The Age-related muscle loss, which doctors call sarcopenia, affects nearly 2 million French people[1]. It is a silent phenomenon that gradually sets in after the age of 50 and can have significant consequences on autonomy and quality of life.
We delved into this subject several years ago, particularly during our research for our book on algae. And frankly, what we have discovered in recent scientific studies is truly promising. The brown algae, consumed daily by the centenarians of Okinawa, could play a role in maintaining muscle mass. A clinical study published in 2024 in the journal Vieillissement et maladie provides particularly interesting elements on the subject[2].
Understanding Sarcopenia: When Our Muscles Silently Waste Away
The sarcopenia, it is this progressive loss of muscle mass and strength that accompanies aging. The term itself comes from the Greek sarx (chair) and penia (loss), and was first defined in 1989 by Irwin Rosenberg[3]. Specifically, from the age of 30, we lose approximately 3 to 8% of our muscle mass per decade[4]. And this phenomenon accelerates after the age of 60, potentially reaching 15% per decade according to some studies.[5].
Why is it concerning? Because our muscles are not only used for carrying groceries or climbing stairs. They play a fundamental role in our metabolism, balance, posture, and even our immune system.[6]. A muscle that wastes away is a body that becomes more fragile, more tired, and more vulnerable to falls and fractures. In fact, sarcopenia is now recognized as a major risk factor for falls in the elderly.[7].
The signs that may raise concern are relatively subtle at first: unusual fatigue, difficulty getting up from a chair without using the arms, a gait that becomes less steady, daily actions that require more effort than before. This is why this condition often goes unnoticed until it becomes truly problematic.
In reality, three main mechanisms are at play in this process.[1] :
- The decrease in muscle protein synthesis
- The increase in the degradation of existing muscle fibers
- The dysfunction of mitochondria, these small powerhouses present in each of our muscle cells
It is on this last point that recent research on the brown algae provide particularly interesting insights.
The Secret of the Centenarians of Okinawa
A few years ago, during a trip to Costa Rica in the province of Nicoya, we began to take a close interest in the blue zones, these regions of the world where there is an exceptional concentration of healthy centenarians. Okinawa, in Japan, is one of these fascinating places and is one of the five blue zones identified by researchers.[8].
What struck us is that the inhabitants of Okinawa consume on average 5 to 7 grams of seaweed per day[9]. This is considerable compared to our Western diet where seaweed is almost absent. And this is not insignificant: the Japanese from Okinawa have significantly lower rates of sarcopenia than Western populations of the same age.[10].
Of course, their overall lifestyle contributes to this. longevity : daily physical activity, a diet rich in plants, strong social connections. But the role of seaweed in their traditional diet, at the heart of the Okinawa diet, deserves our attention. The wakame, "the" Kombu, nori... these seaweeds are present in practically all their meals, from the morning soup to the evening dishes.
What is remarkable is that these populations maintain functional muscle mass much longer than we do. At 80 years old, many of them continue to garden, walk several kilometers a day, and lead an active and independent life. A study published in the Journal of the American Geriatrics Society showed that the centenarians of Okinawa maintained a grip strength 20% higher than their American counterparts[11].
The 2024 clinical study: encouraging results
In 2024, a study published in the scientific journal Vieillissement et maladie provided concrete data on the link between brown algae and muscle function[2]. Researchers studied the effects of an extract ofIshige okamurae, a brown algae, on adults over 60 years old experiencing muscle decline.
Here is what the study showed: after 12 weeks of supplementation With 500 mg per day of extract from this brown algae, the participants showed an improvement in their muscle strength, particularly in the quadriceps. This is a really interesting result because quadriceps strength is directly linked to the ability to stand up, walk, climb stairs - in short, to daily autonomy.
But the most fascinating aspect of this study is the explanation of the mechanism. The researchers highlighted that the active compounds in the algae, particularly the phlorotannins and the fucoidan, contribute to the proper functioning of mitochondria in muscle cells[2].
To put it simply: mitochondria are like small power plants in our cells. When they function well, our muscles have the energy needed to contract, regenerate, and stay fit. When they malfunction-a phenomenon that accelerates with age[12] - it is the entire muscle that gradually weakens. Brown algae seem to support this cellular machinery.
This study is not isolated. Other research has shown that fucoidan extracted from brown algae could help reduce muscle atrophy in experimental models.[13].
Why brown algae are particularly interesting
What distinguishes the brown algae like wakame or kombu, other sources of nutrients, it is their richness in unique bioactive compounds. These molecules are not found anywhere else in the plant kingdom.[14].
The fucoidan, for example, is a sulfated polysaccharide found exclusively in brown algae. Studies show that it is involved in several bodily functions, notably by supporting the immune system and helping to protect cells.[15]. The Fucoxanthin, this pigment that gives brown algae their characteristic color, is involved in energy metabolism and is the subject of numerous studies for its potential role in maintaining a normal body weight.[16]. As for the Phlorotannins, these are specific antioxidants found in algae that help protect cells against oxidative stress[17].
But beyond these specific compounds, the algae brunettes also bring:
- Of the plant proteins of quality, with an interesting amino acid profile for muscle maintenance
- Essential minerals such as iodine, calcium, magnesium, and iron are involved in the normal functioning of muscles.[14]
- B vitamins that contribute to normal energy metabolism
- Fibers that support our microbiota, which is itself linked to our muscle health as shown by recent research on the gut-muscle axis.[18]
Frankly, when we look at all these properties, we understand why populations that have been consuming seaweed regularly for generations exhibit different aging profiles.
