Decades of nutrition research that highlights the benefits of dietary nutrition and supplement interventions for health have been dismissed by a study published in Annals of Internal Medicine. This is according to Steve Mister, President & CEO at the Council for Responsible Nutrition (CRN). Mister has hit back at the recent umbrella review which reports that few nutritional supplements or dietary interventions offer protection against cardiovascular disease (CVD) or death and that some may cause harm.
Other industry experts have largely rejected the reviews’ negative findings on dietary interventions – such as following the Mediterranean Diet and the Low-Sodium Diet for heart health. The conclusions that supplements do not reduce cardiovascular or all-cause mortality risk, are, however, less refuted. Experts highlight previous research that questions the efficacy of popular supplements such as multivitamins and minerals (MVM).
“Perhaps this review reassures us that despite public concern about diet, we appear to derive sufficient cardiovascular benefit from our current diet that can’t be further enhanced by supplementation. However, MVM supplements provide a wide spectrum of nutrients, and we know from the UK National Diet and Nutrition Survey (NDNS) data that some people are borderline deficient in some of these, such as iodine, selenium and vitamin D,” says Catherine Collins, UK NHS Dietitian.
The study included nine systematic reviews and four new randomized controlled trials (RCTs) that together encompassed a total of 277 trials, 24 interventions and nearly one million participants.
MVMs, antioxidants and fish oil were among the supplements identified, with the West Virginia University researchers concluding that the majority made no difference to mortality or CVD risk. Dietary interventions, including reduced fat intake, also reportedly had no significant effect.
However, they did identify that reduced salt intake, omega 3 LC-PUFA use, as well as folate supplementation was found to reduce risk for some cardiovascular outcomes in adults. Furthermore, combined calcium plus vitamin D use may even increase risk for stroke, note the researchers.
The lukewarm findings have prompted some harsh criticism from industry, especially in regards to the conclusions of the review on dietary interventions.
“This review confirms the vast majority of previous research that has failed to find benefits of most nutritional supplements. But the suggestion that dietary interventions have no benefit does not reflect the totality of the evidence,” says Professor Susan Jebb, Professor of Diet and Population Health, University of Oxford.
While Mister of CRN notes that “this study is a coordinated, all-out assault on nutrition, and the critical role it plays in maintaining health and reducing the risk of chronic disease. Along with a companion editorial and video, this attack recklessly disregards decades of comprehensive carefully developed and well-conducted nutrition research on the benefits of both supplemental nutrients and healthy dietary patterns.”
“The study maligns not only dietary supplements, but also well-established dietary patterns, such as the Mediterranean Diet and the Low-Sodium Diet. The three pieces lack insight from any nutrition-based medical professional or expert with knowledge or appreciation of nutrition research. The study is a Systematic Review of past RCTs and meta-analyses of RCTs with absolutely no observational studies included,” he explains.
Following tried-and-tested dietary patterns has long been hailed as a method that delivers high efficacy in boosting health, particularly in terms of CVD.
A Harvard T.H. Chan School of Public Health and Purdue University found that replacing red meat with healthy plant proteins may be a running start to slashing the risk factors for CVD. A study from January found that a dairy-enhanced Mediterranean Diet will significantly increase health outcomes for those at risk of CVD, even proving more effective than a low-fat diet.
The Mediterranean diet has been particularly revered. A study from January found that a dairy-enhanced Mediterranean Diet will significantly increase health outcomes for those at risk of CVD, even proving more effective than a low-fat diet. Meanwhile, an Italian study identified that senior people, aged 65 years and older, who adhere closely to the Mediterranean Diet have a 25 percent lower risk of any cause of death.
Indeed, Dr. Duane Mellor of the British Dietetic Association (BDA) and Aston Medical School, tells NutritionInsight that, if anything, consumers should take from this study that there is no “one fix for your diet that a supplement can solve.” Additionally, the nutrition industry should “look at how supplements are positioned so that they are clearly seen by consumers as complementary to a diet.” Ideally, whole dietary patterns should be encouraged first, which may even reduce the need for supplements.”
Jebb concludes that two important issues need to be borne in mind in considering the results. Firstly, she notes that any review is only as good as the quality of the underpinning primary research and the authors note the “sub-optimal” quality of the evidence in this study. Second, with so many published analyses about diet and cardiovascular disease, there is a great deal of chance for any review to end up with a biased outcome.
This is not the first study that has questioned the health benefits that may come with supplements.
In April, a Tufts University study noted that an adequate intake of certain nutrients is associated with a reduction in all-cause mortality when the nutrient source is food, but not supplements. It also said that there was no association between dietary supplement use and a lower risk of death.
The Tuft University findings also supported previous studies that discovered that common supplements may offer no consistent health benefits, further emphasizing that a healthy diet is a preferred method for nutrient intake.