Nutrition is a factor that longevity doctors and researchers often point to as the key to good health. When it comes to diet, some experts say prioritize antioxidants and add leafy greens to almost every meal. Others, on the other hand, specifically focus on reducing or avoiding entire categories like gluten and ultra-processed foods. And they often encourage their patients to do the same.
But Dr. Simon Feldhaus, who has 30 years of experience, about half of which has been researching longevity, takes a very different approach.
“I hate dieting. There’s too much discussion about dieting,” he told CNBC Make It.
Feldhaus is also president of the Swiss Association for Anti-Aging Medicine and Prevention and chief physician at the Swiss Hub of Balance Rehabilitation Clinics.
“Personally, I don’t think there is such a thing as a healthy diet,” he added.
At Feldhaus, we don’t follow a strict meal plan. Instead, he is intentional about where he sources his food to ensure it is of the highest quality possible. We also value seasonal ingredients.
“I only eat vegetables that are in season,” he says. “It’s almost autumn or winter now, and strawberries aren’t growing, so why should I eat strawberries?”
Registered dietitian Wendy Lopez told the American Heart Association in 2024 that the longer a crop is harvested until it is consumed, the more likely its nutritional content and value will decline. “Vitamins, especially vitamin C, degrade during storage, meaning apples that have been stored for several months may have lower levels of certain nutrients compared to freshly harvested apples,” Lopez said.
For a complete list of seasonal produce year-round, see the USDA’s SNAP-Ed Connection Seasonal Produce Guide.
If you’re wondering which fruits and vegetables to pick up the next time you go to the market or prepare for the holidays, here’s a quick list of what’s in season right now.
Season: Autumn
fruit:
Apple Banana Cranberry Grape Kiwi Lemon Lime Mango Pear Plantain Pomegranate Raspberry
vegetables:
Bell peppers Cruciferous vegetables such as broccoli, Brussels sprouts, cauliflower and radishes Celery Green beans Leafy greens such as cabbage, collard greens, kale, lettuce, spinach and Swiss chard Mushrooms Okra Onions Peas Potatoes Pumpkins Root vegetables such as beets, carrots, parsnips, rutabaga and turnips Sweet potatoes/yams Winter squash
Season: winter
fruit:
Citrus fruits such as apples avocado bananas lemon, lime, orange, and grapefruit grapes kiwi pears plantains pomegranates
vegetables:
Leafy greens such as Brussels sprouts, celery, cabbage, collard greens, kale and Swiss chard Green onions Onions Potatoes Pumpkins Root vegetables such as beets, carrots, parsnips, rutabaga and turnips Sweet potatoes/yams Winter squash
Want to give your kids the ultimate advantage? Sign up for CNBC’s new online course, “How to Raise Financially Smart Kids.” Learn how to build healthy financial habits now to set your kids up for greater success in the future. Use coupon code EARLYBIRD for 30% off. Offer valid from December 8th to December 22nd, 2025. Terms and conditions apply.
