The general concept of consuming seasonal food involves eating that which is grown locally and harvested at peak season. During this time, the produce will naturally be at its freshest, as well as highest in both flavor and nutritional content.

While there are a few exceptions – beets, carrots, parsnips and radishes can be consumed almost any time of year – basic guidelines include eating cooling fruits and vegetables in the summer, balanced with warming fruits and vegetables in the winter, as well as consuming a frozen variation of whatever is desired out-of-season. There are some additional “golden rules” to be aware of, however, so as to maximise nutritional content, while minimising environmental harm.

FRUIT

1. Grapes – buy in season (late summer) with seeds: seedless cultivars now make up the bulk of grapes produced, even though the seeds contain most of the nutrients. The result is a loss in the potential health benefits provided by the enriched phytochemical content, such as resveratrol – a polyphenol antioxidant – which has been positively linked to preventing cancer, degenerative nerve disease, heart disease, and viral infections. Furthermore, imported grapes are to be avoided due to their thin skin and thus the increased chance of pesticide residue from countries with lower regulations.

2. Peaches – buy organic and in season (July or August): peach breeding has favoured cultivars that are firm, full of red color and have shorter fuzz on the surface. In an attempt to ease international shipping (out-of-season), as well as supermarket sales because of the “improved” appearance, the selection process has reduced flavor and nutritional content, as well as shortening the shelf life. In comparison, fresh organic peaches are high in vitamins A, C as well as beta-carotene.

3. Strawberries – buy organic and in season (mid-June to mid-August): commercial production has extended the strawberry season to cover mid-April to mid-December, when strawberries are either grown in greenhouses or heated plastic tunnels. Greenhouses are used to protect the crop from the elements, providing artificial heat and light; while plasticulture methods also need the soil to be fed with artificial fertilisers. Unfortunately, imported strawberries aren’t any better because they come from countries which have loose regulations on pesticide use.

4. Tomatoes – buy organic and in season (between early-August and mid-October): commercial cultivars have resulted from the breeding of tomatoes for factors such as shape and size, disease and pest resistance, suitability for mechanised picking and shipping, as well as an ability to be picked before fully ripening. In order to facilitate transportation and storage, tomatoes are often picked unripe and ripened in storage with ethylene. Unsurprisingly these tomatoes have poor flavor and nutritional content after being kept for months in storage, despite otherwise being high in vitamin A and beta-carotene.

5. Zucchini – buy organic and in season (July to September): although a vegetable in culinary terms, the zucchini is a fruit. Part of the summer squash family, zucchini is naturally high in fiber, potassium, as well as vitamins A and C, boosting the immune system and helping to maintain healthy eyes, heart, lungs and skin. Zucchini is now either grown in greenhouses or shipped large distances from countries where the farming method uses chemicals (fertilisers, insecticides and pesticides) as well as huge amounts of water.

VEGETABLES

6. Asparagus – buy in season (between May and mid- to late-June): asparagus is a spring vegetable that possesses a lot of nutritional qualities, with its stalks providing a good source of fiber; protein; vitamins A, C, E and K; as well as folic acid, iron and selenium. Out-of-season the stalks become bland, limp and woody, and lack nutrients. To increase commercial production asparagus is now grown in greenhouses alongside tomato plants, with the remainder imported.

7. Corn – buy organic and in season (late summer and early fall) or frozen: corn has a short season, peaking when its sugar content is at its highest. Commercial cultivations have been bred to produce disease resistant corn that is uniform in appearance, but lacks flavor and nutritional content. Furthermore, Monsanto’s Bt corn is flooding the market and has been genetically modified to resist certain insects. Whether fresh or frozen, it is important to consume non-GM and organic corn. When out-of-season, frozen corn is best.

8. Lettuce – buy in season (early spring) or alternatives: there are plenty of varieties of lettuce available in the stores, but despite the development of new packing, shipping and storage technologies to improve the lifespan of lettuce, it should only be bought locally. The best lettuce is obtained fresh at the point it achieves maximum level of crispiness, as well as sugar content. Out-of-season lettuce is imported from countries with little (or no) pesticide regulation, and as lettuce is highly absorbent it is one of the dirtiest vegetables. In fact, dependent upon the variety, lettuce can possess nutritional deficiencies, while also being a potential source of e-coli and salmonella. Lettuce alternatives include cabbage, kale and other leafy greens.

9. Mushrooms – buy organic, seasonal varieties: although mushrooms can be consumed all year, it is important to stick to the seasonal varieties, for example: morel mushrooms in the spring, lobster mushrooms in summer; chanterelles in the fall, and truffle mushrooms in winter. Mushrooms are a good source of B-vitamins, as well as essential minerals, but because they are highly absorbent, it’s best to avoid imported or non-organic varieties due to the potential residue of chemicals and toxins, coupled with low nutritional content.

10. Peas – buy in season (early spring) or frozen: much like corn, peas have an extremely short season. When in season for two weeks in early spring, peas have a high sugar (low starch) content, and are full of flavor, as well as nutritional value. Fresh peas provide fibre, protein, as well as important minerals and vitamins, in comparison to out-of-season peas that have a low sugar and high starch content, little flavor and no nutritional value unless bought frozen. Similar to corn, frozen peas have been frozen straight from the field when at their freshest and sweetest.