What causes muscle loss as we age?

There are numerous, inter-connected factors that likely contribute to the loss of muscle mass and function with age, some key ones include:

Reduced physical activity

A major cause of sarcopenia is the simple fact that, as we age, we tend to do less physical activity. Even short periods (2-3 weeks) of reduced daily steps lead to declines in muscle mass in older adults [1]. These periods of reduced activity can occur relatively often (e.g. due to injury/a cold/minor illness, the beast from the East!) and are difficult for older adults to fully recover from [2].

Old man sitting

Poor nutrition

Compared to younger adults, older adults require more protein in their diets (found in foods like milk, yogurt, fish, eggs, meat, beans, nuts) and not eating enough protein can contribute to muscle loss. Other contributors include not eating enough food (for example due to poor appetite) and vitamin D deficiency [3].


Imbalance between muscle building and muscle breakdown

Our muscles are constantly undergoing cycles of building and breakdown. When rates of muscle building and muscle breakdown are equal, which is the case in younger adults, muscle mass remains stable. In older adults, however, rates of muscle building are blunted, especially in response to “muscle building triggers” like eating protein-rich foods or performing exercise [4]. This means that the balance between building and breakdown is tipped towards less building and more breakdown.


Changes to nerves and muscles

An important cause of strength loss is age-related changes to nerves and muscles. As we get older we begin to lose nerve cells that are responsible for carrying messages to our muscles to tell them to contract. There is also a decline the number and size of our muscle cells (called muscle fibres), especially the “fast” type of muscle fibres. The “fast” type of muscle fibres generate more force than the “slow” type of muscle fibres [5].

Hormone changes

As we age the levels of a variety hormones change in our bodies. In particular, the decline in the hormone testosterone that occurs with age, especially in males, is thought to contribute to muscle and strength loss [6]. This may explain why men tend to lose muscle faster than women as they age.


Older adults tend to have slightly increased levels of inflammatory chemical messengers in their blood. This state of chronic low-grade inflammation may play a role in age-related muscle loss [5].

Fat infiltration into muscle

Aging is associated an increase in fat accumulation inside our muscles. Fat infiltration has been linked to reduced muscle mass and quality, as well as reduced physical performance among older adults [7].


This image shows the inside of a thigh from a young man (left) and older man (right). The dark colour shows muscle and the light colour shows fat. The older man has less muscle in his thigh and more fat, both surrounding the muscle as well as inside the muscle [8].

Oxidative stress

Reactive oxygen species (ROS), otherwise known as free radicals, are naturally formed inside our body cells, including our muscle cells. These ROS play an important role in our bodies provided their levels are kept under control. In order to control the ROS levels, our cells have inbuilt anti-oxidant mechanisms that scavenge and quench the ROS. However, in older adults, there is increased production of ROS and the inbuilt anti-oxidant mechanisms are not as effective at dealing with the ROS. This can lead to excessive ROS levels and result in damage inside the muscle cells [9].



What does a screening visit for the NUTRIMAL Project involve?

The purpose of the screening visit is to assess whether the individual is eligible to take part in the NUTRIMAL Project. Information on who is eligible to take part in the study is shown on one of our previous posts.

To be eligible for the study the participant must have low muscle mass and/or low strength so this is the first thing we measure.

How we screen for low muscle strength 

We screen for low muscle strength by asking the participant to squeeze a device (called a handgrip dynamometer) as hard as possible! If a man squeezes less than 30 kg or a women squeezes less than 20 kg this means their strength is low.

How we screen for low muscle mass

We measure how much muscle the person has in their body using bioelectrical impedance analysis (BIA).

Screen Shot 2018-03-05 at 4.19.36 PM

How the BIA works

The participant stands on the BIA monitor in bare feet and holds on to a rail. A very low, safe (completely painless!!) electrical signal is sent through the body.

The electrical signal passes quickly through tissues that are high in water content (i.e. muscle) the signal but meets resistance when it hits fat tissue. This resistance is measured and is used to calculate how much muscle is in the body.


If the participant has low strength and/or muscle mass we go on to the next phase of the screening visit:

Medical history questionnaire 

We ask about the person’s medical history. This helps us to ensure that it is safe for the participant to take part. In addition, some medical conditions are associated with muscle wasting (i.e. COPD, cancer, liver failure). The muscle wasting with these conditions may not respond to the NUTRIMAL drinks in the same way as age-related muscle loss, and because of this participants with these conditions are not eligible for the study.

We also ask what medications the participant is on. There are certain medications that can affect muscle and may prevent us from seeing a beneficial effects of the drinks so unfortunately participants on these medications cannot take part (i.e. steroids, hormone replacements and suppressants, some cholesterol medications).

Usual diet

We ask the participant what they eat in a usual day. We are particularly interested in how much protein the participant usually eats at breakfast. Previous research has shown that  older adults need more protein than younger adults to maximize their rate of muscle building and should aim to consume ~30 g of protein at each meal.

However, dietary surveys show that older adults often consume less than this – especially at breakfast.

In the NUTRIMAL Project we are aiming to boost protein at breakfast using the supplemental drinks. However, if someone is already eating a sufficient amount of protein at breakfast then the drinks are unlikely to have a beneficial effect on muscle. Therefore people already eating high protein breakfasts are not eligible for the study.

Meal 5Porridge with fruitApple

Memory test

This helps us to ensure each participant has the cognitive capacity to fully understand the study procedures and to make an informed and rationale decision about whether or not they want to take part in the study.

The screening visit takes about 1 hour in total.

Our first participant completes the NUTRIMAL Project!

Our first participant has officially completed the NUTRIMAL Project! The lovely Teresa (83 y) first heard about the NUTRIMAL Project at the 50 plus expo in the RDS in 2016 and officially started the study in June 2017. We could not have asked for a more fantastic participant! Teresa always arrived to her visits in UCD with a smile on her face and stuck to her supplements rigorously throughout the 6 months. Despite the fact that it is us who should be thanking Teresa for generously giving her time and commitment to the project, Teresa arrived to her final study visit with a lovely card and chocolates for the NUTRIMAL team!


The NUTRIMAL team would like to say a huge thank you to Teresa and to all of the participants in the Nutrimal Project!

The NUTRIMAL project at the 50 plus expo

The NUTRIMAL project had a stand at the 50 plus expo which took place in the RDS in Dublin Oct 20th-22nd 2017. The 50 Plus Expo is the only national consumer event dedicated to older people in Ireland and hosts a number of information and education stands on everything from the winter flu vaccine to retirement planning to yoga. The event attracts thousands of people aged 50 and over every year making it an ideal place for us to recruit participants for the NUTRIMAL project.


At our stand we offered free strength testing and told people about our study. Our stand got lots of interest with queues even forming for the strength testing and over 90 people signed up to attend a screening visit for the NUTRIMAL project. I was lucky to have lots of help at the stand from the great students working on the project!


My sister’s boyfriend who is doing a masters in interactive design helped me design the posters for our stand – compared to my first draft they looked far more professional after he edited them!


We also attended the event in 2016 and it was there that we recruited a number of participants who are currently in the NUTRIMAL project! It was great to bump into them again this year at the expo!

In the afternoon I gave a talk on “Healthy Eating for Positive Aging”. Initially when I turned up to give my talk this was my audience…


Fortunately however it turned out I had just been told the wrong time and luckily an audience showed up an hour later 🙂

Some key points from my talk on Healthy Eating in the over 65s were:

  • A good diet and physical activity are powerful strategies to help you keep your body healthy as you age


  • The new fruit and veg recommendation is 5 – 7 portions per day

1 portion = 1 medium fruit like an apple or banana, 2 small fruits like kiwis or mandarins, 1 cup of cooked veg, 1 bowl of homemade soup or salad


  • Fibre helps to prevent constipation and reduce the risk of colon cancer. Choose whole grains  (i.e. brown bread, wholegrain cereals, brown rice, brown pasta, quinoa, wholegrain cous cous) rather than white versions and keep the skins on potatoes and fruit to get more fibre in your diet. When increasing your fibre make sure to also drink plenty of fluid (aim for 8 glasses of fluid per day i.e. water, tea, coffee etc.) or constipation may get worse.


  • We lose muscle mass and strength we age. Protein (found in foods like eggs, milk, yogurt, fish, meat, beans, tofu and nuts) is critical for your muscle. Older adults need more protein than younger ones, try to have it at every meal of the day. Older adults typically don’t eat enough protein at breakfast in particular!


  • Physical activity is one of the most important things you can do for your body. If it was a medication every doctor would prescribe it – keep active!Slide3

Why healthy aging research is now more important than ever

The Irish population is aging. This is also the case in virtually every other country in the world. At the moment in Ireland there are 540,000 people aged 65+ (accounting for 12% of the Irish population). By 2041 this number will increase to 1.4 million (22% of the Irish population[1].


Life expectancy has also increased dramatically over the past 100 years [2]. For example, the average female born in Ireland today can expect to give 29 years longer than the average female born in 1911!

slide2This increase in life expectancy is a great achievement, but as we all know getting older is associated with increased risk of physical disability and other health problems. Therefore, it is now more important than ever that we find ways to preserve health and quality of life during these gained years of life expectancy.

Therefore the aim of healthy aging studies, like the NUTRIMAL project, is to find ways to help keep older adults well, independent and happy as they get older.

Recruitment begins on Newstalk with Pat Kenny!

Recruitment for the NUTRIMAL project officially kicked off in August 2016 on the Pat Kenny radio show!

Pat Kenny

Prof Helen Roche went live on Ask the Expert on Newstalk and discussed nutrition, supplements and exercise with Pat. Helen answered questions texted in by listeners which included a wide range of topics such protein supplements, which oil to use in cooking and whether or not to chocolate milk is a healthy option.

Helen also told Pat about the NUTRIMAL project and invited interested listeners to contact us to find out more about participating in the research study.

Here’s a link to the show if you’d like to have a listen:


After the show we got lots of calls of from members of the public who were interested in participating, some of whom are now NUTRIMAL participants!


I’m Caoileann Murphy, the postdoctoral researcher running the NUTRIMAL project. The NUTRIMAL project is co-ordinated by Prof. Helen Roche at UCD and Dr Brendan Egan in DCU. Also collaborating on the project are Professor Giuseppe De Vito and Dr Clare Corish from UCD, Dr Sinead McCarthy from Teagasc, Glanbia and Smartfish.


Prof. Helen Roche is a Dietitian head of the the Nutrigenomics Research Group in UCD.  Nutrigenomics is the study of the interaction between our genes, what we eat and our health. For example how does what we eat affect which of our genes are ‘switched on’? And how do our genes affect our ability to get health benefits from a certain diet?


Dr Brendan Egan is a Sports Scientist/Nutritionist and is a Senior Lecturer in Sport and Exercise Physiology in Dublin City University. His research group is particularly interested in muscle and investigates how nutrition and exercise work together to optimise performance in athletes and older adults. Dr Egan also consults as a performance nutritionist to elite team sport athletes.



Professor Giuseppe De Vito is the Head of the School Public Health, Physiotherapy and Sports Science at UCD. Professor De Vito’s research mainly focuses on muscle function in older and younger adults. Professor De Vito is a trained Medical Doctor and takes the muscle samples from the NUTRIMAL project participants who chose to take part in this optional, additional measurement.


Dr Giuseppe De Vito

Dr Clare Corish is a Dietitian and Associate Professor in Nutrition and Dietetics in UCD. Dr Corish recently set up the first ever MSc programme in Nutrition and Dietetics in the Republic of Ireland in UCD. Dr Corish is also very involved in research, in particular in relation to malnutrition in older adults.

Clare Corish

Dr Clare Corish

Dr Sinead McCarthy is a Research Officer at Teagasc. Dr. McCarthy has a background in Public Health Nutrition and her research focuses on consumer behaviour in relation to food and health.

Dr Sinead McCarthy

And of course you know me from the homepage! I trained as a Dietitian in Dublin and did my PhD in Canada investigating how we can use nutrition and exercise to slow the loss of muscle and strength in older adults. I started my job as a postdoctoral researcher in UCD in 2016 working on the NUTRIMAL project and I am really enjoying it so far!


Where does the funding for the NUTRIMAL project come from?

NUTRIMAL is funded by the Department of Agriculture Food and Marine (DAFM) under the Food Institutional Research Measure. In 2014, Professor Helen Roche and Dr. Brendan Egan, in collaboration with a number of other researchers, applied for a highly competitive grant offered by DAFM. The (50 page!) NUTRIMAL project grant proposal was scrutinized by an Expert Evaluation Panel made up of experts in research, the agri-food industry and the public service and was selected to receive the funding.

After I joined the team we successfully applied for additional funding to add some extra measurements to the project. This involved a few more applications and an interview! The NUTRIMAL project has received funding from European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 666010 and the European Society of Clinical Nutrition and Metabolism (ESPEN) under the 2017 ESPEN Fellowship programme.

The ingredients for the NUTRIMAL project drinks have been kindly donated by Smartfish and Glanbia Nutritionals. Here is in UCD we spotted that both of these companies were producing ingredients with the potential to improve muscle health in older adults and brought them together to produce a custom-made product for the NUTRIMAL project that is not commercially available.


What are the NUTRIMAL nutritional supplements?

The supplements are fruit flavoured drinks approximately the size of a small apple juice carton (200 ml).

They are produced by a Norwegian company called Smartfish and incorporate a food ingredient produced by the Irish company Glanbia.Nutritionals. I think they taste great!

Me tasting NUTRIMAL drinks


The drinks are not commercially available and were custom-made for the NUTRIMAL project. Each participant will be randomly allocated to receive one of the following supplements for the 6 month period:

Supplement 1

Supplement 1 contains milk protein (whey).  Evidence from previous research studies suggests that whey protein from milk is especially effective for increasing the rate of muscle building in older adults. In addition, this supplement has added leucine. Leucine is one of building blocks that makes up protein in foods and is known to have a special role as a ‘trigger’ for muscle building.

There is also some carbohydrate (from fruit sugars) and fat (from sunflower oil) in this supplement.

There are 200 calories per drink.


Supplement 2

Supplement 2 contains milk protein with added leucine (just like supplement 1) but it also contains omega 3 fatty acids from fish oil. A previous study found that older adults supplemented with fish oil for 6 months had an increase in muscle mass and strength. However, no studies have examined if a combination of whey protein, added leucine and fish oil can lead to an even greater improvement in muscle mass and strength than whey protein and added leucine alone…and that is what we want to find out in the NUTRIMAL study.

There is also some carbohydrate (from fruit sugars) in this supplement.

There are 200 calories per drink.


Supplement 3

Supplement 3 placebo (contains no milk protein or fish oil). This supplement contains fat (from sunflower oil) and carbohydrate from fruit sugars as well as added sugars (~ 3 tsp added sugar per drink).

There are 200 calories per drink.


Who are the participants who will take part in the NUTRIMAL project?

We are currently looking for men and women to take part who are:

  • 65 years of age and over
  • Non-smokers
  • Have low muscle mass and/or have low strength (we will test this)

Older adults group

Unfortunately men and women are not eligible if they:

  • Regularly perform strenuous weightlifting exercise (why?)
  • Have diabetes (why?)
  • Have advanced kidney disease (why?)
  • Have a gut disease that impair their ability to properly absorb their food (why?)
  • Are on certain medications (i.e. high dose anti-inflammatories, hormone replacements or hormone suppressants) (why?)
  • Have had substantial (>3 kg) weight loss in the past 3 months (why?)
  • Have normal muscle mass and strength (why?)