In midst of the low-carb diet craze, pasta has been labeled for being unhealthy and fattening. A recent article published in Nutrition & Diabetes has reported new findings that are different from the public’s perception.
Investigators found that pasta, as part of the Mediterranean diet, was negatively associated with body mass index (BMI) and waist-to-hip ratio (both β-coef<0, P<0.05). This finding was based on the epidemiological data of over 23,000 Italian adults recruited from two studies: Moli-sani and INHES (Italian Nutrition & Health Survey) and tracked for over four years.1
The Moli-sani cohort involved 14,402 people aged 35 or older, who lived in the Molise region in Italy, and the INHES cohort consisted of 8,964 people aged 18 or older from all over the country. Information of dietary intake was mainly obtained by self report, questionnaires and telephone-based interviews. Physical measurements (weight, height, waist and hip circumference) were directly measured by researchers in Moli-sani but self-reported in INHES. Data from the two studies were separately analyzed by the Department of Epidemiology, I.R.C.C.S. Neuromed in Pozzilli, Italy.1
While many studies already demonstrated the health benefits of Mediterranean diet in the management of body weight2-4 and prevention of chronic diseases5,6, very few studies investigated the specific role of pasta as a single food component. Data from this observational study now fills this gap.
The study also reported that pasta eaters tended to consume more foods associated with the Mediterranean diet such as cooked tomatoes and other sauces (women: Spearman’s rho=0.68 and 0.64, P<0.001; men: Spearman’s rho=0.71 and 0.59, P<0.001). Interestingly, the negative association of pasta intake with BMI was independent from the Mediterranean diet adherence. 1
“In popular views, pasta is often considered not adequate when you want to lose weight. And some people completely ban it from their meals. In light of this research, we can say that this is not a correct attitude”, said Licia Iacoviello, Head of the Laboratory of Molecular and Nutritional Epidemiology at Neuromed Institute, corresponding author of the article. “The message emerging from this study, as from other scientific analyses conducted in the context of the Moli-sani project and INHES, is that Mediterranean diet, consumed in moderation and respecting the variety of all its elements (pasta in the first place), is good for your health,” she concluded.7
Scientists generally find the study results provocative, but are hesitant about drawing conclusions from single food studies.
Reshmi Srinath, MD, Assistant Professor of Endocrinology, Diabetes and Bone Disease, Icahn School of Medicine, USA, found that the study results were intriguing because “pasta is a food we usually suggest to our patients to limit due to concern about excessive carbohydrates causing weight gain. Results suggested that the intake of pasta was associated with lower body mass index, and less presence of obesity. This affirms the benefits of the Mediterranean type diet which focuses on whole grains, lean meats, fish, and olive oil.” However, he added “It is important to keep in mind that Italian population may be different from the U.S. population and their overall diet, calorie intake, portion sizes, activity levels may be different.”8
Samantha Heller, MS, RD, CDN, registered dietitian, NYU’s Center for Musculoskeletal Care & Sports Performance Center, USA, agrees with Dr. Srinath that there are difficulties to extrapolate results generated from Italian population to other parts of the world due to cultural difference.
“Mediterranean diet is a lifestyle not a diet per se, it varies depending on the culture in which it is followed,” she said, and added that “Assessing dietary patterns and their relationship to health and disease is more meaningful than singling out nutrients or foods.”8
Meanwhile, there are also question raised about the plausibility of attributing health benefits observed in this study solely to a single food item.
“This study really can’t isolate a single food. In fact, no dietary study can although metabolic ward interventions can get pretty close”, commented David L. Katz, MD, MPH, Founding Director, Yale University’s Yale-Griffin Prevention Research Center. “Inevitably, eating more of “x” as a percent of calories means eating less of “y”; any one food change reverberates through the diet, ” he said, and thinks “more plausible is that the benefits are from an overall dietary pattern, for which routine pasta intake just serves as a marker.”8
Some health care professionals have shown their concerns that the study results were being misinterpreted and distorted by the press, making the public believed that “pasta is a magic bullet for weight loss.”8
Sharon Movsas, RD, CDE, from Montefiore Clinical Diabetes Center, USA, commented “Diet studies are fraught with problems and it would be a mistake to use the results from this study as proof that pasta can benefit weight. These were epidemiological studies that showed a statistical association between pasta intake and lower weight in a specific population. They did not show that pasta was the cause of lower weight. Even with statistical manipulation, it may have been something other than pasta that was responsible for the weight benefit. In addition, information on food intake was mostly obtained through self-report. In the two studies reported in this article, the findings were based on the information provided by participants through phone interviews and questionnaires. It is well known that people, understandably, under report food intake. In this paper, one of the studies even used self-reported weights.”8
Indeed, strong reliant on self-reported data is one major limitation in this study, and the authors have also acknowledged that in the article.
“Limitations are evident also for INHES study. The one 24-h dietary recall could not be considered as representative of the dietary habits of an individual. The telephone-based interviews are under the limitation of misreporting or under/over-estimation of food consumption. The body weight and height was self-reported and under the related bias” they wrote. “Bias of over-estimation or under-estimation presented generally in dietary data was evident also in the present datasets especially in women.”1
To overcome this limitation, the investigators corrected food group consumption by total caloric intake using the ‘energy residual methodology’ which they claimed to be a relatively frequent procedure in the dietary analysis.
As a result, pasta intake expressed as grams per day, originally “seemed to be positively associated with BMI in crude analysis” have “became negative”, they wrote.1
Gunter Kuhnle, Associate Professor in Nutrition and Health, University of Reading, UK, said “The method used by the authors to measure diet is commonly used in many observational studies and relies mainly on self-reporting. This is of course always limited because it requires participants to remember their diet and report it accurately. However, this method has been used successfully for many years and there are methods to address limitations to some extent.”9 But he gives no comments on the statistical manipulation.
“What is interesting, however, is that these results clearly showed that it is wrong to demonise carbohydrates as the data clearly showed that the consumption of food rich in carbohydrate such as pasta does not necessarily have an adverse effect on body weight. The results of this study confirm the current dietary recommendations and support the recommendation for a balanced diet,” he said.9
Taken together, weight loss and its related health benefits should be attained through lifestyle changes, which include a balanced, healthy dietary pattern, rather than believing a single food is the answer.
1. Pounis G, Castelnuovo AD, Costanzo S, et al. Association of pasta consumption with body mass index and waist-to-hip ratio: results from Moli-sani and INHES studies. Nutrition & diabetes 2016;6:e218.
2. Esposito K, Kastorini CM, Panagiotakos DB, Giugliano D. Mediterranean diet and weight loss: meta-analysis of randomized controlled trials. Metabolic syndrome and related disorders 2011;9:1-12.
3. Sacks FM, Bray GA, Carey VJ, et al. Comparison of weight-loss diets with different compositions of fat, protein, and carbohydrates. The New England journal of medicine 2009;360:859-873.
4. Shai I, Schwarzfuchs D, Henkin Y, et al. Weight loss with a low-carbohydrate, Mediterranean, or low-fat diet. The New England journal of medicine 2008;359:229-241.
5. Sofi F, Cesari F, Abbate R, Gensini GF, Casini A. Adherence to Mediterranean diet and health status: meta-analysis. BMJ (Clinical research ed) 2008;337:a1344.
6. de Lorgeril M, Salen P, Martin JL, Monjaud I, Delaye J, Mamelle N. Mediterranean diet, traditional risk factors, and the rate of cardiovascular complications after myocardial infarction: final report of the Lyon Diet Heart Study. Circulation 1999;99:779-785.
7. Pasta isn’t fattening, and can actually help you lose weight, study finds. Science Alert, 2016. (Accessed 13 October, 2016, at http://www.sciencealert.com/pasta-isn-t-fattening-and-can-actually-help-you-lose-wait-study-finds.)
8. Friday Feedback: Pasta, the New Kale? Study suggests carbs aren’t the devil after all. Medpage Today, 2016. (Accessed 13 October, 2016, at http://www.medpagetoday.com/primarycare/dietnutrition/58971.)
9. expert reaction to study reporting that pasta consumption is associated with lower BMI. Science Media Center, 2016. (Accessed 13 October, 2016, at http://www.sciencemediacentre.org/expert-reaction-to-study-reporting-that-pasta-consumption-is-associated-with-lower-bmi/.)