clean Fifteen list for 2018 here.
Finding local, in-season produce can be easy to find in some places and more difficult to obtain in others. Hopefully, you can find an attractive selection of seasonal produce at your farmers' market or natural foods store. Another option is to sign up for a weekly, bi-weekly or monthly box from a CSA (Community-Supported Agriculture). The Local Harvest website can help you find a CSA near you.
The photo below is from one of my boxes from Hello Harvest. You can find their website here.
One of my boxes from Hello Harvest, a local CSA.
If a local farmers' market or CSA isn't an option for you, you can still begin to incorporate these healthful foods by choosing wisely at the grocery store, as described above.
The Produce Geek website will tell you what's in season for both organic and conventionally-grown produce.
The link below has a seasonal food guide that will help you determine the produce that is in season in your local area right now. (The link will likely default to California, so just use the pull-down menu to choose your state if you don't live here.)