Is soy healthy, or not because of the phytoestrogens?
Soy is probably harmless and possibly beneficial for most healthy adults, but caution is advised for children with thyroid problems. Anyone who eats a lot of soy and has doubts is best off discussing this briefly with a doctor or dietitian.
Soy contains isoflavones, compounds that resemble the female hormone oestrogen but act much more weakly. Whether they turn out to be beneficial or harmful depends on the amount, your age, sex and health status. That makes a simple yes-or-no answer impossible.
For adult women during and after menopause, the evidence for benefit is strongest. A daily intake of 60 mg of active isoflavones appears to modestly reduce hot flushes and other menopausal symptoms, although this effect develops slowly. At 60 to 100 mg per day for at least 6 to 12 months, bone density may increase slightly, which is relevant for the prevention of osteoporosis. At the same time, there are indications that an intake of 40 to 60 mg per day, combined with around 25 grams of soy protein, lowers the risk of cardiovascular disease. For all three findings, these are preliminary results without a clear picture of long-term effects.
Concerns about cancer are understandable, but are not confirmed by the available research. Large population studies even point to a possible reduction in the risk of breast, colorectal and prostate cancer in people who eat a lot of soy. There is no indication that soy fuels hormone-sensitive cancers. These are associations, not proven causes.
In men, fears about reduced fertility and hormonal disruption have been studied at doses of 40 to 70 mg per day. Those studies found hardly any effect on sex hormones or sperm quality. The concern appears to be unfounded for now, but the evidence is limited.
There are two vulnerable groups where caution is warranted. In children who already have an underactive thyroid, isoflavones may further disrupt thyroid function. And in children in general, hormonal changes have been reported with soy exposure, although the significance of these is not yet clear. Soy-based infant formula and high soy snack consumption in young children therefore deserve extra attention, and consulting a doctor or dietitian is advisable in those cases.
This answer is based on multiple review studies of existing research. The findings on menopausal symptoms and cardiovascular risk rest on a reasonable body of human studies; those on bone density, cancer risk and children on fewer and sometimes conflicting studies. Long-term data are largely absent.
Is coffee healthy or unhealthy?
For most healthy adults, three to four cups of filter coffee per day, without sugar and cream, does more good than harm. Pregnant women are a clear exception: limit intake and discuss it with your doctor.
Is fibermaxxing (eating as much fibre as possible) healthy?
Eating more fibre is well supported as healthy for most people, but overdoing it causes gastrointestinal complaints and no additional benefit has been demonstrated. Aim for 25 to 29 grams per day through regular food intake.
Is eating organic food really healthier?
Eating organic probably does not give you better nutritional value, but it does lower your exposure to pesticide residues and to antibiotic-resistant bacteria via meat. For pregnant women and young children, that is the most concrete and well-supported argument.
Are smoothies and fresh juice just as healthy as whole fruit?
Whole fruit comes out ahead of fruit juice: more fibre, greater satiety, and fewer free sugars. Smoothies fall somewhere in between, but are not equivalent to whole fruit either.
Are seed oils like sunflower oil bad for you?
Seed oils like sunflower oil are probably not outright harmful, but cannot be given an unconditional clean bill of health either: ideally, also make sure your diet includes enough omega-3-rich foods such as oily fish or flaxseed to keep the ratio in balance.
Is matcha healthier than regular green tea?
Matcha probably delivers more active compounds than regular green tea, but whether that translates into measurable health benefits in practice depends strongly on the product you buy and what you are using it for.