Fight against fatigue or protect against cancer, food supplements have many virtues. But when is it exactly? Researchers respond.
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Even unbelievers let themselves be tempted by telling themselves that a little cure can not hurt, at worst, that it will have no effect. Food supplements have more and more followers. As proof, the NutriNet-Santé study, conducted since 2009 and coordinated by Mathilde Touvier (1), shows that 15% of men and 28% of women consume it at least three days a week.
Figures to be compared with those of the nutrivigilance system of the National Agency for Food, Environmental and Occupational Health Safety (ANSES) which recorded 282 reports of adverse effects linked to their consumption last December. . Food supplements are therefore attractive, but not all harmless.
How to navigate
Among the food supplements with proven benefits, it is accepted that folic acid, taken before and during the first trimester of pregnancy, helps prevent spina bifida, a birth defect. Others compensate for the deficit (2) of nutrients (3) due to particular situations.
Thus, “it has been shown that multivitamin supplements are beneficial after digestive tract operations, and that iron and vitamin B12 can be justified for women having particularly heavy periods”, indicates Jacques Fricker (4), nutritionist at Bichat hospital in Paris. Last example: vitamin D, useful in the event of a lack of sunlight, for growing children and the elderly at risk of osteoporosis (5).
Conversely, some can harm the health of some consumers. Vitamins A and E are not recommended for pregnant women because they can cause birth defects in their babies. Another example is vitamin D, which an American study indicates that the risk of invasive breast cancer increased in women by taking more than 600 IU (6); a phenomenon that will be studied among French women as part of the VitaOx study, led by Mathilde Touvier and Marie-Christine Boutron-Ruault (7).
We can also cite food supplements based on phytoestrogens (8), in particular those derived from soy isoflavones, which ANSES advises against to people having, or having had, hormonal-dependent cancer (9), and to patients treated with tamoxifen or lezotrozole, which block the action and production of estrogen, respectively.
Drug interactions
The second problem encountered is the interaction with drugs. Various studies warn about this phenomenon, in particular for St. John’s Wort, qualified as a natural antidepressant, which interacts with twenty families of drugs.
Moreover, these interactions are not without consequences, as evidenced by the reports of adverse effects received by ANSES following the consumption of food supplements based on red yeast rice. In this case, the risk identified is that this product duplicates anti-cholesterol treatments based on statins (10)
Compositions are falsified
The negative effects can also come from too strong doses or from “unfortunate” associations as for p-synephrine which combines the two throughs. This compound, obtained from bitter orange peel, is sold as a slimming supplement. However, last May, ANSES issued an opinion indicating that these products should not exceed a content of 20 mg of p-synephrine, nor contain caffeine “because of their cumulative, or even synergistic, cardiovascular effects,” specifies the agency.
Finally, it happens that the compositions are falsified. “We have just analyzed 150 food supplements for erectile purposes and 130 slimming supplements, indicates Myriam Malet-Martino (11), 61% of the former and half of the latter are non-compliant. If we take this type of product, we therefore have a high probability of also consuming a drug, or a molecule never evaluated in humans, or a prohibited treatment.
Françoise Dupuy Maury
Science et Santé, the Inserm magazine
(1) Mathilde Touvier: unit 1153 Inserm / Cnam / Université Paris 13 / Université Paris 7- Denis-Diderot / Université Paris-Descartes – Center for research in epidemiology
and statistics Sorbonne-Paris Cité
(2) Deficiency: The level of a nutrient in the body that causes suboptimal health.
(3) Nutrient: Food substance which does not need to undergo digestive transformations to be assimilated by the body.
(4) Jacques Fricker: Endocrinology, Diabetology, Nutrition Unit – Bichat-Claude-Bernard Hospital
(5) Osteoporosis: Disease which results in a decrease in bone mass resulting in brittle bones.
(6) IU (or International Unit): Quantity of a nutrient in relation to its biological activity (its effects). Measure set by international agreement and different for each nutrient
(7) Marie-Christine Boutron-Ruault: Inserm unit 1018 / University of Versailles-Saint-Quentin-en-Yvelines – University of Paris Sud 11 Center for research in epidemiology and population health
(8) Phytoestrogen: Estrogen (sex hormone) of plant origin
(9) Hormonal dependent cancers: Cancers of the breast, uterus, ovaries, prostate, testes
(10) Statins: Lipid-lowering molecules used in the prevention of cardiovascular disease
(11) Myriam Malet-Martino: UMR CNRS 5068, University Toulouse III-Paul-Sabatier
Publications
JA Cauley et al. J Womens Health, November 5, 2013; 22 (11): 915-29 doi: 10.1089 / jwh.2013.4270
A. Sparreboom et al. J Clin Oncol, June 15, 2004; 22 (12): 2489-503 doi: 10.1200 / JCO.2004.08.182
V. Gilard et al. J Pharm Biomed Anal, Oct 22, 2014; 102C: 476-93 doi: 10.1016 / j.jpba.2014.10.011