Is soy healthy, or is it harmful because of the phytoestrogens?
Ordinary soy foods such as tofu, edamame, and soy milk are safe for most healthy adults and may help a little against hot flashes. High supplemental doses are not recommended for people with hormone-dependent cancers.
Soy contains phytoestrogens, also known as isoflavones. These resemble the female hormone estrogen, but work in a fundamentally different way in the body. A large meta-analysis of 40 studies involving more than 3,200 postmenopausal women shows that soy isoflavones at a typical dose of 75 mg per day have NO measurable hormonal effect on the uterus, hormone levels, or vaginal tissue1. The fear that soy 'acts like a hormone' therefore does not hold up at normal consumption amounts.
For hot flashes and night sweats around menopause, soy isoflavones do help a little. Interestingly, the effect is strongest in women whose gut bacteria produce a compound called equol. Not everyone makes it, and that explains why results can vary so much from person to person2,3. For bone health, findings are mixed: some studies see less bone loss in the spine, others do not. That evidence is not yet solid enough for a firm conclusion.
For cardiovascular disease, several population studies find an association between eating more soy and a lower risk of cardiovascular disease. But that is associative evidence, not proof that soy actually prevents the disease. The same applies to cancer: epidemiological studies suggest a slightly lower risk of breast and prostate cancer in people who eat soy foods regularly throughout their lives4. The mechanisms are not fully understood and the evidence is not definitive.
There are also points to be aware of. In children who already have reduced thyroid function, isoflavones can suppress the thyroid further; in healthy adults, that effect is small or absent5. More importantly, for hormone-dependent cancers, such as certain forms of breast or prostate cancer, high supplemental doses of soy isoflavones are not recommended. Ordinary soy foods, meaning tofu, edamame, or soy milk, are considered safe based on the available evidence. For cognition or urinary tract complaints, there is still too little evidence that soy isoflavones are helpful.
The evidence comes from one large meta-analysis of randomised trials (PMID 39433088, n=3,285), multiple systematic reviews and meta-analyses (PMID 33809928, 40725220, 27886135), and observational research. The thyroid risk is based on limited evidence (PMID 32824177). For cancer risk and bone health, the evidence is limited and partly contradictory.
Is fibre-maxxing (eating as much fibre as possible) healthy?
Eating more fibre is a good idea for most people in the West, but fibre-maxxing as an extreme principle offers no additional benefit beyond meeting the recommended 25 to 30 grams per day through ordinary foods such as legumes, vegetables and wholegrains.
Is eating organic 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 through meat. For pregnant women and young children, that is the strongest concrete argument.
Are smoothies and fresh juice just as healthy as whole fruit?
Whole fruit beats fruit juice: more fibre, greater satiety and fewer free sugars. Smoothies fall somewhere in between, but are not equivalent to whole fruit either.
How healthy are yoghurt and dairy for your heart and bones?
Yoghurt and dairy are a perfectly good choice for bone health for most people, and are likely neutral to mildly beneficial for the heart. Opt preferably for fermented products such as yoghurt, and keep an eye on your total saturated fat intake if you have an elevated cardiac risk.
Are diet sodas and artificial sweeteners bad for you, and if so, why?
Diet soda and artificial sweeteners have not been proven harmful, but the signals are not reassuring enough to justify unlimited use. If you want to reduce your sugar intake, drinking water is at least reliably helpful.
How many vegetables do you really need per day?
Five servings of vegetables and fruit per day offers the best protection, with non-starchy vegetables counting and juice and potatoes not. More than five servings adds nothing.