Your top 10 burning questions, answered by Tim Spector

Imagine you had one of the world's top health scientists on speed dial. What would you ask to help improve your health? 

When we recently asked our community this question, you sent in hundreds of queries. And Tim Spector answered your call.

He’s ZOE's scientific co-founder and a professor of epidemiology at King's College London — and his scientific career has led him in many fascinating directions.

Tim has researched everything from back pain to anxiety, from snoring to sexuality. More recently, he’s zeroed in on nutrition and the trillions of bacteria that live in your gut.

So, what did you ask, and what actionable advice did Tim offer?  

1. Should I use alternatives to sugar, like honey? 

Not necessarily. Alternatives to sugar aren’t magically better for you.

Honey and (possibly) maple syrup are the only potential exceptions, as they contain some polyphenols.

But the sugar in honey, syrups, nectars, starches, and the dozens of other alternatives still contribute to the freely available sugars in your diet that cause quick blood glucose spikes. 

If you want to satisfy your sweet tooth, try adding vanilla or cinnamon and whole fruits.

2. What’s your opinion of salt in food?

Salt is not the problem.

Adding salt to whole foods — especially potassium-rich vegetables —  during cooking is not an issue, and neither is the salt used in fermenting.

The issue is the added salt in snack foods, breakfast cereals, and other ultra-processed foods.

We know that potassium works well with sodium to reduce the impact of added salt.

In food terms, this means that eating vegetables that are naturally high in potassium will mitigate any negative effects of too much sodium. It helps explain why fermented sauerkraut (made with salt) is still good for our health.

3. Is eating fruit bad for my blood sugar?

Eating whole fruits is good for your health. If you have a poor blood glucose response, it’s better to eat fruit at the end of a meal or with some nuts and yogurt. 

Whole, colorful fruits, like berries and plums, have extra polyphenols that are great for your gut microbes.

We think that our gut bacteria use these polyphenols as prebiotic fibers to make helpful chemicals for us. They act like rocket fuel for our microbes.

4. Should we avoid seed oils?

No, there’s no need to avoid seed oils. Some people claim that they’re linked to inflammation, heart disease, and weight gain. But there’s no evidence that this is true.

I prefer to use extra virgin olive oil when possible because it contains polyphenols and monounsaturated fats, which can help lower your levels of “bad” cholesterol. 

5. What serving sizes count toward my 30 plants a week?

There are no exact serving sizes, but a handful of fruits, vegetables, whole grains, and beans — and a teaspoon of nuts, spices, seeds, and herbs — is a good starting guide. 

Research shows that people who eat 30 different plants each week have more of some “good” gut bacteria than people who just eat 10.

This is because plants contain polyphenols and prebiotics, which feed your gut microbiome.

And because every plant is different, a variety of plant foods help feed a variety of gut bacteria. This keeps your gut microbiome diverse and well-fed. 

6. Is eating meat bad for our health?

No, not necessarily. We should all be more plant-focused, but many animal foods, like eggs and kefir, are highly nutritious and can form a part of a healthy, sustainable diet. 

Just remember to treat animal-based foods as a rare treat to be savored. 

I rarely eat meat, and I eat fish once or twice a week. When I do, it’s a real treat, so I choose the best quality I can and really make the most of it.

7. What single change to our diets would you suggest?

Eat more plants in their whole form, whether they’re fresh, frozen, fermented, dried, canned, or jarred. 

Despite what you might have heard, frozen fruits and vegetables contain just as many nutrients as fresh produce, and sometimes more.

On your next shop, pick up some mixed frozen vegetables, mixed nuts or seeds, and a can of mixed beans.

If you’re going out for a meal, pick the plants first, and see how that changes the way you think about food.

8. Are probiotic supplements worth it?

It depends. The science is evolving rapidly, and some supplements can be worthwhile. For example, Saccharomyces boulardii is a probiotic yeast strain used to treat diarrhea. It’s very effective.

However, I opt for a daily dose of fermented foods as my natural probiotics. Research shows that 3 small portions a day is a good starting point for change.

Fermented foods contain fiber, probiotic strains, and the chemicals created by the fermentation process, all in one tasty package. 

9. Would you like ZOE to be prescribed on the NHS?

Yes, it would be great to make it available to more people in this way.

Poor diet is a risk factor for the majority of chronic lifestyle diseases that are now common, like cardiovascular disease, type 2 diabetes, and even some cancers. 

And currently, the NHS focuses more on treating than preventing disease. 

Following a healthy diet that’s tailored to you can help hugely reduce your risk of a lot of these ailments, sometimes even reversing them and improving your quality of life.

So, we hope to work with the NHS in the future to make ZOE available to millions.

10. Where would you like to see ZOE in 10 years?

I want ZOE to change the way we all think about what we eat, to empower people to make informed decisions that improve their health.

We continually update our science — thanks to our members and cutting-edge technology — so our ability to tailor our advice will only get better and better. 

We have big dreams to reach as many people as possible, not only with our product, but also with our freely available science podcast, press, and writing. 


American Gut: An open platform for citizen science microbiome research. mSystems. (2018). 

Gut-microbiota-targeted diets modulate human immune status. Cell. (2021). 

Ultra-processed diets cause excess calorie intake and weight gain: An inpatient randomized controlled trial of ad libitum food intake. Cell Metabolism. (2019). ​​