I was a private chef on superyachts for 17 years. Billionaires want 5 things now that they're more health-conscious.

• Chris Demaillet, 43, was a private chef to the ultra-wealthy on superyachts for 17 years.
• He said his clients became more health-conscious over the years.
• Food upgrades his clients requested included using olive oil.

This as-told-to essay is based on a conversation with Chris Demaillet, 43, who is based in Mallorca, Spain. Business Insider has verified his former employment. This piece has been edited for length and clarity.

Fifteen years ago, if a private chef had asked me what training would be most valuable, I would have told them to go to Tokyo and learn to make sushi.

Nowadays, as the founder of Montclair Chef, an agency that places Michelin-level chefs with ultrawealthy families, I'd tell them to learn about nutrition, calories, and longevity protocols instead.

It's no longer just Californian clients asking for these things. Now, I'd say around 80% of the clients are prioritizing healthy eating, and a growing number are focused on longevity, whether that's by tracking macros, counting calories, or following a Mediterranean diet. It's also becoming more common for chefs to work alongside nutritionists and personal trainers to help families meet their goals.

Here are five food upgrades I've seen ultrawealthy families prioritize to live longer and healthier lives.

1. Use high-quality olive oil

As a private chef, olive oil was always my first choice for cooking and dressings. It's a big part of the Mediterranean diet, which many clients now ask us to follow for longevity reasons. Excellent extra-virgin olive oil is more expensive than sunflower oil or other cooking oils, but I think it's worth it.

2. Choose wild, line-caught fish

We always try to source wild, line-caught fish, such as sea bass. It isn't always possible, depending on where you are, and sometimes it's very expensive, but it's something I consider very important.

We also pay attention to how often we serve certain fish, such as tuna, especially when cooking for children, because you need to be mindful of mercury levels

3. Choose grass-fed and free-range meat

When I buy meat, including when shopping for my own family, I always look at where it came from and how it was raised. You want to go for grass-fed beef and free-range poultry.

It's a small step in the right direction.

4. Buy organic fruit and vegetables that are in season

Organic vegetables and fruit, always. Keeping it seasonal is always better, too. It's often cheaper and riper because it doesn't have to travel halfway across the world.

5. Avoid plastic

For some families, it isn't only about the ingredients. They ask their chefs to avoid plastic containers and plastic wrap where possible to reduce potential BPA exposure.

I learned all this in my 17 years as a private chef on superyachts

I grew up in a small village in France's Loire Valley and started training as a chef when I was 14. In 2006, in my early 20s, I worked at Michel Roux's three-Michelin-star restaurant, The Waterside Inn, in the UK, where I learned to make everything from scratch using the best ingredients.

After a year and a half, I traded restaurant kitchens for superyachts, where I spent the next 17 years working for ultrawealthy families, including the cofounder of Zara, Amancio Ortega.

When catering to the ultrawealthy, you have to be extremely consistent and ready for anything. The amount of stock and provisions you have to keep on a yacht is incredible because you need to be able to cook whatever your clients ask for, no matter where you are in the world.

But you don't need a private chef to live a healthier, longer life. Paying closer attention to the food you buy is a good place to start.

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