In this blog post, I want to dive a little bit into nutrition, and more specifically about proteins. But before we go there let’s zoom out and get familiar with a few terms and concepts.
You may have heard the term ‘macro’ at some point or another. It is brought up a lot, especially when the topic is about eating healthily or losing weight.
Macronutrients are substances that are essential for the body to function properly and include proteins, carbohydrates, and fats. Proteins are used to build and maintain the body's tissues and organs, while carbohydrates provide a source of energy. Fats provide essential nutrients, energy, and essential fatty acids. All of these macronutrients are essential for a person to remain healthy.
I think most people know roughly what these are. What you may not know is that per gram of these macronutrients, they actually give different amounts of calories. For example, we typically measure energy in kilocalories or kcal, and if we look specifically at these 3 macronutrients, you will see that fat has roughly double the amount of energy per grams found in the other two macros (i.e. carbohydrates and proteins).
• Carbohydrates contain 4 kcal per gram
• Proteins contain 4 kcal per gram
• Fats contain 9 kcal per gram.
Let’s get back on topic and talk more specifically about proteins now.
Protein is a macronutrient that is essential for building muscle mass. Protein is composed of amino acids. Amino acids are the building blocks of protein.
Protein-rich foods include meat, poultry, salmon, tuna, egg, milk, cheese, or other types of animal by-product foods. These protein sources contain all of your essential amino acids. You can get the proper amino acids from eating a variety of plant protein sources such as beans, lentils, nuts, seeds, and soy as well as lower amounts in grains, vegetables, and fruits.
Now I think what most people don’t realise is that they vastly underestimate how much protein we need to eat and that most people are probably undereating the amount of protein they require.
Why is thinking about proteins important in the context of longevity, you may ask?
Well, the question really has to do with muscles. I like to think about muscles as serving 2 functions.
1 – Mobility — Functional mobility is critical. Most people reach the age of 65; however, after that point, many succumb to immobility-related causes such as falls, accidents, or hospitalization. Other causes of death include heart disease, cancer, and stroke which often co-exist with periods of immobility.
2 – Metabolism — Muscle is a primary site for insulin activity in terms of glucose utilization and fat utilization. Blood glucose and blood lipids are heavily dependent on muscle metabolism, and this obviously means that the amount you eat makes a difference. But the actual level is heavily dependent on your muscle metabolism.
How much proteins do we need?
So first, let’s talk about how much proteins we need. When most people talk about this, we usually refer to RDA or recommended daily allowance.
RDA for protein is calculated by multiplying an individual’s body weight in kilograms by 0.8. This provides the recommended amount of protein per day in grams. For example, an individual who weighs 70 kg would have an RDA for protein of 56 g/day.
So that’s it right? We just follow the recommended daily allowance. Well, I am here to tell you that you have to dig a little deeper than that. Here is my nuanced take. Let me break it down for you.
First, the RDA comes from short-term studies (typically 7 days in duration) and what you find for most studies is that they are done on college-age students. So for this age group, you have to bear in mind that they are at the end of their growth. The second point to make is that it is incredibly difficult to measure your protein intake and utilisation (in humans). Most scientists agree that whilst we can measure what we put into our bodies fairly accurately, the measurements of how protein is utilised or excreted out of the body are very complex, and we don’t have an accurate method to measure the output. So for these reasons, I often think about RDA for protein as a minimum amount.
The Recommended Dietary Allowance (RDA) for protein is a modest 0.8 grams of protein per kilogram of body weight. Think of the RDA as the amount of a nutrient you need to meet your basic nutritional requirements. In a sense, it’s the minimum amount you need to keep from getting sick — not the specific amount you are supposed to eat every day.
In our research, we believe that the amount we should be aiming for is around double that figure. And here is why.
We are now discovering that protein handling (efficiency) goes down as we get older. What I mean by this is the efficiency in which we convert proteins that we eat to energy and muscle mass creation goes down as we get older. So as we get older, now we have much higher requirements than the estimated RDA values based on college-age students.
To add on to this, as we get older, we do lose muscle more easily due to inactivity compared to when we are younger. Now I can attest to how easy this is. I think the problem is not to be underestimated. Most people probably just find themselves in this situation as they get older, they get busier with their jobs, they have kids, and they have family commitments, etc. There is less and less time for exercise and may be less time for proper comprehensive meal nutritional strategy, compounded by may be more sedentary work life, etc. Before you know it, you have gained some weight as fat, but you have probably lost muscle (so kind of a double whammy of badness) because of your inactivity and lack of exercise.
Scientific Rationale
There were a few so-called ‘bed rest’ studies that were done. They basically put people on prolonged periods of bed rest and measure changes in their body parameters, including muscle mass. They found that older adults lose lean tissue more rapidly than the young during prolonged periods of physical inactivity. It was found that approximately 3 to 6-fold greater rate of muscle loss in bed-ridden older adults compared to younger counterparts. If you are in a situation where you have to be in hospital for any reason, even planned surgery, for example, where you will likely need a prolonged period of bed rest. Do bear this in mid as this is definitely something you have to be careful and take into consideration.
To me that is frightening how fast you can lose it. And as we get older, it also becomes more difficult to put back and get back to where you are. You have to be really motivated and dialled-in in terms of upping your protein requirements optimised for anabolic response for muscle hypertrophy and timing that with targetted resistance training. I think it is hard, so it is much easier to try not to prevent muscle loss along the way, or at least be mindful of the issue.
Protein Quality
The second point I want to touch on is regarding the quality of proteins. Now recall we talked about the fact that proteins are made of amino acids. Think of these as building blocks and they are aggregated together in chains, to form big chunks of proteins. Now it turns out that there are different kinds of amino acids, and the important ones for our body are named ‘essential amino acids’.
Scientists think that around 9 essential amino acids are crucial for our body functions. These are listed here.
Histidine
Isoleucine
Leucine
Lysine
Methionine
Phenylalanine
Threonine
Tryptophan
Valine
Each plays different roles in our body. For example, Leucine has more metabolic roles in activating mTOR gene, whereas Arginine, for example, is important interaction with Nitric Oxide in our body.
Now the critical thing to note is that scientists now realise that actually to stimulate these important roles in our body, we actually need probably a lot more in terms of the amount of these compared to the RDA. When we think about vitamin C, for example, we know there’s a minimum RDA to prevent scurvy. Increasingly, scientists are advocating that we should probably be thinking about these amino acids the same way in the future. That is to say that there are different kinds of essential amino acids that we need, just like different kinds of vitamins that we need.
The composition of these amino acids that make up the proteins that we ingest is also important. Say if we eat a steak, do we have the right amount of all these essential amino acids? And the answer is yes. But for plants, unfortunately, the answer is maybe not. For example, when we look at the 3 essential amino acids (leucine, lysine, and methionine) we know that for some plants, they lack methionine whereas animal-based proteins will have all these 3.
Digestion and Absorption
If we eat say 10g of proteins, how much of that is actually absorbed into our bodies? And you may be surprised to know that this is different depending on the food that you take.
With animal proteins (e.g. chicken, beef) and most isolated proteins (e.g. in protein shakes), even soy protein isolates, the digestion and absorption is pretty close to 100%
For plant proteins it is less, maybe only 60-70% available because we can’t digest the fibre proteins are attached to. Plants have proteins attached to the leaves and the stems and the roots and the flowers and the seeds. When you eat plants in a raw form, only 60-70% of the protein is available because we can’t digest the fibres. For a wheat protein (i.e. wheat bran) scientists have discovered that the absorption is only around 40%.
“If you look at some wheat-based cereals and it states that there are 6 grams of protein per serving, there’s actually less than 3g of that which you can actually absorb”.
Now there is nothing wrong with eating plant-based proteins, but you may need to be aware that you need to eat more of it.
If you have 100-120 grams of protein per day, the distribution between animal and plant probably doesn’t matter, because you probably have enough to cover it. But, if you’re only eating 50 grams of protein per day then it makes a big difference, you’ll never catch up to your essential amino acid needs if you are just on plant-based diets eating 50 grams per day.
What do we recommend?
A good target is somewhere between 50 and 120 grams of protein, it depends on what you choose. If you’re going to be plant-based, have 125 grams of protein per day and you’re probably fine.
Timing
Now it’s not only the amount of protein that you take that is important but also when you should take it, particularly if you are looking at it through the lens of muscle synthesis and maintaining muscle. One of the important point to consider is that after an overnight fast, your protein synthesis state is already down and for a lot of people who does intermittent fasting for example, and skip breakfast, what you have to be quite careful about is that you are potentially prolonging that window of down-regulating protein synthesis to the extent that you are causing catabolic states where your proteins i.e. muscles are being used for fuels.
We see quite a lot of times, with people who do skip breakfast that sometimes they actually lose muscle mass, and over time, actually, their body composition gets worse. Sure they may be losing fat, but also they are losing muscle. To combat this, the first meal that you take, you should really ensure that you take enough proteins. And overall, the thinking now is that it is better to spread out your protein intake over 2-3 meals, rather than having a large protein boost in one meal and not the other. There is a lot of data now that the so-called ‘anabolic response’ ie. muscle synthesis state is optimum between 25 maybe 60 grams for an ageing adult.
Why is this important? Well, if you just have a protein bar that has 10g of protein, that is not going to cut it. You need to have at least 25g. This is basically down to leucine effects on mTOR signaling for muscle protein synthesis that we mentioned already. Leucine is one of those essential amino acids, and to activate mTOR signalling for muscle synthesis you really need to hit around that amount of protein. That’s also another consideration.
If you want muscle synthesis and muscle hypertrophy…
In the adult, say they eat 100 g of protein in a day but take it in very small meals - like 15 g trickled in all day long. This will never stimulate muscle protein synthesis. You need to trigger above a certain threshold like 25g or more to stimulate muscle synthesis.
So I hope that has been a useful overview of protein-focused nutrition through the lens of longevity. As always, if you have any questions, please leave them in our comments section.