Beta-glucans have an important place as a structural components of certain cells as well as their indisputable function to preserve human health. They belong to the carbohydrates family, which makes up one of the four basic pillars of organic chemistry, and thereby, of life itself (the other three would be proteins, lipids and nucleic acids).
Their structure is that of a typical complex carbohydrate, which consists of long chains made up by thousands glucose molecules. These molecules are connected by what is known as glycosidic bond in biochemistry, in which the oxygen atom connects the two glucose molecules.
The multiple branches of these chains, provide this substance with a three-dimensional configuration and a high molecular weight.
If we were to summarize the personality of the beta-glucans as precisely as possible, we could say that they are natural stimulants of the immune system. Their therapeutic properties have been used by Eastern civilizations for over two thousand years. Western culture would not start to do so until the second half of the 20th century.
As we will see, its enormous potential has given beta-glucans a place of recognized prestige among the substances that help to treat a lot of diseases, including certain types of cancer.
Where can they be found?
The anatomic element that is connected to the presence of beta-glucans is the cell wall. Beta-glucans provide the firmness it needs so that the cells are capable of performing their functions.
But, which are these cells? Naturally, all those that belong to the animal kingdom are excluded, which means that we are talking about:
- Vegetables, which allow the cells to support the tissues. The beta-glucans that make up the cell wall of plants behave as soluble fiber.
- Yeasts, which are fungi that are made up of a single cell that is fermented by simple carbohydrates or sugars, producing different substances as metabolic products.
- Fungi, including mushrooms.
- Some species of seaweed.
Those beta-glucans that are present in brewer’s yeast (Saccharomyces cerevisiae) and a group of species of mushrooms belong to those beta-glucans that are not fiber-soluble. This means that they have more biological activity, some of them are:
- Reishi: a mushroom that is commonly described as woody, bitter and endowed with chemicals with an anticancer activity which supports the strength of the immune system. In addition, it provides an organic form of germanium that is highly beneficial for health.
- Shiitake has a component called lentinan (a beta-glucan) which strengthens the body’s defenses against viruses and tumor cells.
- Maitake or imperial fungus, a mushroom with an excellent flavor that was highly valued in medieval times for its ability to prolong life by increasing the resistance to diseases.
- Matsutake, also known as the “pine mushroom”.
On the other hand, the fiber-soluble feature is related to the beta-glucans. They provide cohesiveness to the cell walls of the husk from cereal grains, mainly oats and barley.
The main natural sources of Beta-glucans
We can make a list with some of the most substantial natural sources of beta-glucans based on the previous description about the location of these substances. In this way, we will be able to benefit from their medicinal properties:
- Brewer's Yeast and barley: Rich in beta-glucans, especially suitable for strengthening the immune system and regulating the cholesterol.
- Mushrooms from the species that have been previously mentioned: Their beta-glucans have been regarded as an effective supplement to combat colon cancer.
- Oats: Exceptionally endowed with beta-glucans that are effective to regulate two fundamental parameters in our metabolism: cholesterol and blood glucose.
Oats are a cereal that perhaps has not yet managed to gain the consideration it deserves within the human diet. But in spite of its precarious position as an ingredient or food, it has a good press among nutritionists and people who follow strict diets.
But there is no doubt that part of its good reputation is due to the fact that it contains a functional ingredient (a term derived from the European Union legislation on new foods, new ingredients and functional ingredients and foods).
The functional ingredient of oats is beta-glucans, a type of soluble fiber that is also highly abundant in the chemical composition of barley. However, the latter is restricted to animal food and oats have gained the role of the natural source of beta-glucans for humans.
This circumstance has increased the interest of the agri-food industry in including oats, particularly their outer husk that is also called bran, in different production lines such as: the production of extruded oat flakes, a range of cereal flakes, nuts and dried fruits known as muesli, or the popular multi-cereal flours used as raw material for the preparation of special breads and biscuits.
One of the virtues of oat bran is that, unlike what happens with other cereals, it is practically tasteless and feels soft to the palate. This results in an absolute neutrality for the average consumer.
The European Food Safety Authority (EFSA) of the European Union carried out a battery of tests for the evaluation of beta-glucans and concluded that their ability to regulate blood glucose and cholesterol was sufficiently proven. However, it had to be combined with a series of requisites.
But in order to give us a complete idea of the credibility of beta-glucans as molecules for medicinal purposes, we will point out that, apart from the EFSA’s opinions (which may already be enough) other institutions linked to the world of nutrition and food safety have gone further in their recognition of the role of these carbohydrates in minimizing the risk of coronary heart disease related to high cholesterol or diabetes.
Some of these institutions are: the Food and Drug Administration (FDA) of the United States, the Health Department of Canada or the Food Standards Agency of Australia and New Zealand.
Properties and benefits of beta-glucans
The first thing that should be clear is that the concentration of beta-glucans in a product does not say anything about the properties of these substances. To provide an absurd example, take a roll of kitchen paper which has a composition of a 99% of beta-glucans, technically, it should be the best natural source of this carbohydrate, which is obviously false.
So the question we must ask ourselves is: what is truly determinant in the biological effectiveness of beta-glucans?
For example, for the aforementioned varieties of mushrooms, the key aspect is that they are bound by very specific glycosidic bonds and that this two-dimensional structure is rolled up in a triple helix, similar to what happens in the three-dimensional structure of DNA.
This detail seems to be the key that determines that the beta-glucans present in fungus are the ones that interact the most with the cell receptors to trigger the immune response. To illustrate this process, we could compare it to a key that activates a mechanism when it opens a lock.
Additionally, there are other aspects that condition the properties of these carbohydrates, like the number of triple helixes, whether they remain intact or damaged, the molecular weight, the branching intensity of the glucose chains, their possible bonding to other macromolecules, like proteins…
For all of these circumstances, it is clear that the amount of beta-glucans contained in a food is a value that does not provide enough information in terms of their quality between different sources.
Therefore, the supply of a modest amount of beta-glucans of a high biological value is much more effective than a high quantity with a low quality.
Experts on the matter agree on the fact that the biological quality is greatly conditioned by the size of the beta-glucan molecules, in an inversely proportional manner. This means that a smaller size implies a better absorption and higher bioactivity.
But if we are to do justice to the effects of beta-glucans on health, we can not ignore that:
- They have an immunomodulating effect, which is perhaps its main medicinal effect on the organism.
- They produce an antioxidant effect that contributes to reducing the formation of the free radicals in the cell membranes.
- They help to reactivate the generation of new blood cells when the production has been disrupted due to chemotherapy or radiation therapy in cancer treatments.
- They accelerate the healing of wounds and burns. Particularly, combining beta-glucans with collagen creates a coating for first and second degree burns with good results.
- They have a triple effect on the bowel: they prevent constipation by increasing the peristalsis, stimulate the population of beneficial bacteria (a prebiotic effect) and reduce the risk of colon cancer.
Now, we will proceed to asses the main benefits separately.
Beta-glucans: an excellent modulator of the immune response
One of the remarkable properties of beta-glucans is their therapeutic ability as an immunomodulator. The intensity of the response is not produced by the amount of beta-glucans that are supplied to the organism, rather by their molecular type and their source. These factors, as we previously explained, condition their bioactivity significantly.
The following scientific research article The effects of beta-glucans on human immune and cancer cells that was published in 2009, described how beta-glucans are able to enhance the machinery that is in charge of producing several cell lines of the immune system, namely macrophages or giant cells, neutrophils, mononuclear cells, natural killers or NK cells, and dendritic cells.
This results in the body’s immune response to external and internal aggressions which, at a first, will be visible in a stimulation of phagocytosis (a phenomenon in which macrophages trap and destroy foreign substances, including tumor cells).
Another study reached similar conclusions a year later in the World Journal Clinical Oncology , which showed how beta-glucans, a group of biologically active natural compounds known as biological response modifiers, could be the most relevant natural immunomodulator discovered to this date. More specifically, immunologists at the University of Louisville discovered the existence of a receptor on the surface of the defense cells, called CD3, to which beta-glucans would bind.
Among other areas of research on this subject, we will mention one that is focused on the use of beta-glucans against the so-called environmental immunosuppressants. It provisionally grants beta-glucans and their combination with certain substances the ability to neutralize harmful substances that are present in the water and atmosphere such as methylmercury or fluorinated hydrocarbons. If this is confirmed, beta-glucans would gain a place in the treatments to prevent the chronic poisoning of the immune system.
Control glucose levels in the blood
The ability of beta-glucans to buffer the oscillations in post-meal glucose levels (what is technically called postprandial glycemia) and their preventive action against the onset of type 2 diabetes are two fields of work where much progress has been made in the last decade, providing highly relevant conclusions in favor of these substances.
We will begin by reminding what is the glycemic index of a food. This value gives information about the behavior of the product in relation to the rate of intestinal absorption of the carbohydrates in its composition.
If this is already important for any organism, it is even more in the case of diabetic people, who need to avoid foods that cause a fast increase of sugar in the blood: these are foods that have a high glycemic index.
In this context, what is the effect of the beta-glucans on this metabolic phenomenon? To put it simply, they can reduce the glycemic index of the foods that contain carbohydrates and this flattens the curve of postprandial glucose, even in people with diabetes.
Consequently, eating foods that have a low glycemic index, including oatmeal or legumes, may help to control diabetes.
Benefits against hypercholesterolemia
One thought-provoking fact is that, for the World Health Organization, more than two and a half million deaths each year are linked to high levels of blood cholesterol. The major cause of those deaths is the coronary heart disease. If we limit the numbers to the scope of our country, the statement released by the National Institute for Health and Clinical Excellence (NICE) of the United Kingdom confirms that more than half the population is affected by hypercholesterolemia, this data is not very encouraging, and it places this disorder among the main concerns of health authorities.
According to a report published in 2011 by Nutrition Reviews, consuming beta glucans regularly, according to the dose that will be discussed below, is able to reduce the cholesterol levels in a 5% and low density lipoproteins or LDL in a 7%.
Many experts believe that the action mechanism of these substances is the formation of a viscous layer on the mucosa of the small intestine.
This layer hinders the absorption of the cholesterol and triglycerides ingested through food. It produces a screen effect for the absorption of cholesterol by blocking the access to its membrane receptors in the intestinal cells. On the other hand, it becomes an obstacle for the re-absorption of bile acids which are the raw material for the synthesis of cholesterol, the so-called endogenous cholesterol.
The organic response to this double action consists of enhancing the synthesis of bile acids from the circulating cholesterol. Hence, slowing down the intestinal absorption of cholesterol and a fast withdrawal of endogenous cholesterol to synthesize bile acids leads to the previous results.
Beta-glucans and other diseases
The multiple attempts to confirm the therapeutic possibilities of beta-glucans against one of the main global health problems, cancer, provided satisfactory results decades ago in several research areas. Its anti-tumor activity has been proven in many types of cancer, particularly breast, lung, stomach and colon cancer.
Among the numerous studies on the subject, we will mention a paper that was published in 2007 by the Lithuanian University of Health Sciences which postulated that beta-glucans prevent the oncogenesis (the formation of malignant tumors) by deploying protection mechanisms against powerful carcinogens enclosed in genetic factors of the body itself.
In order to clarify the role of these substances in relation to cancer, we will make the following scheme:
- They enhance the cytotoxicity of natural killer cells (NK), which leads to the inhibition of the excessive growth of tumor tissues and a delay of the metastases.
- They increase the efficacy and reduce the toxicity of chemotherapy and radiotherapy treatments. This is due to their contribution to regulate the process of synthesis and maturation of white and red blood cells and platelets in the bone marrow, a process that is usually deteriorated during said treatments.
- They protect the macrophages (cells of the first line of defense) from the oxidizing action of the free radicals during the irradiation, which allows them to preserve their functionality.
- They have revealed an interesting synergy with monoclonal antibodies in anti-tumor treatments.
- Some, like the lentinan of the Shiitake fungus or the polysaccharide-k, have been successfully used in anti-cancer therapies for several decades.
- In patients who suffer from advanced stomach cancer, a combination of Shiitake’s beta-1,3-glucan with chemotherapy has been shown to significantly prolong the lifespan of these individuals.
Other possible therapeutic applications
We will give two examples in order to illustrate this point:
- Researcher Gary Ostroff of the University of Massachusetts works on the utility of these polysaccharides against anthrax, one of the most lethal infections for humans.
- Dr. Nino Sorgente of the University of Los Angeles leads a research line about osteoporosis and bone loss, that studies the possibility of using beta-glucans in order to select the cells that form the bones matrix, called osteoblasts, at the expense of the destroyers, the osteoclasts.
Interest in beta-glucans supplementation
Apart from being present in foods, which are natural sources, beta-glucans are sold as dietary supplements.
Those who support their consumption point out that a systematic supplementation of this substance can have a positive impact on controlling or healing health problems such as:
- Crohn’s disease
- Chronic Fatigue Syndrome
- Rheumatoid arthritis
- Ulcerative colitis
Apart from this, they claim that beta-glucans balance the effects of oxidative stress caused by doing physical exercise.
How to achieve the recommended daily dose of Beta-glucans?
The recommended daily amount is around 3 grams, a number that can be reached through the consumption of a variety of foods that contain oats, as bran, flakes, bread, toasts, muesli with oat flakes, and oatmeal cookies or bars.
Consuming 3 grams of betaglucans daily (which equal about 75 grams of oat flakes and 40 grams of bran) seems to be a dose with the capacity to reduce the cholesterol levels in the plasma and “bad cholesterol” (low density lipoprotein or LDL) by a 5-10%, respectively, within a few weeks.
It is advisable for people with diabetes or who at risk of suffering this disease, like obese people, to consume a daily amount of 4 grams of beta-glucans, preferably oats, for every 30 grams of carbohydrates. This amount can be reached by means of 2-4 servings per day of products made with this cereal (such as breakfast cereals, special breads or biscuits).
It is especially beneficial for non-insulin-dependent diabetic people to eat them for breakfast, because it is the perfect moment to contribute to a constant and adequate level of glucose in the blood.
On the other hand, it seems to be a hypotensive factor in people with severe obesity.
How to consume Beta-glucans
When these substances are consumed as a dietary supplement dissolved in a liquid matrix, such as milk or juice, they seem to be more effective than when they are consumed as solid foods made from oats. The explanation lie in the fact that the three-dimensional structure of beta-glucan molecules tends to be denatured during the processing of the oats. This negatively affects two basic properties: molecular weight and viscosity.
It is also convenient to keep in mind that their absorption is enhanced when they are taken on an empty stomach.
How to purchase Beta-glucans
Beta-glucans supplements are available in the market, both online and in specialized dietary supplement stores. Many of these are made from bakery yeast or brewer’s yeast. Others use medicinal fungus, like shiitake or maitake, that we mentioned at the beginning of this article.
The efficacy of beta-1,3-glucans as immunomodulators has been so widely proven that the nutraceutical industry has patented combinations with substances such as vitamin A, ascorbic acid or keratin, among many others, under the name of “immunological enhancers”.
Industrially, the critical compounds of the soluble fiber or yeast are extracted, according to the raw material in question, eliminating the fats and proteins to obtain a purified extract, which represents the beta-1,3-glucan. Then, they are packaged in tablets and capsules.
Side effects and contraindications
In general, the intake of beta-glucans from yeast and fungi seems to be optimally tolerated, since they have been reported to have very residual adverse effects. In fact, they belong to the group of substances known as GRAS (generally recognized as safe) in the United States.
The use of concentrated supplements is not advised for pregnant and lactating women, due to lack of studies that ensure their full safety, although the beta-glucans consumed through food should not produce side effects.
Finally, it is necessary to list some circumstances that may have consequences for our health:
- It is known that the simultaneous administration of aspirin or non-steroidal anti-inflammatory drugs (e.g. ibuprofen) together with beta-glucans is likely to cause severe gastrointestinal injuries with the possible complication of peritonitis, that can have a serious consequences.
- In some cases, the intravenous administration has caused: headaches, dizziness, vomits, diarrhea/constipation, allergic skin reactions, blood pressure alterations, and excessive diuresis.
- Those who take anti-hypertension drugs or usually have a low blood pressure, should be careful when taking beta-glucans.
- At the same time, those who intend to take these supplements should consult their doctor, just in case they suffer from hypoglycemia or take medicines to lower the blood sugar levels, as well as if they are thinking about taking them to support the treatment of a chronic disease.
- As for the use of beta-glucans on the skin or subcutaneously (injected under the skin), there is not enough data to make an assessment.
On the contrary, it should be noted that the combination of beta-glucans with substances such as quercetin, selenium, vitamins A, C and E and alpha lipoic acid, can enhance their natural antiviral potential.