Dhamma Wheel Buddhist Forum

Instead, people who are lactose intolerant can't digest the main sugar —lactose— found in milk. In normal humans, the enzyme that does so —lactase— stops being produced when the person is between two and five years old. The undigested sugars end up in the colon, where they begin to ferment, producing gas that can cause cramping, bloating, nausea, flatulence and diarrhea.

If you're American or European it's hard to realize this, but being able to digest milk as an adult is one weird genetic adaptation.

It's not normal. Somewhat less than 40% of people in the world retain the ability to digest lactose after childhood. The numbers are often given as close to 0% of Native Americans, 5% of Asians, 25% of African and Caribbean peoples, 50% of Mediterranean peoples and 90% of northern Europeans. Sweden has one of the world's highest percentages of lactase tolerant people.

Being able to digest milk is so strange that scientists say we shouldn't really call lactose intolerance a disease, because that presumes it's abnormal. Instead, they call it lactase persistence, indicating what's really weird is the ability to continue to drink milk.

DR. WALTER C. WILLETT
Chairman of the Department of Nutrition
Harvard School of Public Health (Boston)
Author, “Eat, Drink and Be Healthy”

Also, the recommendation for three servings of milk per day is not justified and is likely to cause harm to some people. The primary justification is bone health and reduction of fractures. However, prospective studies and randomized trials have consistently shown no relation between milk intake and risk of fractures. On the other hand, many studies have shown a relation between high milk intake and risk of fatal or metastatic prostate cancer, and this can be explained by the fact that milk intake increases blood levels of IGF-1, a growth-promoting hormone. The justification for drinking three glasses of milk per day on the basis of increasing potassium intake is also not valid as the extra calories, even with low-fat milk, would easily counterbalance the benefit of the extra potassium. Also, the recommendation for people of all ages to drink three servings of milk per day is very radical and would double dairy production if adopted; this would have huge environmental impacts that would need to be considered.

In a number of countries, including Japan, India, and Peru, the average daily calcium intake is only 300 mg. That’s much less than the 1,000 mg recommended for adults between the ages of 19 and 50 in the U.S., yet the incidence of bone fractures in these countries is very low. In addition, evidence from some large studies indicates that calcium doesn’t actually reduce the risk of osteoporosis as we once thought. For example, in two studies conducted by the Harvard School of Public Health, participants who drank one glass or less of milk per week had no greater risk of breaking a hip or forearm than those who drank two or more glasses of milk per week.

After reviewing this data and discussing it with Walter Willett, professor of nutrition and epidemiology at Harvard University’s School of Public Health, I’m revising my calcium recommendation downward. In the past, I recommended 1,200 mg daily in divided doses and 1,500 mg for postmenopausal women who were not on hormone replacement therapy. I now suggest that women supplement with 500 to 700 mg of calcium citrate in two divided doses taken with meals, for a total daily intake of 1,000-1,200 mg from all sources. For men, I now suggest aiming for 500 mg from all sources, and that men probably do not need to supplement (higher amounts have been linked to increased risks of prostate cancer). Men should also watch their dairy intake. The Harvard study determined that men who drank two glasses of milk a day (that translates to about 1,000-1,200 mg of calcium) had twice the incidence of developing advanced prostate cancer.