Strong bones—is milk really necessary?

Osteoporosis (porous bones due to calcium loss) and reflux are two diseases in vogue, especially among the well off. Sometimes it must seem that if your grandmother doesn’t have osteoporosis and your baby reflux, you are just not with it. Bone is living tissue that is always in flux, constantly being broken down and built up. The state of your bones depends to a great extent on which one of these predominates. In healthy individuals who get enough calcium, vitamin D and physical activity, bone production exceeds bone destruction up to about age 30. After that, destruction typically exceeds production. Preventing osteoporosis depends on two things: making the strongest, densest bones possible during the first 30 years of life and limiting the amount of bone loss in adulthood. Apart from calcium and vitamin D, there are two things in childhood that make bones strong. One is if you are lucky enough to have been breastfed and the other is physical activity. Kids who run around outside in the sun and eat well have strong bones. After age 30, despite the talk about taking calcium and medication, there is little you can do to strengthen your bones. It’s all downhill although you can slow down the process. Because bone is full of calcium, it’s easy to believe all you have to do is take calcium and presto, your bones become strong again. It’s not so simple. The body is more complicated than that. 

 

And because everyone knows milk is full of calcium, everyone assumes,with the help of some judicious advertising, that if you drink plenty milk, either as a child or as an adult, you will strengthen your bones. Those advertisements pushing milk as the answer to strong bones are almost inescapable. But does “got milk?” really translate into “got strong bones?”  As we saw last week, “move on” doesn't always translate into “we gone!”  “He gone” perhaps, but for how long? Whilst getting enough calcium from childhood through adulthood helps build bones up and then helps slow the loss of bone as we age, it is not clear, though, that we need as much calcium as is generally recommended, and it’s also not clear that dairy products are really the best source of calcium. In the USA, really massive amounts of calcium, mainly coming from milk (three glasses a day!), are recommended for adults despite there being little evidence that so much calcium prevents osteoporosis. Other countries recommend much lower doses. The British for example have established calcium requirements for adults that are almost 25 per cent lower than the Americans. The Brits do tend to be a bit more independent of business interests than their cousins across the pond. In other countries such as India, Japan, and Peru where average daily calcium intake is less than a third of the US recommendation for adults, the incidence of bone fractures is quite low and in fact it is true that bone fractures from osteoporosis are most common in those countries with a high intake of milk.

 

One reason for this is that the calcium in milk may not be absorbed as readily as calcium in other foods like fish, green leafy vegetables, such as lettuce and water cress, nuts and seeds as well as in dried beans and legumes.

There are other factors involved. The most important is physical activity. But it must be physical activity that puts some strain or stress on bones. Such “weight-bearing” exercises include walking, dancing, jogging, weightlifting, stair-climbing, racquet sports, and hiking but not swimming. Water supports the bones. Getting enough vitamin D is just as important to bone health as calcium. Skin makes vitamin D from sunlight. It’s hardly necessary for any West Indian to take extra Vitamin D, unless you coat yourself with sunblock and walk around with an open parasol. Those who live above or below 40 degrees latitude, where the sun is weak, need to take vitamin D supplements. Other vitamins are important. One is Vitamin K, which is found mainly in green, leafy vegetables. Low levels of circulating vitamin K have been linked with low bone density, and supplementation with vitamin K shows improvements in biochemical measures of bone health. Vitamin A, usually associated with good vision, is important too, but in a certain form. Too much preformed vitamin A (also known as retinol) can promote fractures. Foods such as sweet potato, carrots and spinach have the best form of vitamin A precursor, beta-carotene, which does not increase your fracture risk. The body needs protein to build healthy bones but again in moderation. As your body digests protein, it releases acids into the bloodstream, which the body neutralises by drawing calcium from the bones, thus weakening them. Finally the ubiquitous sweet drink. Apart from contributing to your weight, people who drink sweet drinks every day have lower bone mineral density than those who drink it less than once a month. Sweet drinks have high levels of phosphorous, which decreases the absorption of calcium and weaken bones. Now you know why people from Toco have strong bones.