Soy isoflavones make up a group of substances with the same structure as the main sex hormones from humans: estrogens.
- 1. What are soy isoflavones?
- 2. Where do soy isoflavones come from?
- 3. Properties of soy isoflavones
- 4. Benefits of soy isoflavones
- 5. How to take soy isoflavones
- 6. Soy isoflavone supplements
- 7. Contraindications of soy isoflavones
- 8. Side effects of soy isoflavones
- 9. Soy isoflavones and evening primrose oil
- 10. Bibliography
- 11. Related Entries:
What are soy isoflavones?
It is one of the treasures hidden in this multifaceted plant. Actually, it has a chemical composition made up by the following active compounds:
Let’s not forget that since it was discovered in China, soy has become one of the most important protein sources for human beings.
This plant is native to Asia. It started to become popular in America during the 19th century. Currently, Brazil and Argentina are the two main producers of this plant.
The two World Wars paralyzed the supply of coconut oil and palm kernel from the East. Consequently, soy became an oleaginous plant.
Where do soy isoflavones come from?
Chemically speaking, isoflavones belong to the crowded group of polyphenols. In fact, said group is made up by more than 6000 substances which are closely connected to the plant kingdom. Therefore, you can find them in different botanical species with varied typologies and origins.
This chemical complex has many uses and benefits for human health. It can have a phytoestrogen capacity, a condition that allows our body to recognize them as molecules equal to female estrogens
Soy isoflavones and estrogens
The main task of estrogens consists of defining the development of the secondary sexual features of women. For instance, the growth of the breasts, the widening of the hips, a higher voice pitch or a lack of hair follicles.
All in all, estrogens are the ones responsible for the physical features of women.
Properties of soy isoflavones
In their natural state, inside the plant tissues, isoflavones lack any biological activity. It is only when we take them from food or food supplements, that the bacteria from our bowel microflora break down their molecules and transform them.
Consequently, we will need a constant supply in order to obtain a sustained from their properties. That is why it is advisable to take two or three servings daily.
Functioning in the organism
Soy isoflavones basically affect the organs and tissues with beta receptors due to their ability to selectively work on the different estrogen receptors (alpha and beta). For instance, the central nervous system (brain and bone marrow), the bones and the arterial walls.
On the one hand, this property adds to the previous one, since they prevent the oxidation of LDL and foam cells. The latter are basically changes of muscle cells from the arterial wall and macrophages that appear with the onset of atheroma plaques. Above all, this antioxidant power projects its benefits on the onset of cancer, which is why it could help with its prevention.
Enzyme inhibition capacity
It is possible to say that isoflavones have an anti-cancer effect, although it could be of residual nature. Said effect could be achieved by blocked three enzymes:
- Tyrosine-kinase: its inhibition is precursor of an analogous effect on the expression of some oncogenes. As well as the disappearance of some specific receptors of cell proliferation factors, such as tumor growth
- Topoisomerase II: isoflavones trigger the death of cancer cells after chemically binding to the DNA-topoisomerase II complex
- Aromatase: by inhibiting this enzyme, the prevent the synthesis of 17-beta-estradiol (an estrogen) from testosterone. Consequently, it blocks the onset of hormone-dependent tumors such as breast cancer
Benefits of soy isoflavones
Improving the absorption of calcium is one of the most relevant properties of soy isoflavones
With the arrival of menopause, women experience two primary phenomena. First, the body stops producing ovules in the ovaries and, therefore, the estrogen synthesis drops considerably as well.
Indirectly, these changes also involve the onset of a series of organic and psychic manifestations with different intensity. For example, fluid retention, intense sweating, hot flushes, dry mucosa, frequent headaches, irritability, emotional instability and sleep problems.
Soy isoflavones play a very important role within this special diet that women follow during this period.
Functioning during the menopause
Supplanting the identity of estrogens can help, for instance, to prevent one of the most worrisome effects of menopause: bone decalcification.
They do so by avoiding the calcium transport from the bone matrix (as essential constituent of hydroxyapatite). At the same time, they ensure the absorption of said mineral, which is another consequence of the estrogen loss.
In general, they help to combat the external symptoms of menopause by compensating for the estrogen loss. Consequently, the use of isoflavones is specially important during the climacteric period. Moreover, women should also increase the intake of calcium and vitamin D.
One of the dangers of menopause is the higher frequency of disorders of this kind.
So, we know that isoflavones keep the LDL levels (“bad cholesterol”) under control as well as the total blood cholesterol. Moreover, they contribute to regulating the triglyceride profile. Consequently, this results in a lower risk of suffering arteriosclerosis.
It is based on an anabolic effect (that is, the “creative” metabolism) on the bone. In fact, it stimulates the proliferation of osteoblasts (responsible for the formation of the bone matrix). At the same time, the protect these cells against the oxidative damaged caused by the free radicals.
Their effect is complete with the stimulation of the DNA and collagen synthesis. In addition, they also hinder the function of the osteoclasts (cells in charge of reabsorbing the bone matrix, the opposite of the osteoblasts).
Synthesis of hyaluronic acid
Soy isoflavones stimulate the synthesis of hyaluronic acid. It is an essential polysaccharide for the texture of the epidermis, whose abundance improves the aspect of the skin. It slows down the deterioration of collagen and elastin, the two structural proteins from the skin tissue. All in all, having more elastic fibers will slow down the onset of wrinkles and expression lines in the skin.
The latter eliminate substances that do not belong in our body. While the former, also known as leukocytes, neutralize invading microorganisms. Moreover, they store the antigen composition on their cell memory in order to be ready to face future threats.
Studies about Alzheimer
There are different research lines open regarding the possibility to prevent Alzheimer’s disease in post-menopausal women. The scientists believe that they could buffer the brain changes associated with this degenerative disorder.
During the menopause, women experience a tendency to accumulate fat. This mainly occurs in two places: in the liver, producing hepatic steatosis (fat accumulation in this organ). And in the adipose tissue, accumulating brown fat, which is used to preserve the temperature.
Regarding this last aspect, the arrival of climacterium is associated with the need of keeping the weight under control. Soy lecithin, one of the products from this plant has a high isoflavone concentration. Therefore, it could provide an important support to prevent this weight gain. It is available both in tablets or capsules.
Benefits for men
Let’s not forget that soy isoflavones can support men as well. How? On the one hand, they lower the risk of suffering prostate cancer and suppress the predisposing factors for heart attacks.
These effects tend to take place during a period known as andropause. During this period, the synthesis of sex hormones leads to certain physiological changes that specially affect the heart and circulatory system.
How to take soy isoflavones
When it comes to planning its consumption through the diet, the difference between soy and the rest of leguminous plant is quite substantial. While 100 grams of soy provide around 300mg of isoflavones, other legumes would need three kilos to reach that number.
In addition, there is also a sensitive contrast between whole soy or sprouts and soy oil and the different varieties of fermented soy. The latter has a much more efficient absorption as well as a stronger effect. Among these varieties, tempeh (soy fermentation from Indonesia) or tamari (authentic soy sauce) are some of its most clear representatives.
Phytoestrogens, which are present in many vegetable products, are divided in different categories: lignans (linseed and whole cereals), soy isoflavones (green tea and red tea), the coumestans from legumes and indoles from cabbage and other cruciferous vegetables. If we had to make a list of products rich in phytoestrogens, we would have to include celery, garlic, cereals (rice, oats, wheat…), legumes (beans, peas…), some fruits (apple, cherry…), some vegetables (carrot, broccoli…) as well as seeds (pumpkin, sesame…).
From other products
At the same time, we can take isoflavones from other products that have been enriched with them. That is the case of milk, juices or enriched yogurts.
When it comes to their intake, it is better to do so during the meals. However, we should bear in mind that a diet rich in fiber will hinder their absorption.
Soy isoflavone supplements
Both the food and nutraceutical industry have started new production lines in order to exploit the potential of these compounds as much as possible. In fact, it is common to find different dietary supplements that have eye-catching mentions about being enriched with isoflavones.
Regardless of the ones we take from the diet, sometimes we will need to take isoflavones from nutraceutical supplements. That is, tablets or capsules with a high concentration of the active ingredients. But always under medical supervision.
Contraindications of soy isoflavones
- Allergies: Isoflavones can trigger allergic reactions in hypersensitive individuals. However, it is probably the most common contraindication.
- Hypothyroidism: they are not advised for those who suffer this disorder and are already following a treatment. This is due to the fact that they can neutralize the effects of the medication. Isoflavones tend to produce an irrelevant loss of iodine. Therefore, it is advisable to combine it with a supplement of this mineral.
- Anti-tumor treatment: Soy isoflavones can interact with the medication against breast cancer. More specifically, they can inhibit the effect of tamoxifen.
- When following a hormone treatment of any kind.
- They can alter the ovary cycle: This problem can worsen if it is simultaneously combined with alcohol.
Side effects of soy isoflavones
Taking soy isoflavones can cause some side effects. Most of them involve gastrointestinal alterations, such as flatulence or diarrhea.
Moreover, they can hinder the absorption of some minerals such as zinc and iron.
Isoflavones can inhibit the tyrosine-kinase enzyme. According to studies on laboratory rats, it could counter the effects of insulin in those tissue that need this hormone.
We cannot discard a chronic effect of resistance against the activity of insulin. Although to this date, there is no proof that isoflavones can cause hyperglycemia in people who suffer diabetes mellitus.
Soy isoflavones and evening primrose oil
Its richness in phytoestrogens has proven that evening primrose oil can support the production of substances similar to sex hormones. Consequently, it is able to control the symptoms of menopause.
Evening primrose seeds are an excellent source of one of the essential fatty acids from the omega-6 series, gamma-linoleic acid (GLA).
A phytotherapy that uses red clover and soy isoflavones is an effective remedy against the symptomatology of menopause. Many studies supports that it can improve the quality of life, particularly that of post-menopausal women.
Regarding menopause, it can considerably reduce the intensity and frequency of the hot flushes and the sweating. In addition, it can regular the blood lipid profile.
- Qiu S, Jiang C. Soy and isoflavones consumption and breast cancer survival and recurrence: a systematic review and meta-analysis. Eur J Nutr. 2018 Oct 31. doi: 10.1007/s00394-018-1853-4.
- Eskra JN, Schlicht MJ, Bosland MC. Lack of combination effects of soy isoflavones and taxane chemotherapy of castration-resistant prostate cancer. Prostate. 2018 Oct 21. doi: 10.1002/pros.23727.
- Tit DM, Bungau S, Iovan C, Nistor Cseppento DC, Endres L, Sava C, Sabau AM, Furau G, Furau C. Effects of the Hormone Replacement Therapy and of Soy Isoflavones on Bone Resorption in Postmenopause. J Clin Med. 2018 Sep 21;7(10). pii: E297. doi: 10.3390/jcm7100297.
- Roozbeh N, Kashef R, Ghazanfarpour M, Kargarfard L, Darvish L, Khadivzadeh T, Dizavandi FR, Afiat M. Overview of the Effect of Herbal Medicines and Isoflavones on the Treatment of Cognitive Function. J Menopausal Med. 2018 Aug;24(2):113-118. doi: 10.6118/jmm.2018.24.2.113. Epub 2018 Aug 31.
- Sathyapalan T, Aye M, Rigby AS, Thatcher NJ, Dargham SR, Kilpatrick ES, Atkin SL. Soy isoflavones improve cardiovascular disease risk markers in women during the early menopause. Nutr Metab Cardiovasc Dis. 2018 Jul;28(7):691-697. doi: 10.1016/j.numecd.2018.03.007. Epub 2018 Apr 10.