Updated 19th March 2024

3 new studies: Blood fat, ultra-processed food, and dementia

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Welcome to the 12th ZOE Nutrition Research Roundup. This series translates the latest nutrition research into bite-sized, actionable chunks.

Today, we tackle blood fat and the links between ultra-processed food and dementia. We also ask whether exercise can reduce Alzheimer’s risk.

So, let’s get cracking.

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1. 10,000 steps and blood fat

When you eat, fat in your food enters your bloodstream. Once there, it moves around your body before being used or stored.

So, after a meal, there’s a relatively sharp increase in the level of fat in your blood. This is called postprandial lipidemia. 

Over the following hours, there’s a gradual decline as the fat leaves your blood.

This is all normal and healthy. But the process differs between people — some clear fat from their blood faster than others. 

If fat hangs around in your blood for longer periods, it can start to damage your health.

People with more pronounced blood fat responses have an increased risk of atherosclerosis and heart disease.

So, a recent study investigates whether walking could improve postprandial lipidemia.

What did they do?

Ten healthy participants took part in the study. On separate days, they walked different distances: 2,000, 5,000, 10,000, or 15,000 steps.

Then, they all tucked into a high-fat meal. Before the meal and five times afterward, the researchers took blood samples.

What did they find?

According to the analysis, postprandial lipidemia was significantly higher in people who walked just 2,000 steps than those who walked 10,000.

In other words, walking 10,000 steps reduced the blood fat response to a meal later in the day.

What should you do?

Keeping active is a vital part of a healthy lifestyle. And this study shows that even walking can improve how your body responds to a meal.

So, after reading this, why not go for a stroll? And while you’re out there, listen to this podcast, which busts some common exercise myths. 

2. Ultra-processed food and dementia

Ultra-processed foods (UPFs) are industrially prepared products with a laundry list of ingredients, most of which you wouldn’t find in a regular kitchen.

In many Western countries, a high percentage of our calories comes from these items every day.

Evidence is mounting that UPFs are bad for our heart health. And poor heart health is associated with dementia. So, could UPFs influence dementia risk?

A recent meta-analysis investigates.

What did they do?

The researchers pooled data from 10 studies, including 867,316 participants total, and it reanalyzed the results.

What did they find?

The researchers found that a high intake of UPFs was associated with a higher risk of dementia, compared with a low intake of these foods.

What should you do?

Whenever you can, try to reduce your intake of UPFs. It’s virtually impossible (and probably unnecessary) to cut them out entirely, but any reduction is good news.

We have a handy article on how to spot and avoid UPFs. And for more information about UPFs and brain health, try this podcast.

3. Exercise and Alzheimer’s

Globally, around 55 million people are living with dementia. And there are another 10 million new cases each year.

As the world’s population slowly ages, scientists are focusing on ways to reduce the risk. And some are looking at exercise.

It’s increasingly clear that a sedentary lifestyle increases your risk of developing dementia.

However, the evidence that exercise can protect against Alzheimer’s — the most common form of dementia — is less compelling.

So, a group of researchers recently designed a meta-analysis to investigate.

What did they do? 

They pooled results from 29 studies, including data from ​​2,068,519 people.

What did they find?

Overall, the authors concluded that moderate-intensity exercise is linked to a reduced risk of developing Alzheimer’s. 

And more vigorous activity was associated with an even greater reduction in risk.

What should you do?

We’ve already said it today, but it’s worth repeating: Keeping physically active is a vital component of a healthy lifestyle. So, get active when you can.

Listen to our recent podcast on cardio exercise if you need some inspiration and motivation.

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The take-home message

That’s a wrap. And today’s takeaways are simple:

  1. Start or keep being active: It might lower the level of fat in your blood after you eat and reduce your Alzheimer’s risk.

  2. Avoid UPFs when you can: Limiting these foods might reduce your dementia risk, among other health benefits.


Acute effects of daily step count on postprandial metabolism and resting fat oxidation: A randomized controlled trial. Journal of Applied Physiology. (2023). https://pubmed.ncbi.nlm.nih.gov/37560764/ 

Consumption of ultra-processed foods and health outcomes: A systematic review of epidemiological studies. Nutrition Journal. (2020). https://nutritionj.biomedcentral.com/articles/10.1186/s12937-020-00604-1 

Dementia. (2023). https://www.who.int/news-room/fact-sheets/detail/dementia/ 

Dementia prevention, intervention, and care: 2020 report of the Lancet Commission. Lancet. (2020). https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(20)30367-6/fulltext 

Effect of physical activity on risk of Alzheimer's disease: A systematic review and meta-analysis of twenty-nine prospective cohort studies. Ageing Research Reviews. (2023). https://www.sciencedirect.com/science/article/abs/pii/S1568163723002866 

Fasting compared with nonfasting triglycerides and risk of cardiovascular events in women. JAMA. (2007). https://pubmed.ncbi.nlm.nih.gov/17635891/ 

Heart disease as a risk factor for dementia. Clinical Epidemiology. (2013). https://www.tandfonline.com/doi/full/10.2147/CLEP.S30621 

High intake of ultra-processed food is associated with dementia in adults: A systematic review and meta-analysis of observational studies. Journal of Neurology. (2023). https://link.springer.com/article/10.1007/s00415-023-12033-1 

Mechanisms of atherosclerosis induced by postprandial lipemia. Frontiers in Cardiovascular Medicine. (2021). https://pubmed.ncbi.nlm.nih.gov/33996937/ 

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