With a rapidly ageing population worldwide, more adults than ever are becoming at risk of nutritional frailty. Older age is a time when specific nutrient needs may be higher while the ability to meet those needs has more barriers. In this podcast, I’ll highlight how our nutrition needs change as we age, the factors that make it harder to meet these needs, and the role that nutrition can play in promoting healthy ageing and improving the outlook of age-related diseases.
The world and its population are ageing. We’re living longer and because of that, comes a slew of potential problems related to our health. In Australia alone, older people make up a considerable proportion of the population with over 1 in 7 people aged 65 and over. Compare that to almost 100 hundred years ago when just 5 people in one hundred made it past 65 years. And future projections put the number of older adults in Australia at more than 1 in 5 in just the next 30 years. You’ll find similar trends in just about all countries and globally, the number of older persons is expected to double by 2050.
And with age comes a variety of changes to the body, including muscle loss, thinner skin and less stomach acid. And so too are their changes in our nutritional needs. Protein especially is one of the few nutrients where you see a substantial jump in official recommended intakes once someone hits their senior years and for good reason – more about that shortly.
But having official recommendations for nutrient goals is one thing, achieving them is another. And this is where the more unique factors related to ageing comes up that can compromise meeting nutrient needs and exacerbating the risk of deficiencies.
First, there are social factors such as a change in housing and living situation, having the kids moving out and perhaps living a long way away and the change in family dynamics that come with that. And then there can be the loss of a partner and all the upheaval that can cause. And of course, changes in income going from employment to retirement can all also affect someone’s living circumstances. Depression, lack of independence, and social isolation are also big factors that can make food less appealing, further contributing to a less than ideal intake.
Then there are physiological factors such as a decline in health and the presence of chronic disease. For instance, atrophic gastritis which is common in adults over 50 results in stomach inflammation and a decline in factors needed for vitamin B12 absorption. Mobility issues can affect access to food and even the ability to open jars and containers or lift heavier things in the kitchen. Poor dentition, swallowing problems and changes in taste and smell all affect the eating experience.
The result of all of this is a greater risk and presence of malnutrition in seniors. Estimates point to 1 in 3 community-living older people being malnourished. That number escalates when you look at hospital and institutional settings.
And the consequences of all this? A compromised immune system, muscle weakness and decreased bone mass which can lead to falls and fractures, poor wound health, and a higher risk of hospitalisation and earlier mortality.
Dietitians know to always be on the lookout for potential malnutrition in older people with screening and assessment tools that look at recent unintentional weight loss, eating problems, a change in how much food is eaten and how active they are.
Nutrients
There are some nutrients that are more of a concern than others as being inadequately consumed in older adults and these include protein, omega-3 fatty acids, fibre, calcium, magnesium, potassium, and the vitamins A, B6, B12, D and E.
Let’s take vitamin D as an example. Vitamin D is found in only a few foods, so the sun is the major source. Less mobile people such as those in nursing homes are at greater risk of deficiency and this is compounded by a decline in kidney function with age as the kidneys are needed for vitamin D activation.
Low levels of vitamin D are associated with lower-extremity muscle weakness, impaired balance and accelerated loss of muscle mass, strength and physical function. That makes vitamin D deficiency an independent predictor of falls in older people.
A recent meta-analysis of 47 RCTs designed to reduce falls and fracture risk with vitamin D supplementation concluded that vitamin D supplementation can play an important role in reducing the risk of falls. A benefit of vitamin D on fracture risk reduction though was only seen with vitamin D and calcium supplements combined. And a greater benefit with vitamin D was seen at doses above >800 IU/d. And I’ll link to this review in the show notes. https://pubmed.ncbi.nlm.nih.gov/32846760
Bodyweight
Excess body weight gets a big focus throughout the lifespan for its link with chronic disease. But once a person gets into older age, that link starts to unravel. Just looking at BMI at a population level in adults over 65 years of age and its link to earlier mortality, there is a clear U shape to the graph which isn’t so surprising as very low and very high body weight are linked to earlier mortality.
What is surprising is that the bottom of that U curve comes in at around a BMI of 28. This gives credence to current recommendations on body weight in older age that a ‘healthy’ BMI range should be raised to 23 to 31 rather than the normally used range of 20 to 25. In older age, a higher BMI can be a sign of better nutrition and hence less risk of malnutrition. And that extra fat mass can give some real-world padding to the body to help protect it against falls. What this means is that less of a focus should be given to excess body weight as someone gets older.
Sarcopenia
Perhaps the key concepts that arise when looking at health in older age is that of nutrition frailty and sarcopenia. Nutrition frailty is a state commonly seen in older adults characterised by significant loss of weight, muscle mass and strength making the person susceptible to disability. This is all impacted by chronic undernutrition, the presence of disease, hormonal changes and decreased physical activity. Which then leads to sarcopenia.
Sarcopenia is a syndrome characterised by progressive and generalised loss of skeletal muscle mass and strength and it is strictly correlated with physical disability, poor quality of life and death. Ageing is a major cause of sarcopenia. After the age of 30, we can lose as much as 5 percent of our muscle mass per decade. Sarcopenia is compounded by a decline in physical activity, a decrease in motor neuron recruitment, and a further decline in anabolic hormones. With all of this underpinned by chronic inflammation. This is the absolute key reason why both resistance exercise and a high protein diet are the cornerstones of management and prevention of sarcopenia.
Protein recommendations of up to 1.5 g/kg body weight in older age are the norm now when overt sarcopenia is present which when combined with some form of resistance exercise can help to preserve and build back valuable muscle mass.
When you combine the presence of chronic disease and sarcopenia in older age, you soon come across an underlying descriptor of it all and that’s a term called inflammaging. Ageing is characterised by chronic low-grade inflammation. And that’s important because most chronic diseases have inflammation underlying them.
Chronic inflammation increases platelet activation and blood clotting. It can also deplete the reserve of internal antioxidants, generate free radicals and amplify oxidative stress. And it will even delay wound healing and tissue regeneration and promote cell ageing and premature cell death. I’ve already done a whole podcast on the topic of inflammation back in episode 61 so check that out for a which wider view.
Because inflammation applies to ageing, or inflammaging, there is now growing evidence linking a dietary pattern ranking high in its proinflammatory potential (and here, think a typical western diet high in highly processed foods and low in fibre) and a greater risk of the presence of inflammation, low muscle mass, low muscle function and sarcopenia. And I’ll link to some of this research which was done on older Australians in the show notes and which found that a high dietary inflammatory index score was directly associated with lower lean body mass and less mobility as assessed by a timed up-and-go test where a person from a sitting position has to stand up, walk 3 metres, turn around and walk back again. The longer it takes, the more it says about your mobility, strength and balance. https://www.mdpi.com/2072-6643/13/4/1166
Diet and lifestyle choices can go a long way to treating inflammation. And for diet, what is widely considered an ‘anti-inflammatory diet’ is one high in fruits, vegetables, healthy fats, legumes, and whole grains. A Mediterranean-style diet would be one such variation of this especially when you add in fish and olive oil.
But it doesn’t stop there. Exercise is also a potent force against chronic inflammation with a negative association between physical activity levels and CRP which is a blood marker for inflammation. So exercise in older age not only helps fight sarcopenia but helps address inflammation – it’s all related.
And then we have dietary fibre which is inversely associated with CRP levels. Fibre is primo fuel for our gut microbiome which is a big player in chronic inflammation, especially when you consider our gut is the home to most of our immune activity.
When certain beneficial bacteria ferment fibre, they produce butyric acid. Butyric acid helps mediate the immune response, lower circulating inflammatory markers and improve the integrity of the gut barrier. Beneficial microbes also help fight off more inflammatory, gut-damaging microbes directly by suppressing their growth.
Cognitive decline
Of all the diseases linked with ageing, it would be those of cognitive decline such as Alzheimer’s disease that are the most devastating for the person and their family. There is no single cause of dementia, but one factor that is considered a culprit is oxidative stress and inflammation – yet again. There has been interest on if antioxidants and other nutritional supplements can play a role in curbing the damage seen in cognitive decline.
Antioxidants came to the public’s attention in the 1990s when scientists began to understand that free radical damage was involved in the early stages of heart disease, cancer, vision loss, and a host of other chronic conditions. Some studies showed that people with low intakes of antioxidant-rich fruits and vegetables were at greater risk for developing these chronic conditions than were people who ate plenty of those foods.
There is though very mixed and inconsistent evidence that nutritional supplements such as vitamin B6, B12, C, or E; folate; or omega–3 polyunsaturated fats play a protective role when given in isolation. Yet observational evidence points to a diet containing foods high in phytonutrients offering some degree of protection. And the disconnect here is that antioxidants are not just one molecule, they represent a property that is part of many vitamins and minerals. And there are thousands of other chemicals that have some potential antioxidant activity and these compounds are called polyphenols. There are over 8,000 different types of polyphenols found in fruits, vegetables, grains, legumes, tea and coffee.
A brief reading about polyphenols on the Internet will bring up article after article highlighting that polyphenols are antioxidants and that explains their health benefits. Nutrition science though has well-and-truly moved on from using such simplistic language and concepts to describe how these thousands of polyphenols found in food work. They are much more than antioxidants. Focusing only on antioxidants or a single phytonutrient is like zeroing in on a section of a painting and seeing only the dots. You need to step back and see the bigger picture. It should instead be about polyphenols and their multitude of benefits and actions in the body such as:
Regulating cell growth and deathSlowing down cancer cell proliferationAltering glucose responses and insulin sensitivityIncreasing activity of enzymes involved in removing harmful substances from the bodyDecreasing inflammation
Taken together, it strongly advocates for a food-first approach if nutrition is to have a role in halting cognitive decline, rather than taking nutrient supplements in isolation.
This leads me in to just what are the characteristics of a diet that could be linked to reducing the risk of dementia. And here we have has been termed the MIND diet which has been developed over many years out of research. And by diet here, I mean ‘way of eating’ not ‘weight loss’. MIND here is an acronym for Mediterranean-DASH diet Intervention for Neurodegenerative Delay. It combines characteristics of a Mediterranean-style diet with the DASH diet where DASH stands for Dietary Approaches to Stop Hypertension. The DASH diet can lower high blood pressure which is a risk factor for Alzheimer’s disease. And on top of this, the MIND diet also includes foods specifically relevant to brain health.
Here is what a MIND diet could look like:
The diet also limits how much red meat and highly processed discretionary foods like sweets and fast food.
We probably won’t see any time soon a long-term RCT testing the effectiveness of the MIND diet in reducing the risk of dementia considering the time frames involved, but there has been some recent observational research that does support a link. For example, an Australian study of 1,220 adults aged 60 years and over without dementia who were followed for 12 years found a 19 percent reduced odds of developing mild cognitive impairment or dementia for those people adhering closely to what a MIND diet and this benefit was much greater than those just following the principles of Mediterranean diet alone. And I’ll link to this study in the show notes. https://pubmed.ncbi.nlm.nih.gov/30826160
And final mention today goes to our gut microbiota which, as you can probably guess, changes with older age, especially over the age of 80 where diet, lifestyle and other factors have the biggest impact on the health of the person. The ageing microbiota, like the ageing person, suffers from reduced resilience. And there is some research to show that there could also be a healthy microbiome fingerprint linked to improved health and longevity, though this is certainly a very nascent area.
Summary
So, let’s wrap this up. Nutrition becomes even more important in older age when you consider how many barriers can arise to eating well. Some aspects of ageing may be inevitable, but the risk of specific age-related disease and disability may, in part, be mediated by dietary intervention.
And one of the most important ways to do this is from regular resistance activity and meeting a higher goal for protein which can help fight against age-related loss of muscle mass. Further, increasing evidence suggests that a variant around the theme of a Mediterranean-style diet that is high in fruit (especially berries), nuts, legumes, fish, and vegetables may reduce the risk of both mild cognitive impairment and AD along with improving gut microbiota health. The themes of this style of eating can be adapted to any person’s dietary preferences or cultural background and is not a way of eating that should be changed to in older age, but instead to consider adopting earlier in life.
So that’s it for today’s show. You can find the show notes either in the app you’re listening to this podcast on if it supports it, or else head over to my webpage www.thinkingnutrition.com.au and click on the podcast section to find this episode to read the show notes.
If you find this podcast of value, then please consider sharing it with your friends and colleagues. Or maybe even leave a review. This all helps increase the ranking and reach of the podcast which means a big win for credible evidence-based nutrition messages while helping to dilute out the crazy and making the world a slightly less confusing place.
I’m Tim Crowe and you’ve been listening to Thinking Nutrition.