Milk...Does It Really Do a Body Good?

Suzanne Holden, Dietitian

Those of you fortunate enough to have been touched by Suzanne's kind and unselfish nature won't be surprised to know that she is waiting to hear about a 2-year assignment with the Peace Corps. She has left the Triangle to spend some time with family and hopefully volunteer with vegetarian friendly organizations in the meantime. Best wishes to Suzanne and a fond farewell till she returns! --Dilip

"Milk builds strong bones", "Nature's perfect food", "Got Milk?" .... We're all familiar with the National Dairy Council's vocal advertising. Most Americans consume dairy products each day, and believe that lack of dairy in the diet puts one at serious health risk. However, when we take a closer look, the truth is just the opposite. Dairy products are full of contaminants and their consumption has been linked with a variety of health problems. Leaving aside ethical and other arguments against the use of milk, let's look at some of the health issues.

Osteoporosis

You may have heard that dairy consumption prevents osteoporosis, the weakening of bones. What the dairy council has conveniently neglected to tell us is that osteoporosis rates are highest among the biggest milk consumers - industrialized western nations (1).

The truth is that osteoporosis is a disease involving calcium balance, rather than solely calcium deficiency. Total calcium balance is affected by calcium absorption (15%), calcium intake (11%), fecal calcium excretion (23%), and urinary calcium excretion (51%) (2). Minimizing calcium loss in the urine may be difficult for those on the standard American Diet (S.A.D.), but those choosing a plant-based, whole foods diet are in a different league. Research has repeatedly shown that high protein intakes cause increased urinary calcium losses. Not surprisingly, most omnivorous Americans eat over twice the Recommended Dietary Allowance (RDA) for protein. Other dietary culprits include excessive intake of sodium (3) and caffeine (4). So, though dairy products are good sources of calcium, simply drinking milk does not correct the underlying causes of osteoporosis in America. Think of it as adding money to a piggy bank with a hole in the bottom!

The Calcium Question

It is likely that an individual consuming a plant-based, whole foods diet moderate in protein and low in salt, has lower calcium needs than one consuming the S.A.D. However, until more research is done, it is recommended that vegans strive to meet the RDA for calcium intake. This is easily achieved with daily consumption of high-calcium low-oxalate plant foods.

Strict vegetarians must ensure adequate vitamin D, which aids in calcium absorption. Good sources include vitamin D fortified products (like soy and rice milks, as well as certain cereals) and exposing one's face and hands to direct sunlight for 10-15 minutes per week. It is also important for all Americans, regardless of dietary preferences, to incorporate physical activity into their daily routines in order to maintain and build bone strength.

Some High-Calcium Plant Foods Broccoli Collards, turnip, or mustard greens Kale Bok choy Tofu coagulated with calcium Fortified rice or soy drinks Fortified orange juice Blackstrap molasses Figs

Ovarian Cancer

Galactose, a simple sugar broken down from the milk sugar lactose, has been associated with cancer of the ovary (5). It has been estimated that 10% of the population lacks an enzyme responsible for metabolizing galactose, leading to the accumulation of the sugar in organs such as the ovaries. This is thought to trigger a series of events leading to higher circulating hormone levels, which may promote ovarian cancer (6). Foods highest in lactose include yogurt, skim milk, ice cream, and cottage cheese.

Breast Cancer

Breast cancer rates have been correlated with intake of dairy products in many population-based studies. According to the Physicians Committee for Responsible Medicine (PCRM), cow's milk is a "cocktail of disease-causing chemicals", and there are several hypotheses for the dairy-cancer link (7). Excess estrogen is known to increase cancer cell replication. Not only does milk contain traces of cow's estrogen, but the fat contained in milk, as in any food, increases the production of estrogen in a woman's body. Milk is also rich in IGF-1, a growth factor which causes multiplication of cancer cells in test tube studies; we don't yet know the extent to which humans absorb cow's milk IGF-1. Compounding potential problems, many dairy farms now use BGH (bovine growth hormone), which raises IGF-1 concentrations in milk, in order to increase milk production.

Anemia

If infants are fed cow's milk, blood losses from the intestine may occur resulting in anemia (8). In children, iron deficiency may result from excessive intake of cow's milk due to its displacement of the intake of iron-rich foods in the diet. Also, nutritionists often suggest that anemic individuals not consume milk with iron-rich foods since calcium can significantly reduce iron absorption (9).

Lactose Intolerance

Approximately 2/3 of the world's population is not able to digest the milk sugar lactose (10). Common symptoms experienced after dairy consumption include bloating, gas, diarrhea, and nausea. In many parts of the world, dairy products are not consumed or play limited roles in the diet.

Cataracts

The lactose metabolite galactose has been speculated to play a role in cataract formation (11). Galactose may be converted into galactitol, which is thought to damage the lens structure of the eye and lead to cataracts (12).

Insulin Dependent Diabetes Mellitus

Genetically susceptible infants who consume cow's milk may be at increased risk for childhood onset diabetes. A specific protein found in dairy products may spark an immune reaction which destroys pancreatic insulin-producing cells (13). One study found that children who regularly consume milk have a twofold increased risk of diabetes (14). However, this research isn't conclusive.

Colic

Some infants are sensitive to the proteins in cow's milk, and experience colic as a result of milk consumption. Their discomfort may result from feeding of cow's milk, milk-based infant formula, or breast milk from a mother who drinks cow's milk (15).

Allergies and Asthma

Milk is known to be a common allergen. According to PCRM, respiratory problems, skin conditions, canker sores, and other health problems can be caused by intake of dairy products. For those with allergies and asthma, entirely cutting dairy products from the diet for a trial period may be worth trying.

Heart Disease

Most dairy products have excessive saturated fat, which is strongly linked with heart disease. Some choose margarine over butter, but margarine has been hydrogenated, causing it to contain unnatural trans- fats, which have also been linked with heart disease. All fats (whether margarine, butter, or oil) contain approximately 13 g fat/T; but the more liquid the fat, the less percent is saturated. Mono-unsaturated fats, such as olive, canola, and peanut oils, are better for the heart than saturated fats. The best bet is to skip both butter and margarine, and choose extra virgin olive oil or non-hydrogenated spreads - or, even better, simply enjoy the natural taste of the food!

Other Considerations

*Pesticides in animal feed become concentrated in animal flesh, and are excreted in an animal's milk.

*Humans who consume the products of animals fed antibiotic-laced feed may acquire antibiotic resistance.

*Milk is fortified with vitamin D, which is toxic in high doses. (When synthesized by our skin during sun exposure, however, vitamin D is not toxic.) In 1992, eight people were diagnosed with hypervitaminosis D after drinking improperly fortified milk (16). Concerns have been raised that the vitamin may not be adequately mixed when fortification of large batches of milk occurs. The New England Journal of Medicine reported that only 12% of 42 milk samples analyzed fell within expected ranges for vitamin D levels (17).

Milk-drinking in our society is a cultural norm that most people do not question. However, it defies rationality to assume that anyone besides a calf has a physiological need for cow's milk. It appears that the most prudent milk mustaches to wear are those made from soy, rice, almond, or oat milk!

Editor's Note: Check out http://www.veg.on.ca/cowsmilk.html for additional material

References

1. Calcif. Tissue Int. 1992;50:14-18.

2. NIH Consensus Conf. on Optimal Calcium Intake June 1994 Bethesda, MD.

3. J Hypertens. 1993;11:781-785.

4. J Lab Clin. Med. 1982; 99:46-55.

5. Lancet. 1989; 2:66-71.

6. PCRM: Good Medicine: Autumn 1996 p.13

7. PCRM: Good Medicine: Winter 1997 pp. 12-15.

8. J Pediatr. 1981; 98: 540-545.

9. Eur J. Clin Nutr. 1991; 46: 317-327.

10. Dig. Dis. Sci. 1989; 23: 963-980.

11. Nutr Rev. 1979; 37: 337-343.

12. Nature(London) 1959; 184: 194-195.

13. Diabetes Care 1993; 17: 13-19.

14. Diabetes Care 1994; 17: 1488-1490.

15. Pediatrics 1991; 87(4): 439-444.

16. NEJM 1992: 326: 1173-1177.

17. NEJM 1992: 326: 1178-1181.