When it comes to healthy ageing, the overall quality of a person’s diet matters more than eating any one “superfood” or nutrient. From the Mediterranean diet to the Nordic diet, specific eating patterns have been shown to reduce the risk of heart disease, physical frailty and cognitive decline.
Authors
- Rachel Ann Da Costa
PhD Candidate, Aging Research Centre, Karolinska Institutet
- Adrián Carballo Casla
Postdoctoral Researcher in Geriatric Epidemiology, Karolinska Institutet
But while we know diet affects our health, we haven’t really been clear until now on the changes it causes inside the body which lead to these benefits.
This is exactly what our latest study set out to explore. We found that older adults who ate high-quality diets exhibited biological signs of healthier ageing that could be detected in their blood. These findings offer a clearer picture of the connection between healthy eating and healthy ageing.
We looked at data from 1,769 adults aged 60 and older living in Stockholm, Sweden. Participants completed detailed questionnaires about what they typically ate over the previous year.
Rather than focusing on single nutrients, diet quality was measured using three well-established eating patterns.
The first eating pattern was based on Mediterranean-style eating , which involves consuming foods typical of Mediterranean countries – such as plant foods, wholegrains and fish. The second eating pattern was based on guidelines for reducing chronic disease risk , which also place an emphasis on fruits, vegetables, nuts, legumes and avoiding processed and red meats, sugary drinks and trans fats (such as fried foods).
The third eating pattern considered how inflammatory a person’s overall diet was . Diet can play an important role in the development of chronic diseases through inflammation. Diets high in processed foods, red meats and sugary drinks have been linked to greater inflammation .
Participants received a score for how closely they adhered to each eating pattern. Those who regularly ate foods such as fruits, vegetables, wholegrains, legumes, nuts and fish received higher scores. Those who consumed less favourable components, such as refined grains, sugar-sweetened drinks and red and processed meats, received a lower score.
We then looked at how closely following each pattern related to 54 blood biomarkers related to ageing. Biomarkers are measurable signals of the biological processes unfolding in our bodies every day. The biomarkers we analysed covered metabolism, inflammation, vascular health and brain health. Other factors that could affect the results, such as age, sex, socioeconomic status, physical activity levels and smoking were also accounted for.
Our overall finding was consistent: people following healthier eating patterns had more favourable blood biomarker profiles. Two biomarkers stood out, both linked with all three measures of diet quality.
The first was folate, a B vitamin the body cannot make so it must be obtained from food or supplements. The body needs folate to support basic functions , including the formation of healthy red blood cells, production of DNA (genetic material) and cell renewal.
People following healthier diets had higher folate levels in their blood. This makes sense, given the healthy eating patterns we looked at generally include foods which are good sources of folate – such as leafy dark green vegetables, fruits and legumes.
Maintaining adequate folate levels may be particularly relevant in later life because the body’s ability to absorb and use certain nutrients can change with age . Low folate levels have also been linked to cognitive decline , making sufficient intake through diet especially important with increasing age.
The second biomarker was growth differentiation factor-15 – a protein that stressed or damaged cells release due to tissue injury, inflammation or cell death . Its levels tend to rise with age and with chronic health conditions .
Growth differentiation factor-15 reflects how much internal stress the body is under. Its consistently lower levels in participants who followed healthier diets suggests eating well helps reduce that underlying burden – regardless of the diet’s exact composition.
Of these three diet quality measures, the one that measured how inflammatory a person’s diet was was linked to the widest range of favourable blood biomarkers – six in total. These biomarkers were connected to several aspects of health, including blood sugar regulation, appetite and liver, bone and immune function.
The range of biological functions represented by these biomarkers suggests inflammation may be one important pathway connecting diet with the ageing process . Following diets with lower inflammatory potential (such as the Mediterranean-style diet ) may therefore help support several of the biological systems, many of which play a direct role in how the body ages.
This fits well with our previous research which found that people following a less inflammatory diet tended to accumulate chronic diseases more slowly.
Diet quality
There were a few caveats with our research. Because diet and blood markers were measured at the same point in time, it’s not possible to establish cause and effect. Diet was self-reported, which can introduce a level of uncertainty. Participants were also relatively healthy and well-educated, and lived in one urban area of Sweden. These characteristics may limit how broadly the findings can be applied to all populations.
Still, our findings add to a broad body of evidence linking healthy eating to lower risk of chronic disease, better physical and cognitive function and improved mental wellbeing in older adults. Our research also offers a biological explanation for how, by pointing to the measurable processes happening inside the body that may actually be responsible.
No single food or rigid diet stands out. What matters is the overall quality of the diet, maintained consistently over time. It’s that quality, our study suggests, which may tell part of the story of how well the body ages.
