Millised On Sojaubade Kõrvaltoimed?

2024 Autor: Cecilia Ryder | [email protected]. Viimati modifitseeritud: 2023-12-17 14:20

Sojauba on laialt tarbitud kaunviljad. See on Aasia dieedi põhitoode ja seda kasutatakse mitme töödeldud toidu koostisosana. Sojas sisalduv valk (sojavalk) võib asendada teie toidus olevad loomsed valgud ja see saadakse pärast sojaubade ja nende rasvhapete väliskesta eemaldamist (1), (2).

Kuigi sojaubades on palju toitaineid nagu kaltsium, raud, tsink ja aminohapped, võivad need põhjustada teatud kõrvaltoimeid (3).

Liigsel tarbimisel võivad need häirida kilpnääret reguleerivaid ravimeid ja põhjustada testosterooni tasakaaluhäireid, allergiaid ja vähi vohamist.

Samuti võib sojatooteid pikemas perspektiivis ülemäärane kasutamine olla ohtlik. Selles postituses käsitleme sojaube ja nende võimalikke kahjulikke mõjusid. Jätka lugemist.

Sisukord

• Mis on sojaubade peamine probleem?
• Mis juhtub sojaube tarbides? Mis põhjustab kahjulikke mõjusid?
• Millised on sojaubade (sojavalgu) kahjulikud mõjud?
• Milliseid sojatooteid peaksite vältima?
• Kui palju on soja päevas ohutu süüa?
• Kas liiga palju soja söömine on kahjulik?

Mis on sojaubade peamine probleem?

Sojaubade peamine probleem on selle isoflavooni sisaldus.

Sojaoad on fütoöstrogeenide (isoflavoonide) reservuaarid, mis on struktuurselt ja funktsionaalselt sarnased teie keha östrogeenhormooniga (3). Isoflavoonid on fütoöstrogeenide klass (neid nimetatakse ka sojavalkudeks), mida leidub sojas ja sojaproduktides. Järgmine tabel peaks andma teile aimu isoflavooni sisaldusest erinevates sojatoitudes.

Kääritamata sojatoidud	Isoflavooni sisaldus (mg)
sojapiim, 1 tass	6
tofu (oakohupiim), pehme, 3 untsi	20
küpsed, keedetud sojaoad, ½ tassi	55
sojaoad, kuiv röstitud, 1 oz.	40
keedetud edamame, ½ tassi	16
sojajuust, 1oz.	2
sojaburger, 1 küpsetis	5
Kääritatud sojatoidud	Isoflavooni sisaldus (mg)
miso, 3 untsi.	37
natto, 3 untsi.	70
tempeh, keedetud, 3 oz.	30
sojakaste, 1 spl	0,02

Allikas: Harvardi THChani rahvatervise kool

Östrogeenhormooni vaeguse kompenseerimiseks on kasutatud soja fütoöstrogeene. Sojavalk on osa östrogeeni asendusravist, mida antakse menopausi läbivatele naistele (3).

Mõned epidemioloogilised uuringud viitavad sellele, et fütoöstrogeenide tarbimine toiduga võib muude sümptomite hulgas vähendada menopausijärgsete kardiovaskulaarsete haiguste, osteoporoosi ja kuumahoogude esinemissagedust. Kontrastsed andmed on teatatud ka fütoöstrogeenide potentsiaali kohta rinna- ja eesnäärmevähi ennetamisel (3).

Kuid soja eelised on olnud ebaselged. Tegelikult väidavad teatud muud uuringud ka seda, et sojavalk võib põhjustada potentsiaalset kahju (3).

Mis juhtub sojaube tarbides? Mis põhjustab kahjulikke mõjusid?

Kui tarbite sojaube (sojavalku) mis tahes kujul, seonduvad soja isoflavoonid (fütoöstrogeenid) teie keha östrogeeniretseptoritega. Need fütoöstrogeenid konkureerivad loodusliku östrogeeniga retseptoritega seondumiseks. Selle tulemuseks on nõrk östrogeenne või antiöstrogeenne toime. Teisisõnu, soja isoflavoonid võivad muuta teie keha loodusliku östrogeeni vähem efektiivseks (3), (4).

Selline suhtlemine võib põhjustada hormonaalset tasakaalustamatust ja põhjustada tüdrukutel soolisi muutusi. Neil võib olla ka meestel antiandrogeenne toime. Mehed võivad hakata kasvama rindu (günekomastia) ja kogeda oma spermatosoidide kontsentratsiooni, kui nad on sojaga dieedil (3).

Isoflavooni üleannustamine pikema aja jooksul võib naistel stimuleerida endomeetriumi (emakat) ja rindu. Seetõttu soovitatakse kõigil, kellel on rinnavähk ravitud, sojavalku vältida (3).

Fütoöstrogeenid võivad mõjutada mitmeid keha füsioloogilisi ja patoloogilisi protsesse. Suured sojaisolaatide annused võivad avaldada kahjulikku mõju paljunemisele, naha, luude ümberkujundamisele, kardiovaskulaarsüsteemile, närvisüsteemile, immuunsüsteemile ja ainevahetusele.

Vaatame üksikasjalikult sojaubade (sojavalkude) kahjulikke mõjusid.

Millised on sojaubade (sojavalgu) kahjulikud mõjud?

1. Võib segada kilpnäärme regulatsiooni

Sojatoidud võivad suurendada kilpnäärme funktsiooni häirega inimeste hüpotüreoidismi tekke riski. Sellistel inimestel võivad tekkida struuma ja autoimmuunne kilpnäärmehaigus. See risk suureneb veelgi, kui inimese joodi tarbimine on madal (5).

On leitud, et soja isoflavoonid pärsivad kilpnäärme peroksüdaasiks nimetatava ensüümi aktiivsust. See ensüüm on vajalik kilpnäärmehormooni sünteesiks. Sellepärast võib palju sojavalku süües tekkida hüpotüreoidismi oht (6).

Sojatooted häirivad ka kilotüreoidhormooni puudulikkuse raviks kasutatava ravimi levotüroksiini (L-türoksiin) imendumist (7). Kuna sojavalgud näivad muutvat ravimite kättesaadavust, võidakse teil soovitada sojavalgu tarbimist, kui teil on kilpnäärme tasakaaluhäired.

Kuid just sojaisoflavoonide rohke tarbimine ei suurenda kilpnäärme alatalitluse riski, välja arvatud juhul, kui see on seotud toidujoodi ebapiisava tarbimisega. Seetõttu on sojavalgu mõju kilpnäärmele vaieldav. Sellega seoses on vaja rohkem uurida.

2. Võib põhjustada testosterooni tasakaaluhäireid

Uuring viidi läbi 12 meessoost isikul, kes tarbisid neli nädalat 56 g sojavalgu isolaati päevas. Selle tulemusena langes nende testosterooni tase seerumis 19% (8). Kuigi andmed olid vastuolulised, leiti, et sojavalk vähendas tervetel meestel seerumi testosterooni taset.

Väidetavalt on sojavalgul kahjulik mõju meeste reproduktiivsele funktsioonile. Selles osas pole siiski konkreetseid uuringuid. Mõnes loomauuringus on tegelikult öeldud, et sojaisoflavoonid ei avalda meestele feminiseerivat mõju (9).

Most of the observations are based on lab and animal studies. Hence, the relationship between soy isoflavones and testosterone is inconclusive (10).

3. May Elicit Hypersensitivity (Allergy)

Soy products can cause allergies or hypersensitivity in children and adults. Often, soy allergy starts in infancy, with reaction to soy-Soy products that can cause allergies or hypersensitivity in children and adults. Often, soy allergy starts in infancy with a reaction to soy-based infant formula. However, most children outgrow soy allergy (11).

Generally, soy allergy is uncomfortable but not severe. An allergic reaction to soy is rarely frightening or lethal. Symptoms of soy allergy may include tingling in the mouth, eczema or itchy skin, wheezing, diarrhea, stomach ache, vomiting, and skin redness (flushing) (12).

If you experience any of these symptoms, you may have a soy allergy. Get tested to confirm the allergy. If tested positive, you may be advised against having soy products/isoflavones.

4. May Increase The Risk Of Cancer Proliferation

Soy isoflavones (one of them being genistein) may stimulate the proliferation of cancer cells in your body. This is especially true in the case of estrogen-dependent breast cancer, as soy isoflavones tend to have estrogenic effects (13).

As per animal studies, genistein may deregulate the cell cycle and trigger tumor development. It acts by triggering the estrogen receptors (14).

Contrarily, human studies show an inverse relationship between cancer and isoflavones. Soy intake was also found to reduce the incidence and death rate caused due to breast cancer. This could be because of the anti-estrogenic effect exerted by phytoestrogens (13).

The amount and source of soy isoflavones also greatly impact breast cancer risk (14).

5. May Trigger Alzheimer’s Dementia

Traditionally, soy foods were used in cooking only after fermenting. This two-step routine would destroy most of the anti-nutrients in soy, such as isoflavones (like genistein and daidzein) and DNA-altering enzymes (like topoisomerases) (15).

When you eat unfermented, cooked/uncooked soy foods, these anti-nutrients may affect the vital systems of your body, including your brain (15).

These anti-nutrients in soy could have detrimental effects on many individuals. Soy isoflavones could increase the risk of Alzheimer’s dementia (15).

If you are dealing with dementia or have a family history of this condition, it is safe to reduce your soy consumption (15).

6. May Cause Infant Health Issues

Infant food formulas contain fair amounts of soy protein/isoflavones. Infants who are fed these formulas are exposed to 5.7–11.9 mg isoflavones/kg body weight during the first four months of life (16).

These kids are exposed to 6–11 times higher levels of isoflavones than adults. This could lead to disturbances in the reproductive health and endocrine function in the child. The major isoflavones, daidzein and genistein, preferentially bind to the estrogen receptors in the body (16).

However, these conclusions are based on animal studies. Human studies may give a different picture. Moreover, currently available soy-based formulas show no overt toxicities in healthy infants (16), (17). Hence, check with your pediatrician before giving soy-based formulas to your child.

7. Unsure Osteoprotective Effects

Soy protein has shown to conserve bone mineral density, particularly in postmenopausal women. In perimenopausal women, the soy isoflavones were shown to prevent bone loss from the lumbar spine. These compounds had no significant effect (neither positive nor negative) on bone formation and/or bone resorption (18).

In some cases, the mineral balance could be impaired with soy consumption. Soybeans contain (by weight) about 1–3% phytic acid (also called phytate). Phytic acid is an anti-nutrient that binds to minerals like zinc, iron, and calcium. Along with soy isoflavones, phytic acid also may decrease their bioavailability (18).

However, a major chunk of literature highlights the osteoprotective effect of soy protein. Further research is needed to determine the precise impact of soy protein/foods on bone density and other related diseases (19).

Most of the research on soybeans and soy protein is still unclear. While in some studies they seem to promote health, certain other studies tend to state the potential harm they may cause. However, this does not mean you have to totally be off soy. There are a few specific soy products you may want to avoid.

Which Soy Products Should You Avoid?

Moderation is important, and so is eating right. Choosing the right kind of soy products can protect you from the adverse effects mentioned above.

When given a choice between natural soy foods and soy protein isolate, go for the natural options. Avoid industrial soy foods if you have iodine deficiency or thyroid imbalance (15).

Whole soy foods are mostly fermented and cooked in a healthier manner. You can take tofu, edamame, soy milk, tempeh, miso, and natto a few times every week.

How Much Soy Is Safe To Eat In A Day?

According to the US FDA, daily consumption of 25 g of soy seems to be safe. This amount of soy could also help lower cholesterol levels (20).

It also is believed that the intake of 50 g of soy protein per day could help prevent heart disease, diabetes, and estrogen-dependent cancers. However, more research is warranted.

There is limited information on the excess intake of soy protein/soybeans. But we don’t recommend you take more than 25 grams per day.

Is Eating Too Much Soy Harmful?

There is little information about the toxicity of soy protein. In limited doses, soy protein may be helpful for women who are at a high risk of breast cancer (21).

Some studies reported very few drug-related adverse events, which were mild. In very few cases, high levels of soy isoflavones adversely affected blood pressure levels (22).

Hence, it is important you talk to your healthcare provider about a suitable dosage for you.

Conclusion

Soy protein could be the reason Asians have historically had lower rates of cardiovascular disease. Their menopausal symptoms and incidence of breast cancer, diabetes, and obesity are also lower than their Western counterparts (23).

There is substantial yet unclear evidence stating the adverse effects of soybeans and soy protein/foods. Soy isoflavones may disturb the hormonal balance, stimulate cancer proliferation, and trigger allergies.

Hence, choose your soy portions carefully. Pick fermented soy foods over protein or isoflavone isolates. Follow the instructions by your physician/nutritionist and stick to the recommended intake limit.

23 sources

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