Soy - Consumption to watch - Survey - UFC-Que Choisir
© Clemence MonotConsumption to watch
Published on:23/05/2019 Share on FacebookShare on Twitter>Today, soy is increasingly on our plates. However, it contains molecules active on the hormonal level, the isoflavones, whose harmlessness remains to be proven. Hormonal regulators with beneficial effects for some, potentially dangerous endocrine disruptors for others, these compounds are sparking a lively debate between a food industry with a generally reassuring discourse and researchers worried about their consequences for health. What to Choose takes stock.
YouTube conditions the reading of its videos to the deposit of tracers to better target advertising according to your navigation. By clicking on “Allow” the trackers will be deposited and you will be able to view the video. → Test What to Choose: Comparative Soy-Based PreparationsAperitif seeds, vegetable drinks, tofus… Soy is no longer confined to organic stores and is now flourishing on supermarket shelves. No more soft white squares and tasteless juices! Declined in all sauces, the little seed that rises today seduces a large public anxious to limit their consumption of meat, both for their health and for that of the planet. According to Sojaxa, an association for the promotion of soy foods, 6 out of 10 French people said in 2017 that they had eaten products containing it, an increase of 49% in three years. And a quarter of these buyers, sometimes dubbed "flexitarians", even intend to increase their consumption by 2020.
Because soy has an overall positive image. But if its nutritional assets are very real, the hormonal activity of the isoflavones that it naturally contains cannot be ignored. Pending the definition of an official toxicological reference value (TRV) and in the name of the precautionary principle, its consumption should therefore be limited as much as possible.
On the manufacturers side, we want to be reassuring: the share of soy in the diet of the French would be far from exposing them to worrying doses of isoflavones, molecules that are also unregulated. "In the context of a diversified diet, this intake rarely exceeds one product per day, which generally does not allow the exposure limit set by ANSES (National Food Safety Agency) to be reached in 2005,” says Gwenaëlle Joubrel, scientific advisor to Sojaxa. That is a threshold of 1 mg of isoflavones per kilo of body weight per day (60 mg for a 60 kg adult, for example). An argument taken up by most producers during our discussions. However, there are several limitations to this reasoning.
A range limit value… limited
This threshold value, proposed by ANSES 14 years ago, cannot be considered a toxicological reference value, by the very admission of the Agency, questioned on the subject by Que Choisir: "[Our] latest work on isoflavones date from the 2016 infant Total Diet Study (TDS). […] In this context, the previous maximum limit of 1 mg/kg/day retained for all aglycones, isoflavones and coumestanes (different possible forms of phytoestrogens, editor's note) no longer seemed sufficiently protective. This is why, in the absence of official toxicological values, the exposure limits, which we consider admissible and on which we base our assessment, in particular based on work on recent animal models, are lower than those set by ANSES. in 2005. Thus, in our table, for an adult, a product of which a portion provides at least 33 mg of isoflavones obtains and, for a child, a food providing at least 17 mg of isoflavones receives .
The results of our analyzes on some fifty products are instructive. Thus, 100 g of natural tofu from Céréal bio corresponds to twice the maximum isoflavone intake that we deem acceptable for a child, while a cup (25 cl) of soy juice from the same brand is equivalent to three times the maximum intake for a child and one and a half times for an adult. Finally, Alpro's Nature soya plant-based "yogurt" represents one and a half times the maximum intake for a child and is sufficient to cover 75% of that of an adult.
The consumption of isoflavones can therefore quickly increase, even with a single product per day. But also via preparations containing “hidden” soy, especially among young consumers (see infographic). For example, a portion of Mini Beef Meatballs from Auchan provides 68% of the maximum allowable intake for a child. However, in this product, soy is not highlighted on the packaging. On the contrary, it is a low-cost source of protein integrated into a recipe that relies on the meat it contains.
Finally, there is a large difference in isoflavone concentration between the different families of soy products available on the market. Our test shows that the largest vectors of isoflavones are by far chewable aperitifs: a small sachet (28 to 43 g depending on the brand) provides 52.82 mg to 108.44 mg of isoflavones. We almost double to quadruple the exposure considered critical for an adult! The explanation lies in the production of these toasted seeds: they undergo dehydration concentrating their isoflavone content. Vegetable drinks, more consumed, do not do much better. Indeed, the equivalent of a large glass (25 cl) provides between 7.9 mg and 30.8 mg of isoflavones (i.e., in our table, an evaluation of à for adults and of à for children). Again, their manufacturing process does not filter isoflavones.
Master the manufacturing processes
However, not all soy-based products expose you to a large quantity of isoflavones: this could be limited by controlling the manufacturing process. Work, carried out in particular by Professor Catherine Bennetau-Pelissero, who has studied their traditional production, has shown that solid preparations based on soy, such as tempeh or tofu, were once obtained by long phases of soaking and disposal of the first cooking water. A technique that would reduce the content of isoflavones in soybeans, which diffuse into the water. However, since the 1960s, industrial processes have significantly reduced these steps. "The products designed today contain much more isoflavones than in the past," says the researcher.
But this is not inevitable according to some manufacturers. Like MCÖ Production, which produces catering products based on textured soy proteins in Maine-et-Loire (especially for canteens in the Nantes region) and is working to reduce the isoflavone content. This argument would not leave the agri-food industry unmoved, despite its lack of official enthusiasm for the subject. “We are in advanced discussions with retail groups to sell our products under private label and own brand, explains Gildas Conan, one of the founders of the start-up. They are sensitive to the fact that endocrine disruptors and, by necessity, phytoestrogens are of concern to consumers. But changing their manufacturing processes involves a real cost. They are therefore delighted that we are providing them with a turnkey solution. »
Reducing incidental exposure to these substances is a priority. Unfortunately, it is impossible today for the consumer to know which product to choose to limit it in the absence of labeling indicating the isoflavone content, as ANSES nevertheless recommended in 2005. We bet that manufacturers will have quick to seize the question by ceasing to hide behind their peas… of soya.
Your exposure to isoflavones according to your profile
Soy in all sauces
Soy milk or tonyu: the soybeans are cooked and then ground in the cooking water which is filtered in order to eliminate the grinding debris. White in colour, this juice is consumed as a drink or used to prepare sauces and “dairy” desserts.
Soy yogurt: it is obtained by adding lactic ferments to soy milk.
Tofu: it is made from curdled soy milk using nigari (magnesium chloride). Once drained and pressed, it gives a kind of cheese with a neutral taste, soft (“silky” tofu) or firm.
Soy flakes (or textured soy protein): these are pressed soybeans from which the oil has been extracted. They are then extruded using an endless screw. They are used in particular to increase the protein content of certain recipes at a lower cost (meatballs, minced meat, etc.).
Soy sauce: this spicy sauce is made by fermenting crushed cooked soybeans to which various ingredients such as fermented rice can be added.
Miso: this strong-tasting paste is made from crushed soybeans, mixed with koji, a fermented preparation made from cereals (barley, wheat or rice, etc.), Aspergillus oryzae mushroom and water.
→ Test What to Choose: Comparative Soy-Based PreparationsMarie-Noelle Delaby
Contact the authorCecile Lelasseux
Technical Writer
