Synergy is a concept with which most of us are familiar. The texts on labels of dietary supplements often proclaim “synergistic effects”— indeed, so often that synergism sometimes is described as the most over-used term in the industry because synergy commonly is claimed where none exists. More interesting, and arguably far more important, are nutrient and related interactions that might seem to fall under the heading of synergy, yet in reality are quite different. One such type of interaction that is gaining traction in the world of biochemical and medical research goes under the heading of the entourage effect. Whereas synergism involves components each of which is active on its own and which in combination yield effects greater than the sum of the individual contributions, the entourage effect may involve components most of which on their own may exhibit little or no benefit or may yield benefits that are otherwise unrelated. The entourage effect as a concept helps to explain why nutrients often behave very differently in different circumstances, why seemingly identical clinical trials may yield contradictory findings and other anomalies that we meet all the time in medicine and nutrition.

Synergism—the combined effects of two or more components is greater than the sum of the effects of the individual components acting alone

Many years ago, I was involved in the development of patentable forms of grape seed extract and their proanthocyanidin active components. We were exploring, among other things, how plant compounds work together with traditional antioxidant vitamins to provide protection that is superior to that of vitamins alone. People whose diet is rich in fruits and vegetables consume not only antioxidant vitamins, but also various polyphenols. Our starting point was that many of the benefits derived from eating such diets may be the result of synergism between the plant polyphenols and the better-known vitamin antioxidants. Plant polyphenols in this consideration were active antioxidant compounds, such as those found in tea, wine and grape juice. Overwhelming evidence supports the belief that excessive oxidation and free radical damage is linked to various disease states and even to aging. Yet studies in both animals and humans in which diets have been supplemented with antioxidant vitamins for long periods of time have yielded ambiguous results.

At the 219th American Chemical Society National Meeting held in San Francisco on March 26–30, 2000 researchers associated with the company Polyphenolics presented studies that supported supplementing the diet with special plant-derived nutrients and consuming more whole fruits and vegetables. One of our associates pointed out that antioxidant vitamins are present in the human body at levels typically twenty to several hundred times the level of plant polyphenols. This is one reason that so much less research has focused on the antioxidant vitamins in foods and relatively little research has been done on the antioxidant roles of the other compounds present. By 2000, however, it already was becoming clear that these non-vitamin plant antioxidants have an impact on the antioxidant status of the body that is much beyond their representation in the blood and tissues. For instance, at the conference it was explained that an extract from grape seeds given to human volunteers led to a much greater increase in the antioxidant capacity of the subjects’ blood than was theoretically possible based on the compound alone. This was a finding that called for explanation. A second set of tests helped to clarify the result of the first––the same grape seed extract demonstrated significant synergism when tested in vitro with the antioxidant vitamins C and E, either alone or in combination.

To establish a quantitative baseline for the antioxidant power of each of the compounds, tests used the standard cupric ion generation of oxidation to look at the impact of combining our grape seed extract (Vixox Gold™) with vitamins C and E to gauge the synergy of the combinations. Vitamin C, vitamin E and grape seed extract were each tested individually to determine their effects at several concentrations. These baselines were added to yield the “Sum of Individual Inhibitions” which then was compared with the “Actual Inhibitions When Tested Together.” The Actual Inhibitions minus the Sum of Individual Inhibitions times 100 yielded the percent of Synergism. This series of in vitro tests thus allowed the investigator to elegantly demonstrate the concentrations of maximal synergism amongst the three antioxidants. Strong synergism was shown for Vinox Gold™ plus vitamin C, for Vinox Gold™ plus vitamin E, and, finally, for Vinox Gold™ plus vitamin C and vitamin E.

Synergisms in the ranges shown above are good examples of why it is that consuming a diet rich in fruit and vegetables is so much more successful in terms of health than eating a diet based on refined carbohydrates, protein and fats. Refining the “big three” macronutrients and then “adding back” nutrients/ micronutrients loses the benefits of the plant compounds that otherwise are present in the original sources of carbohydrates and in partially refined oils, such as olive and sesame oils. The antioxidant vitamins are important, but they commonly provide their full potential benefits only when combined with various plant factors.

Synergism is important, yet there are other arguably much more important factors that cannot be reduced to the concept of synergism. In another paper presented at the American Chemical Society National Meeting, Chithan Kandaswami of the State University of New York at Buffalo indicated that grape seed extract acts in ways other than as an antioxidant. The flavonoids found in grape seed along with chemically similar compounds found in other plants act to reduce the signals received by certain cell receptors involved in inflammation and tumor growth and to activate additional signals. Antioxidants commonly are found to help to reduce inflammation, but in this case the protective effect is different from an antioxidant benefit. When researchers attempt to elucidate mechanisms of action, compounds found in foods and herbs often exhibit signaling roles in the body with difficult to define effects and unknown active pathways.

To illustrate this, let’s take a simple example with implications that upend many supposedly established conclusions and vast amounts of research into the relation between nutrition and cardiovascular disease. Saturated fats, such as butterfat, long have been damned based mostly on marker studies as being atherogenic because such fats raise plasma total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C). In 2015, it has become apparent that recommendations against saturated fats that have been in place since 1977 never had conclusive support from randomized controlled trials and that there is a case to be made that total cholesterol and, to some extent, even LDL-C, within a wide range actually are inversely related to total mortality! 1,2,3,4,5 This means that longevity studies based on endpoints (did the subjects live longer or not) routinely have found that in old age higher, not lower, levels of total and even LDL-C within a certain range are associated with better health and longer life. The reader may well ask, “How can so much have been wrong for so long?” One answer is that models based on interventions with pure substances often leave out actual dietary practices and suggest that foods which, in fact, are healthful instead are detrimental to health. Case in point, butterfat.

In 1993, one of the most important researchers exploring the health effects of fats in the diet, FA Kummerow, published an animal study using a model (swine) that is an almost perfect stand-in for humans in terms of lipids and cardiovascular disease to test the effects of consumption of margarine and butter on plasma lipids levels as different amounts of magnesium were consumed. The findings were telling regarding nutrient interactions. From the abstract:

Plasma lipids obtained from swine which had been fed butter or margarine at two dietary magnesium (Mg) levels indicated that the level of dietary Mg was more significant to plasma total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) levels than was the presence of butter or margarine [i.e., omega-6 polyunsaturated fatty acids].…

    Studies in which the influences of dietary fats on plasma cholesterol were first noted were carried out on liquid diets deficient in Mg. Mg, a cofactor in the enzymes involved in desaturation of saturated fatty acids, is also necessary in desaturation of linoleic to arachidonic acid.
6 [Emphasis added.]

In other words, simply adding magnesium to the diet dramatically changed the effect of saturated fat on plasma lipids levels compared to polyunsaturated fat. Interestingly, butterfat, such as is found in full fat dairy, actually protects against diabetes and perhaps other components of the metabolic syndrome.7 The addition of magnesium in this example is not a form of synergy in the usual sense defined above. Instead, it is an instance of how in the diet the entourage effect often plays out.

Many herbalists long have held that in some cases plants yield better results than the natural products isolated from them, a type of “herbal synergism.” However, synergy in the simple sense introduced above involves the total of a particular benefit or effect being greater than the sum of its parts. This is illustrated by the example of delivering together blends of antioxidants whose antioxidant effects, through whatever combination of mechanisms, exceed the sum of their individual capacities as antioxidants. But what do we call the concept if one or more of the components exert no antioxidant effects of their own, may otherwise seemingly even be inert, yet magnify the outcome, reduce side effects and introduce new and unexpected benefits?

Increasingly in the scientific literature, this is called the entourage effect.8 Not surprisingly, the concept emerged with regard to herbs rather than standard pharmaceuticals because it does not lend itself readily to standard testing methodologies which depend upon “one cause, one effect” reasoning and testing. Nevertheless, examples of the entourage effect continuously are in evidence.

A good illustration of the superiority of a complex herbal extract versus “guaranteed potency” based on the ever greater purification of a single ingredient is Ma huang, a plant source of natural ephedra. Starting in the early 1990s and continuing for more than a dozen years, the combination of ephedra and caffeine was popular as a dieting aid because the mixture worked. Despite this fact, ephedra and its sources were banned due to fears of increased hypertension in vulnerable individuals. In the marketplace, relatively high dose extracts from plant sources were not economic beyond concentrations of six percent of the active alkaloid and this led to the widespread use of synthetic sources. Curiously, seriously elevated blood pressure was not normal with the plant source at reasonable levels of intake whereas elevated blood pressure was fairly typical with the synthetic. Why the difference? The answer lay with the entourage effect—in Ma huang there are a number of compounds that lower blood pressure and otherwise modulate the pressor effect of ephedra thus making the plant source far safer than the synthetic pharmaceutical source of ephedra.

Similar cases are found throughout herbalism. The important compound adenosine cannot be successfully supplemented in pure form by mouth, yet is bioavailable as a component of bears’/wild garlic.9 Likewise, the phytosterols beta-sitosterol and its glucoside in combination show significantly greater efficacy than the individual sterols at the same concentration, which is to say beta-sitosterol requires the presence of its typical form found in plants in order to be maximally active.10

A great current example of the entourage effect is cannabis in both its medical and recreational uses. Different strains of the plant that otherwise are analyzed as possessing essentially identical amounts of the “active” ingredients are reported by many or even most users as leading to quite different experiences. The reason is that the plant is the source of 60 or more cannabinoids alone, not just the famous THC and CBD, along with a host of non-cannabinoid compounds, such as terpenes. These differing combinations of compounds can activate or block binding to brain receptor sites and produce a variety of other regulatory effects.

These findings have wide-ranging implications, such as for the use of medical marijuana for cancer. For instance, cannabinoids typically have been used in experimental treatments just like other drugs to block one or another pathway or receptor site based on the genetic mutation theory of tumor development and growth. However, that model, which is the basis of most chemo- and related therapies, recently has taken quite a few hard nocks as it has become increasing apparent that cancers, like other cells and tissues in the body, depend upon epigenetics as much as or more than genetics.11,12

Epigenetics, according to one definition, refers to external modifications to DNA that turn genes “on” or “off.” These modifications do not change the DNA sequence, but instead, they affect how cells “read” genes.13

In epigenetic models of disease, targeting multiple pathways and influencing indirect as well as direct mechanisms is more effective than focusing on a single point.


The entourage effect as a concept very recently has been harnessed by scientists at Harvard and several Central European universities to cover ways of visualizing the relationships between biological pathways.14An argument can be made a number of sophisticated traditional medical systems, such as those of the Tibetans and the Chinese, long have employed this type of modeling. Indeed, neither of these systems nor the related Indian Ayurvedic system traditionally used single herbs in treatments. As one recent compendium describes the principles of Traditional Chinese Medicine:

Chinese herbs are not used singly in treatment, but in combinations known as herbal formulas….Since a [sic] herbal combination has obvious advantages in treatment, the relationships between the herbs used in traditional Chinese medicine (TCM) have been carefully studied and certain types of relationship are identified. They are called the seven relations between herbs, e.g. mutual accentuation, mutual enhancement, mutual counteraction, mutual suppression, mutual antagonism, mutual incompatibility and single effect. Some of these are very useful in treatment, but some are harmful and therefore must be avoided.15

There are other ways of describing principles of formulation, such as major ingredients, directing ingredients, various modifying ingredients, etc., but the ideas are similar.

To illustrate these points, we can return to a Chinese formula that has been mentioned before in these pages, the fermented herb mixture known as Tai Li Wang. Also referred to as a mulberry and sea-buckthorn beverage concentrate to reflect its two most prominent ingredients, Tai Li Wang is suggested for individuals under stress, including mental and physical stress, those recovering from surgery or illness, requiring a large nutritional boost, individuals suffering gastrointestinal problems, and those looking for an anti-aging tonic. Other ingredients include black sesame, black plum, goji, Buddha’s hand, Chinese white olive, fu ling, chrysanthemum and jujube. Fermentation creates further complex components not found in the original herbs. The herbal tradition maintains that Tai Li Wang improves energy, supports the liver and kidney functions, increases blood components and supports their roles, is detoxifying, improves digestion and digestive functions (including being useful in both constipation and diarrhea), and is calming, including aiding sleep. In short, the formula is strengthening and balancing to the metabolism.

These effects refer to the entire formula and the components individually are generally mild in action. However, even mild herbs have limits. Take, for instance, Buddha’s hand. This is a mild herb related to citron that calms the liver and regulates certain types of energy. It is not used by itself if the physiologic system has been depleted due to diarrhea. Similarly, chrysanthemum typically is mild with the properties of cooling and calming, yet it should be used in moderation by those who have a weak digestive system or have diarrhea. The other herbs in the formula balance these constraints and in practice Tai Li Wang serves to normalize bowel function just as it serves to support immune function without causing inflammation and it promotes greater energy without being overly stimulating or depleting as is caffeine. In general, Tai Li Wang is a complex mixture of herbs consumed at really quite low levels as individual components, meaning that its benefits cannot be explained by the quantity of any one component, yet taken together these ingredients magnify the outcome, reduce side effects and introduce new and unexpected benefits.

As noted above, herbalists long have held that in some cases plants yield better results than the natural products isolated from them, a type of “herbal synergism.” One of the dangers of the modern “guaranteed potency herbs” and similar approaches to supplements is that the “guaranteed potency” that originally was meant to insure that the whole extraction was done properly has been deformed to reproduce the pharmaceutical model of pure substances and, as one consequence, leaving out important compounds found in the herbs and in the extracts as originally produced. Single compound and herbs can be combined for synergistic effects, to be sure, but it is easy to lose sight of the benefits, sometimes not at all minor, of the other compounds present in the herbs that may not constitute the active ingredients per se, yet are important for determining how the so-called active ingredients affect the body. This is the entourage effect. It is important in evaluating individual herbs and their extracts. Properly understood, it also can be understood as an organizing principle for a number of traditional medical systems, such as those of the Tibetans and the Chinese.


  1. Harcombe Z, Baker JS, Cooper SM, Davies B, Sculthorpe N, DiNicolantonio JJ, Grace F. Evidence from randomised controlled trials did not support the introduction of dietary fat guidelines in 1977 and 1983: a systematic review and meta-analysis. Open Heart. 2015 Jan 29;2(1):e000196.
  2. Hamazaki T, Okuyama H, Ogushi Y, Hama R. Towards a Paradigm Shift in Cholesterol Treatment. A Re-examination of the Cholesterol Issue in Japan. Ann Nutr Metab. 2015;66 Suppl 4:1-116. doi: 10.1159/000381654.
  3. Ericson U, Hellstrand S, Brunkwall L, Schulz CA, Sonestedt E, Wallström P, Gullberg B, Wirfält E, Orho-Melander M. Food sources of fat may clarify the inconsistent role of dietary fat intake for incidence of type 2 diabetes. Am J Clin Nutr. 2015 May;101(5):1065–80.
  4. de Souza RJ, Mente A, Maroleanu A, Cozma AI, Ha V, Kishibe T, Uleryk E, Budylowski P, Schünemann H, Beyene J, Anand SS. Intake of saturated and trans unsaturated fatty acids and risk of all cause mortality, cardiovascular disease, and type 2 diabetes: systematic review and meta-analysis of observational studies. BMJ. 2015 Aug 11;351:h3978.
  5. Morowitz HJ. Hiding in the Hammond Report. Hospital Practice 1975 Aug:35,39.
  6. Kummerow FA, Wasowicz E, Smith T, Yoss NL, Thiel J. Plasma lipid physical properties in swine fed margarine or butter in relation to dietary magnesium intake. J Am Coll Nutr. 1993 Apr;12(2):125–32.
  7. Op cit. note 3.
  8. Russo EB. Taming THC: potential cannabis synergy and phytocannabinoidterpenoid entourage effects. Br J Pharmacol. 2011 Aug;163(7):1344–64.
  9. Preuss HG, Clouatre D, Mohamadi A, Jarrell ST. Wild garlic has a greater effect than regular garlic on blood pressure and blood chemistries of rats. Int Urol Nephrol. 2001;32(4):525–30.
  10. Bouic PJ, Etsebeth S, Liebenberg RW, Albrecht CF, Pegel K, Van Jaarsveld PP. beta-Sitosterol and beta-sitosterol glucoside stimulate human peripheral blood lymphocyte proliferation: implications for their use as an immunomodulatory vitamin combination. Int J Immunopharmacol. 1996 Dec;18(12):693–700.
  11. Rozhok AI, DeGregori J. Toward an evolutionary model of cancer: Considering the mechanisms that govern the fate of somatic mutations. Proc Natl Acad Sci USA. 2015 Jul 21;112(29):8914–21.
  12. Epigenetics: A New Frontier in Cancer Research. AICR ScienceNow, Volume 20, Spring 2007 at
  14. Lex A, Partl C, Kalkofen D, Streit M, Gratzl S, Wassermann AM, Schmalstieg D, Pfister H. Entourage: visualizing relationships between biological pathways using contextual subsets. IEEE Trans Vis Comput Graph. 2013 Dec;19(12):2536–45.
  15. Yifan Yang. “Theories and concepts in the composition of Chinese herbal formulas” in Chinese Herbal Formulas: Treatment Principles and Composition Strategies. (Edinburgh and New York: Churchill Livingstone Elsevier, 2010.)

Dallas Clouatre, PhD

Dallas Clouatre, Ph.D. earned his A.B. from Stanford and his Ph.D. from the University of California at Berkeley. A Fellow of the American College of Nutrition, he is a prominent industry consultant in the US, Europe, and Asia, and is a sought-after speaker and spokesperson. He is the author of numerous books. Recent publications include "Tocotrienols in Vitamin E: Hype or Science?" and "Vitamin E – Natural vs. Synthetic" in Tocotrienols: Vitamin E Beyond Tocopherols (2008), "Grape Seed Extract" in the Encyclopedia Of Dietary Supplements (2005), "Kava Kava: Examining New Reports of Toxicity" in Toxicology Letters (2004) and Anti-Fat Nutrients (4th edition).