Thinning bones has less to do with the menopause than with Western dietary practices, but it can largely be prevented by diet and regular exercise.
Although osteoporosis was never much of a health issue in previous generations, today it is a major public health concern, now affecting some 25 million Americans and one in four in the UK. There are all kinds of books written about it, and millions of women are swallowing millions of pills to keep it at bay.
The thinning of bones that can indicate risk of fracture, most commonly in old age, can occur from a number of causes. However, news reports about the issue have reduced it to two main causes: lack of calcium and lack of oestrogen. Older, alcoholic men are at serious risk for osteoporosis and bone fractures as well, but it has been women who have been targeted by the marketing campaigns of those who sell drugs and milk products. What we are actually being sold is a large helping of fear. Because of that fear, women are swallowing calcium pills and oestrogen pills by the ton, even if they are not individually appropriate.
One of the most interesting epidemiological aspects of osteoporosis is that it occurs more in cities and in "first world" countries, where these practices are common, rather than in rural areas and "third world" countries, where they are not. Specifically, it occurs more in the European and North American countries where people eat large amounts of milk products, than in the African countries, where people eat almost none. It is lowest in those areas of South Africa where people follow traditional ways of life.
Even though osteoporosis and bone fractures usually occur during the later stages of a woman's life, menopause is not the cause of these problems. They are only temporally related. More important for bone health is how we treat our bodies, and especially what we eat.
There are aspects of our diet that impact on our bones because they cause an active calcium loss, or drain, and over time this drain can cause as much trouble as any nutritional deficiency.
The women I know who have broken bones after menopause generally share two or more of the following characteristics:
Their diet was rich in meats, white flour, sugar, potatoes and tomatoes.
They didn't hesitate to take pharmaceutical medicines, either over the counter or prescribed.
They didn't do much exercise.
They were thin, either because they didn't eat enough or because they dieted to stay that way.
The acid alkaline balance
Acids are substances containing hydrogen atoms that are missing electrons, so their tendency is to go steal electrons elsewhere: that thieving tendency makes them corrosive. In the body, acids generally result from metabolic processes such as moving or breathing: these acids are either excreted, or they're buffered (neutralised) by minerals or mineral salts, which in turn are considered alkaline (or basic). For the proper function of our metabolism, our blood plasma has to be slightly alkaline, at a pH of about 7.45 (a pH of 7 is neutral, below 7 is acid, above it is alkaline). This is a highly delicate balance.
The more minerals there are in a food, the more they alkalise the body. Protein and carbohydrate foods are acid forming because they leave behind an acid residue; acid forming foods include sugar, flour, beans, grains, fish, fowl, meat and eggs. Alkalising foods include fruits, vegetables, sea vegetables, soy sauce, miso and salt.
The trick, of course, is to eat from both groups, and pick the healthier foods from each. Eating too high a proportion of acid forming foods will draw minerals out of the bones; while eating a high proportion of alkalising foods often tends to create cravings for sweets, as many vegetarians will attest to.
The buffer foods are milk products and tofu (if made with calcium carbonate); they will balance either side, because they contain both calcium (alkalising) and protein (acid forming). Thus, if a diet is high in sugar, flour, and/or meats, yet low in vegetables, dairy produce will help alkalise the body because of its calcium content. Conversely, if a diet is high in alkalising fruits, vegetables, and potatoes, yet low in protein or grains, dairy products will provide supplementary acid forming protein.
For people who prefer not to use milk products, the solution is to consume instead plenty of dark green, leafy vegetables (kale, collards, mustard greens, watercress, arugula), roots (carrots, turnips, parsnips, radishes), broccoli, squash and especially chopped parsley. Parsley contains both calcium and vitamin C, as well as ergosterol, a precursor to vitamin D, which helps absorb and utilise the calcium. Although spinach is rich in calcium, it is also high in oxalic acid, which interferes with the absorption of calcium.
Acid forming foods promote a tendency toward acidosis in the bloodstream; to counteract this acidosis, calcium and other minerals will be immediately withdrawn from the bones. Thus, bone resorption (breakdown) would increase to rebalance the blood, and calcium and other minerals would be excreted in the urine. Studies done on mice at the University of Rochester School of Medicine and Dentistry (Curr Opin Nephrol Hypertens, 1993; 2: 588-96) have shown that calcium does indeed leave the bones when they are in an acid environment. In other words, metabolic acidosis stimulates bone resorption and inhibits bone formation.
An increase in alkalising foods can balance this equation, by replacing the minerals that have been "borrowed" from the bones. However, if the diet is low in vegetables and other mineral rich foods, and if this persists for year after year, the amount of calcium and other minerals needed for bone deposition would be too low, and slowly the needs of bone resorption would exceed the the amount of incoming calcium.
Both too much and too little protein can cause trouble with the bones. Vegetarians have been shown to have higher bone density than omnivores, or people who eat everything. In one study (Amer J Clin Nutri, 1972: 25: 555-8) the mean bone density of the 70 to 79 year old vegetarians was greater than that of the 50 to 59 year old omnivores. Therefore, it is considered that vegetarians have a lesser risk of osteoporosis. But another way to interpret these studies is to note the rest of the dietary context: it could mean that the omnivores eat too many sweets and not enough greens and other plant foods. A 1997 Norwegian study found that there was an elevated risk of fracture in women with a high intake of protein and a low calcium intake.
Dr T Colin Campbell of Cornell University, in collaboration with the Institute of Nutrition and Food Hygiene of the Chinese Academy of Preventative Medicine in Beijing, conducted a famous study of the dietary patterns and nutritional status of Chinese people in the early nineties (Bol Assoc Med P R, 1990; 82: 132-4). That study clearly showed that the composition of urinary acids and calcium in middle aged and elderly women is influenced considerably by their dietary intakes. The consumption of acid forming foods such as animal protein increased calcium excretion in the urine, which indicates bone mineral loss. Plant protein intake was not related to urinary calcium excretion.
This finding may be one of the reasons why vegetarians have less osteoporosis than meat eaters. However, I am convinced that acidosis can also occur from too much flour or sugar. Metabolic acidosis from excess acid forming foods in general would then have a calcium wasting effect, or drain. The theory that protein foods such as red meat cause bone loss was debunked by the studies of Herta Spencer of the Veterans Administration Hospital in Hines, Illinois, in the 1980s (cited in Health Journal, Summer 1996). Dr Spencer found that studies correlating calcium loss with high protein diets used fractionated, isolated amino acids from milk or eggs; complex dietary proteins such as red meat did not cause calcium losses.
In the last quarter century we have focused on the excess of animal proteins in the diet and found them damaging. Many studies of protein foods determined that their acid residue is bad for the bones. However, Weston Price, DDS, author of Nutrition and Physical Degeneration, who traveled all over the world in the early 1930s studying the health and diet of traditional societies, observed that excellent bone health is found in traditional populations with diets high in fish and meats, so long as they also contain plenty of animal fats and vegetables.
Although much attention has been paid to protein, refined carbohydrates have received relatively little notice, mostly because of the unfortunate viewpoint that "all carbohydrates are equal". In traditional societies, such as those examined by Dr Price, osteoporosis only appears in countries where the diet includes the habitual use of refined foods. The natives who remained on their traditional diet, regardless of the amount of protein consumed, were, on the other hand, found to be without these defects and in good health.
As their metabolic byproducts include carbonic acid, carbohydrate foods, particularly refined carbohydrates, are seriously acid forming. The regular consumption of white flour, white rice and refined sugar will, therefore, contribute mightily to bone weakness; these are, without a doubt in my mind, probably your worst calcium drainers. Perhaps that explains the high rates of osteoporosis in Western countries whose inhabitants, in addition to dairy and meats, also consume a high proportion of white breads, sweet snacks and pastries.
Refined white sugar also interferes with the absorption of calcium and magnesium and so contributes to osteoporosis even further.
A number of studies have shown that caffeine intake is related to both fractures and calcium depletion. A six year study by Stampfer and Colditz in the early eighties, completed at the Department of Medicine of Brigham and Women's Hospital in Boston, followed 84,484 women aged 34 to 59, and found that those with a higher caffeine intake (five or more cups of coffee daily) had an almost three times higher risk of hip fractures (Am Clin Nutri, 1991; 54: 157-63).
Caffeine consumption increases the excretion of calcium as well as magnesium through the urine, which indicates bone loss. Young women seem to be able to compensate for this loss and make it up faster through increased and more efficient calcium absorption from the intestines. Older women, on the other hand, with age and hormone related calcium imbalances, do not seem to be able to compensate as efficiently, and are at higher risk for thinning bones, especially if their calcium intake is low.
According to a study done at the Department of Family and Preventive Medicine at University of California at San Diego, a lifetime equivalent of two cups of coffee per day is associated with decreased bone density at both the hip and the spine in older women if they don't also drink milk (JAMA, 1994; 27: 280-3). (Moderate daily milk consumption, about one glass of milk per day, seems to counterbalance somewhat the calcium wasting effect of caffeine.)
The concept that the nightshade vegetables affect calcium balance has been put forth for over 20 years by Dr Norman Childers, a professor of botany at the University of Florida at Gainesville and formerly of horticulture at Rutgers University. The nightshades comprise a family named Solanaceae, which includes potato, tomato, aubergine, red, green, chili and other hot peppers, paprika, and tobacco. Professor Childers has shown that nightshade consumption contributes to osteoarthritis because these plants contain substances called alkaloids, which disturb the calcium metabolism and tend to remove calcium from the bones, causing aches, pains, even deformations.
It has been my speculation since the early 1980s that people eat so many nightshades simply to counterbalance their consumption of milk products, which have more calcium than human beings need. Theoretically, then, dairy products and nightshades are opposite and complementary: if you eat one, you need the other. Conversely, if you stop eating one (say, dairy), you might do well abandoning the other, or else there may be repercussions in the body's calcium balance. Many of my students and acquaintances have found that if they keep eating nightshades in a low fat, dairy free diet, their joints begin to ache.
I haven't found any studies that directly link osteoporosis and nightshades. Nevertheless, it may be sensible to pay attention to them because of their ability to affect calcium balance. For those at risk for osteoporosis, an occasional potato or tomato may not cause any trouble; however, it may be a good idea to refrain from relying heavily on these vegetables in the diet. In all cases in which I enquired, women with osteoporosis and a history of bone fractures relied on heavy daily use of potatoes as a major source of starch, and tomatoes as both a flavouring and a raw vegetable.
Annemarie Colbin's latest book, Food and Our Bones (Dutton-Plume, 1998), published in America, is available to WDDTY readers through her internet website at www.foodandhealing.com or by writing to Natural Gourmet, 48 W 21st St, New York, NY 10010 USA. Tel: 212-645-5170). $13.95 plus postage and handling.