Scientists talk about the potential of spices in diabetes research
Turmeric, cinnamon, garlic and other familiar foods contain substances that can affect the processes associated with the development of diabetes. However, the results of laboratory experiments and small clinical studies do not yet allow them to be considered a proven treatment. This is the conclusion reached by researchers at Texas Tech University who analyzed scientific papers on natural compounds and metabolic disorders. Why scientists are interested in common seasonings, what studies of curcumin have shown, and why honey cannot be considered an absolutely useful substitute for sugar in diabetes — in the Izvestia article.
Diabetes doesn't just affect sugar levels.
An increased concentration of glucose in the blood is the most well—known sign of diabetes. But it has a whole range of disorders that affect cell function, fat metabolism, and inflammatory processes. It is these relationships that have become the basis of the new review.
The authors consider two main types of the disease. In type 1 diabetes, the immune system destroys the cells of the pancreas that produce insulin. In the second type, tissues react worse to this hormone, and the body's ability to produce it may decrease over time. Most of the studies of natural substances included in the review belong to the second type. It is impossible to transfer their results directly to the first type of disease.
With prolonged metabolic disorders, cells can be damaged due to the accumulation of certain lipids. At the same time, oxidative stress occurs: reactive oxygen species are formed in quantities that the body's defense systems cannot cope with. This contributes to the damage of proteins, fats and DNA.
The review also examines disruptions in the functioning of mitochondria, which provide cells with energy, and the endoplasmic reticulum, which is involved in the formation and processing of proteins. These processes help explain why the effects of diabetes are not limited to changes in a single indicator in a blood test.
Therefore, scientists are studying compounds that can affect several mechanisms of the disease at once. Natural substances attract attention for their biological activity, but the ability to influence the cellular process does not mean that a drug based on them will improve human health.
What exactly did the researchers study
The new work is a narrative review. The scientists summarized publications on cellular experiments, rodent studies, and clinical trials involving humans. This format allows us to compare different areas of research and describe the proposed mechanisms of action. At the same time, the authors did not carry out a formal selection according to the rules of a systematic review and did not calculate the overall effect of all interventions in their own meta-analysis. Therefore, the work shows the state of scientific research, but does not establish a unified assessment of the effectiveness of natural remedies.
The focus was on curcumin, honey, culinary spices and some traditional medicine preparations. Among the spices, the researchers examined garlic, fenugreek, cumin, coriander, ginger and cinnamon. Shilajit, also known as mummie, and guduchi, the Tinospora cordifolia plant, were discussed separately.
The authors compared data on the effects of these substances on inflammation, antioxidant protection, insulin sensitivity, and pancreatic cell safety. They also studied the mechanisms that allow glucose to enter cells, including the movement of the GLUT4 transporter protein to the cell membrane.
To interpret the results, it is essential where exactly the effect was observed. A change in protein activity in a cell culture, a decrease in glucose in a laboratory animal, and an improvement in a clinical trial provide different levels of evidence. To reduce them to the general statement "spices help with diabetes" would be incorrect.
Curcumin: why the form of the substance is important
One of the most thoroughly studied compounds was curcumin— a component of turmeric. In experimental models, it affected signaling pathways associated with inflammation and antioxidant protection. In particular, the researchers described the suppression of the activity of NF-kB, involved in inflammatory reactions, and the activation of Nrf2, which regulates the protection of cells from oxidative damage.
In some preclinical studies, the effect of curcumin was accompanied by an increase in the activity of antioxidant enzymes and a decrease in the programmed death of pancreatic beta cells. It is these cells that produce insulin. However, observations in experimental models do not prove that regular turmeric is able to preserve their function in patients.
There are also studies involving humans. In one clinical trial published in 2016, 70 adults with type 2 diabetes received a nanomicellar form of curcumin at a dose of 80 mg per day or a placebo for three months. At the same time, the participants continued the necessary drug treatment: the substance was tested as an adjunct to therapy.
The study showed an improvement in glycated hemoglobin HbA1c, an indicator reflecting glucose levels over the previous months. However, the difference between the fasting glucose groups was not statistically significant. Therefore, the results should not be described as an equally convincing improvement in all indicators of carbohydrate metabolism.
It is also important that a special form of substance delivery was used in the test. Regular curcumin has a low bioavailability: after ingestion, it is rapidly metabolized and excreted. The results for the nanomicellar form cannot be automatically transferred to other additives or to turmeric, which is used in cooking.
A small sample and a three-month follow-up period also limit the conclusions. Such a test alone does not provide an answer as to whether the intervention reduces the risk of vascular complications and whether it is safe with prolonged use.
Cinnamon, garlic and fenugreek: the results vary
The data on culinary spices turned out to be heterogeneous. The studies varied in the composition of drugs, dosages, duration of administration, and characteristics of participants. Even if positive changes were found in individual works, this did not mean that the same effect would occur when using any product with that name.
Fenugreek has been studied, in particular, because of the compound 4-hydroxyisoleucine contained in it. Experimental data indicate that it can stimulate insulin secretion depending on glucose concentration. In some small clinical trials of fenugreek preparations, a decrease in fasting and post-meal sugar was also noted.
However, these observations do not yet allow us to determine a universal application scheme. To do this, it is necessary to determine which composition gives a reproducible effect, how pronounced it is and whether it persists with longer observation.
In the case of garlic, sulfur-containing compounds, including allicin, attracted the attention of scientists. In experimental models, garlic preparations reduced oxidative damage to lipids, and in some clinical studies, a moderate decrease in cholesterol was noted. These results relate to specific interventions and indicators, so they do not serve as evidence that eating garlic prevents diabetes complications.
For cinnamon, the authors reviewed, among other things, a meta-analysis of 24 randomized controlled trials. The results of individual studies of its effect on glucose control and insulin resistance varied.
The US National Center for Complementary and Integrative Health also points out that research on herbal supplements for diabetes is limited in number of participants and quality. Differences between drugs and regimens make it difficult to draw conclusions about their effectiveness. In addition, supplements may interact with sugar-lowering medications, so their use should be discussed with your doctor.
Why honey doesn't become a medicine due to antioxidants
Honey has taken a separate place in the review. It contains polyphenols and other compounds that exhibit antioxidant and anti-inflammatory activity. However, honey is also a source of large amounts of carbohydrates. It is impossible to consider only one of these characteristics when assessing its effect on diabetes.
Therefore, the review does not provide any reason to use honey without restrictions instead of regular sugar. Its natural origin alone does not make such a replacement neutral for glucose levels.
This example shows the general complexity of food research. The properties of a single substance and the effect of the entire product may vary. To evaluate the result for a person, it is necessary to take into account the composition, quantity and conditions of use, and not only the presence of compounds with potentially useful activity.
Traditional remedies: questions about effectiveness and safety
The authors evaluate traditional medicine drugs even more carefully. Preliminary results related to antioxidant activity and possible effects on metabolism are described for guduchi and shilajit. However, a significant part of this data was obtained in experimental studies.
There is no sufficient clinical basis for their use in the treatment of diabetes. However, safety issues remain: the review mentions reports of liver damage associated with guduchi and concerns about potentially toxic metals in some shilajit preparations.
This does not mean that any product will necessarily cause such consequences. However, without control of the composition and full-fledged research, a remedy cannot be considered safe just because it has a natural origin or has been used in traditional practice for a long time.
For patients with diabetes, the safety assessment is especially important, since supplements can be used simultaneously with prescribed medications. According to the American National Center for Complementary and Integrative Health, untested remedies should not replace medical treatment.
What needs to be proven before applying
The main perspective described in the review is related to the further study of specific compounds. Scientists need to standardize the chemical composition of drugs, address the delivery of active substances, and verify the results in large, multicenter, randomized trials.
Studies should evaluate not only changes in laboratory parameters, but also results that are significant for patients, as well as safety with prolonged use. So far, there is insufficient evidence that the described effects of natural substances prevent vascular damage in people with diabetes.
The task is also to determine whether such interventions provide additional benefits against the background of standard treatment. A positive result of a cellular experiment may be the basis for a new study, but a much more complete verification is needed to prescribe it to patients.
Curcumin, garlic and fenugreek compounds remain objects of scientific interest. However, the practical significance of these studies will depend on whether their effectiveness can be confirmed for specific drugs, doses, and patient groups. Prior to this, familiar spices should be perceived as food products, and reports of their medicinal potential should be interpreted as information about an ongoing scientific search.
Переведено сервисом «Яндекс Переводчик»
