Abstract
Depression is one of the major health problems of our world. Recent studies have revealed the relationship between diet and depression. In Iranian traditional medicine, there is a therapeutic diet that is recommended in melancholic diseases like depression. One of the main components of this diet is meat. Meats are divided into 2 groups: recommended and abstinent. The aim of this study was to clarify the logic of this diet through comparing nutritional elements of the 2 groups with each other. For this purpose, prominent books on Iranian traditional medicine were searched for abstinent and recommended meats traditionally prescribed for depressed patients. The results of each group were compared with the other by using Mann-Whitney Test (SPSS version 16). The results showed that recommended meats contain higher amounts of polyunsaturated fatty acids (P = .01) especially omega-3 (P = .03). Both groups contain high amounts of cholesterol. Iranian traditional medicine recommends consumption of meats that contains cholesterol with omega-3 fatty acids in depression.
Depression is one of the major health problems and is among the first 10 diseases that impose the highest burden worldwide. 1 It is among the first 3 causes of burden in Iran. 2 It is highly prevalent among both developed and developing countries 3,4 and therefore, investigating solutions to prevent or treat depression has been widely considered in recent decades.
In spite of heavy investments on antidepressant drug development, the prevalence of depression is on the rise. 5 Recent studies have revealed the relationship between diet and depression. 6 –9 These studies indicated that some traditional diets like Mediterranean diet reduce the incidence of depression. 6,7 These kinds of diet consist of high amount of vegetables, fruits, whole grains, and fish and low amount of red meat and saturated fats. On the other hand, Western diet, which contains fried and processed foods, has been shown to increase the risk of developing depression. 8,9 The results of these studies, however, are not clear enough to codify an antidepressant diet 10 and more investigations on diet and depression are required.
In Iranian traditional medicine, preponderance of melanchole (black bile) in body organs is supposed to be the main cause of melancholic diseases. Recent studies reveal that clinical manifestations of melancholic diseases are in connection with some of today’s well-known mental disorders like depression (Table 1). 11 Iranian traditional medicine suggests a therapeutic diet for this kind of disease. 12 The footstone of this diet is to abstain from heavy, salty, salt-cured, and black bile–producing (melancholic) foods; and to recommend light and black bile–expellant foods. 11 This diet has a special consideration on the role of meats in prevention or treatment of melancholic-based diseases. Based on this diet, beef, pork, and most of the game meats have been banned because they are supposed to be black bile producing, and on the other side, lamb and some poultry meats have been recommended because they are digested to good chyme. 12 This diet is completely different from those previously studied, and no investigations have been done on it, yet. In this study, we tried to clarify the logic of traditionally recommended diet through the study of its nutritional elements.
Comparison Between Signs and Symptoms of Major Depressive Disorder and Preponderance of Melancholy in the Brain.
Abbreviation: DSM-IV TR, Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision.
Methods
To study the traditional antidepressant recommendations on meat consumption, prominent books on Iranian traditional medicine, including Al-Hawi (Rhazes, 10th century), Canon of Medicine (Avicenna, 11th century), Zakhire-ye-Khawrazmshahi (Jorjani, 12th century), Moalejat (Aqili Khorasani, 18th century), and Exir-e-Azam (Chishti, 19th century) were searched for recommended and abstinent meats traditionally prescribed for patients afflicted by depression. 13 –17
To quantify the results, the nutrients of each meat were extracted from the database of the United States Department of Agriculture. 18 If a meat did not exist in the United States Department of Agriculture list, its nutrient factors were searched in articles instead through Scopus. The content of fatty elements per 100 g of each recommended meat was compared with that of the abstinences’ and statistically analyzed by Mann-Whitney test via SPSS (version 16). P < .05 was considered significant.
Results
Recommended and abstinent meats extracted from Iranian traditional medical books are presented in Table 2. All major constituents of both groups were similar (Table 3). The only meaningful difference was in the amount of polyunsaturated fatty acids (P = .01) in which, the portion of omega-3 fatty acids in recommended meats was significantly greater than this factor in abstinent meats (P = .03) (Figure 1). The amounts of omega-6 fatty acids were not statistically different from each other.
Kind of Meat Based on Iranian Traditional Medical Texts (USDA Database Codes Are Also Presented).
Abbreviations: NA, not available; USDA, United States Department of Agriculture.
Main Nutritional Factors of Recommended and Abstinent Meats.
Abbreviations: MUFA, monounsaturated fatty acid; PUFA, polyunsaturated fatty acid; RAE, retinol activity equivalent; SFA, saturated fatty acid.
a P < .05.
Omega-3 and omega-6 fatty acid contents of recommended and abstinent meats. Omega-3 fatty acid was significantly higher in recommended meats than in abstinents but there was no statistical difference between omega-6 fatty acid content of the 2 groups. *P < .05.
Discussion
Iranian traditional medicine has been built on the humor theory. This theory attributes the occurrence of many diseases to humeral problems. 19 Depression, based on this theory, is attributed to excess of black bile in the brain and therefore, therapeutic approach—medicinal or nonmedicinal—is based on the solutions in which the entrance of black bile to the body is limited, and the excessive black bile of the brain is evacuated. 12 Traditional dietary recommendations are based on this therapeutic approach, that is, to limit eating black bile–producing foods and to nourish the body with special foods that are digested to proper humor. Meat as one of the main components of Iranian cuisine is included in these recommendations. In the case of depression, the consumption of black bile–producing meats, either red or white meats, is a red line. However, meat consumption should be continued but in the way which the Iranian traditional medicine recommends. Beef, duck, goose, and most of game meets are bad because they are digested to black bile; and lamb as a red meat and chicken, pheasant, and pigeon as poultry meats are good for depression because they are digested into good humors to be substituted with excessive black bile in the brain. If we try to translate traditional descriptions of meats to new medical terms, the best translator would be nutritional factors.
The main parts of all meats are protein and fat 18 and therefore, the first step of analyzing nutrients was to compare these factors in recommended and abstinent meats. Our results suggested that there are no differences between these factors and the energy released from. The second step was to study the elements of fats and proteins, that is, fatty acids and amino acids. Our results revealed that the amounts of polyunsaturated fatty acids are significantly more in recommended meats than the abstinent ones. Polyunsaturated fatty acids consist of 2 main kinds of fatty acids, namely, omega-3 and omega-6. Further analysis showed that omega-3 fatty acid is responsible for this difference.
Several animal and clinical studies has indicated that omega-3 fatty acids have anti-inflammatory properties and, therefore, might be useful in the management of many diseases including coronary heart disease and major depression. 20 Deficiency in dietary omega-3 fatty acid has been also shown to have some roles in the pathophysiology of several major psychiatric disorders. 21 Meta-analyses of randomized controlled trials demonstrated a statistically significant benefit of omega-3 fatty acid in unipolar and bipolar depression. 22 An Iranian clinical trial showed that daily intake of 1000 mg eicosapentaenoic acid (a kind of omega-3 fatty acid) or 20 mg fluoxetine for 8 weeks had equal therapeutic effects in major depressive disorder. This study also showed that eicosapentaenoic acid + fluoxetine combination is superior to either of them alone. 23 The better effect of combination therapy of omega-3 fatty acid and a selective serotonin reuptake inhibitor antidepressant (citalopram) was also shown in another clinical trial. 24 A recent human trial indicated that antidepressant activity of omega-3 fatty acid may be through dopaminergic system. 25
Here, we should also comment about cholesterol. Cholesterol is not found in significant amounts in plant sources. The main source of cholesterol is animal products. When Iranian traditional medicine recommends meat consumption for depression, it means that presence of this molecule is allowed in prevention or treatment of depression. Several recent studies have shown that low cholesterol is associated with depression. 26 –28 Partonen and colleagues 26 in 1999 published the results of their prospective study on the relationship between total cholesterol and mood. They followed 29 133 men aged 50 to 69 years for 5 to 8 years and found that low serum total cholesterol was associated with low mood and subsequently a heightened risk of hospital treatment due to major depressive disorder and of death from suicide. 26 A review article that had reviewed 40-year publication of the relationship between cholesterol and depression revealed that low cholesterol is related ro major depression. 27 The association of low cholesterol and major depression has also been shown in Iran, where the antidepressive diet of this article comes from. 28 Furthermore, it is now partly clarified that the relationship between statins and depression is because of decreased cholesterol levels. 29 Previous animal studies indicated that cholesterol has a role in 5-HT1A receptor functions. 30,31 5-HTA1 receptor as a serotonin receptor influences various neurological processes including depression. In an animal study conducted in 2015, it was shown that oral intake of cholesterol can reverse depression via 5-HT1A receptor and a 5-HT1A antagonist can block its effect. 32 Thus, a dominant feature of recommended meats to have high cholesterol and omega-3 fatty acid can be the key point of recommending these meats in depression.
As a conclusion, traditional recommended meats like other meats are rich of cholesterol but what distinguishes this group of meat from the others is the higher amount of omega-3 fatty acid. Recent investigations have suggested that low cholesterol and low omega-3 fatty acid are associated with depression. Therefore, traditional recommended meats are logically beneficial for depression. Clinical investigation on these meats will be fruitful.
Limitations
There was no information about some of the meats mentioned in Iranian traditional medicine diets in United States Department of Agriculture food database or other sources; giraffe, zebra, and gray partridge meat are examples. Thus, there is no study on them in this approach.
Footnotes
Acknowledgments
The authors would like to thank Dr Sayid Mahdi Mirghazanfari for his valuable contribution.
Author Contributions
Study concept and design: All the authors. Acquisition of data: MMA-A. Analysis and interpretation of data: AK, MMA-A. Drafting of the manuscript: MMA-A. Critical revision of the manuscript for important intellectual content: AT, AAN, MK.
Declaration of Conflicting Interests
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This study was supported by Elite Office, AJA University of Medical Sciences, Tehran, Iran, as a part of military services of Mohammad Mahdi Ahmadian-Attari.
Ethical Approval
This study did not warrant institutional review board review as no human subjects were involved.