Chapter 77
Estrogens versus Phytoestrogens
When a Women’s Health Initiative study found that women in menopause who received hormone replacement therapy suffered from “more breast cancer, cardiovascular disease, and overall impairment,” the call for safer alternatives grew loud. Yes, the Women’s Health Initiative found that taking estrogen brought positives—for example, it relieved menopausal symptoms, improved bone health, and lowered the risk of hip fracture—but its negative effects included an increased risk of blood clots in the heart, the brain, and the lungs, as well as breast cancer.
Ideally, we would need a so-called selective estrogen receptor modulator—something with pro-estrogen effects, for example in the bones, and at the same time anti-estrogen effects in other tissue such as the breast. Pharmaceutical companies are trying to develop something like that, but the phytoestrogens in soybeans such as genistein, which is structurally similar to estrogen, act like a natural selective estrogen receptor modulator. How can something that looks like an estrogen act like an anti-estrogen?
In my video see.nf/phytoestrogens I explain how you can get both with soy, thanks to the discovery of two different types of estrogen receptors in the body—so you get bone strengthening without the risk of clots and cancer. In 2020, a meta-analysis of more than 60 randomized controlled trials of soy phytoestrogens in postmenopausal women found that their bone density in the hip, spine, and wrist improved significantly more than in the control group. In a direct comparison, soy was not inferior to hormone replacement therapy. For example, soy milk was compared in a two-year study with a progesterone skin cream and a placebo. The placebo control group lost significantly in spinal bone density over those two years; the progesterone group lost significantly less. The soy group, however, whose members drank two glasses of soy milk daily, had healthier bones at the end than at the beginning.
Soy milk also has the advantage of lowering breast cancer and prostate cancer risk, promoting gut health, and reducing inflammation as well as DNA damage from free radicals more than rice or cow’s milk. In addition, it can improve insulin resistance and support rehabilitation after a stroke; furthermore, it can increase walking speed, likewise endurance, grip strength, and muscle function, and it lowers blood pressure better than cow’s milk. Soy milk can even lower LDL cholesterol by up to 25 percent in three weeks. Nutritionally, soy milk is the best replacement for cow’s milk in the human diet.
We care about bone mass because we want to prevent fractures. Dairy products can also increase bone density, but that does not show up in a lower risk of hip fracture. Soy foods, however, are reliably associated with a significant 30 to 50 percent lower fracture risk in women. That starts with just a single serving of soy a day—the equivalent of 5 to 7 grams of soy protein or 20 to 30 milligrams of phytoestrogens daily, which is about a cup of soy milk or, better yet, a serving of a whole-soy food such as tempeh or edamame or mature beans themselves. We do not have data on fractures in connection with soy supplements, but it is better anyway to eat whole foods than to take pills or powders, especially because commercially available isoflavone supplements with identical labels showed “huge differences” in isoflavone content when tested.
And the “antinutrients” in beans?
So-called antinutrients are plant components that supposedly hinder the absorption of nutrients. But recently, the concept of “antinutrients” as a whole has been called into question, and some may even be useful. Details can be found in see.nf/milks.
Plant-based bones
Studies show that increased intake of plant foods is associated with increased bone density, while diets of animal products point to a higher fracture risk, which is why one would assume that osteoporosis occurs less often among those who eat plant-based. The data, however, are mixed. In see.nf/vegbone I go into the available evidence from the last 50 years.
Vegetarians and vegans usually have lower bone density compared with meat eaters, but most of this difference disappeared when body size was taken into account. So it is not so much about what vegetarians and vegans eat, but about the fact that they are usually much slimmer.
The risk of hip fractures falls as weight increases. Almost half of all underweight women suffer from osteoporosis, for example, but not even one percent of women with obesity, which makes sense. When you are obese, the body is forced to strengthen the bones to lug around the extra pounds. That is why weight-bearing training is important; it challenges the skeleton continuously. And among vegetarians—especially vegans—obesity is very rare, so it is no wonder that on average they have lower bone density. Does that translate into an increased fracture risk?
In my video see.nf/vegfractures I discuss all the data on fractures, but in brief the answer is yes—and not only because vegans are generally slimmer, but because of potentially too-low vitamin D levels and calcium intake. I recommend that those who do not get enough sunshine take at least 2000 IU of supplemental vitamin D daily and get at least 600 milligrams of calcium daily from calcium-rich plant foods—preferably dark green leafy vegetables low in oxalic acid, which is everything except spinach, chard, and beet greens. (All very healthy, but stingy with calcium.)
Move early and often
For bone health, the rule is that you have to be active to maintain it. That is why astronauts lose one percent of their bone mass per month when they are not on Earth. Their bodies are not dumb. Why waste all that energy on strong bones if you are just floating around and not loading the skeleton? Physical activity is a “widely available, inexpensive, and highly adaptable contribution to bone health.” Even so, some exercises are more efficient than others; I describe that in detail in see.nf/weightbearing.
Stretching—but with caution
Low-intensity activities such as yoga are generally not considered beneficial for building bone, although there are misleading studies claiming otherwise (details at see.nf/yogabones). In fact, yoga could even lead to compression fractures in the spine. Safe exercises include those in which the spine is gently stretched and the legs are straight, such as “Warrior”; you should avoid extreme flexion or extension of the spine (as in a forward bend or “Camel”), stressing the neck (as in “Plow”), or loading the lower back and hip (for example with “one-legged pigeon”); these positions can even lead to fractures in people with normal or near-normal bone density.
A systematic review of more than 9000 yogis showed that the risk of yoga injuries is lower than with higher-impact activities such as running, with one exception: meniscus damage, probably because of positions like Lotus. Hot yoga carries its own risks. See the list of safety recommendations in see.nf/yogarisk.
The single most important thing if you want to avoid osteoporosis-related fractures
Bone density testing is a billion-dollar business, so it is no wonder that osteoporosis and its treatment focus on it. But in women over 65, only 15 percent of low-trauma fractures (from a low fall height) are caused by osteoporosis. Between the ages of 60 and 80, hip fracture risk in men and women increases 13-fold, while age-related loss of bone density only doubles the risk. So 85 percent of the age-related increase in hip fracture risk has nothing to do with measured bone density.
If you do not fall, you will not break even a vulnerable hip. The main reason for fractures, including vertebral fractures, is falls. The discrepancy between men and women in hip fractures is not because men have stronger bones, but because women fall more often. With the simple question “Do you have balance problems?” physicians can predict about 40 percent of all fractures, and that is a higher hit rate than a bone scan for diagnosing osteoporosis. Even an osteoporotic weak bone is strong enough to withstand everyday activities, as long as the excessive load from a fall does not occur. For the spine, it is important when lifting to bend your knees rather than your back.