- Milk and other diary products such as yogurt, cheese, and sour cream are good sources of calcium, potassium and vitamin D.
- New studies provide insights about dairy products that reaffirm the absence of harmful health effects.
- Large population studies show a relationship with dairy fat consumption and higher blood levels of odd-chain saturated fats and unlike many even-chain saturated fatty acids, are metabolized differently and are associated with less cardiovascular diseases and type 2 diabetes.
Skim, low-fat and whole milk are all processed similarly in the United States. In the case of non-fat milk the cream is separated from the whey but not added back. Low-fat milks may contain 1% or 2% fat, while whole milk contains 3.25% fat.
Surprisingly, cup for cup, whole fat milk contains fewer carbohydrates than low-fat or skim because more of its volume is made up of fat, which does not contain lactose.
Doctors Walter Willett and David Ludwig from the Harvard School of Public Health, have questioned the current logic of our current dietary guidelines that continues promote low-fat and skim milk over whole milk to our children — especially when it comes to the growing epidemic of childhood obesity and diabetes (JAMA Pediatrics, Viewpoint 2013). Low-fat chocolate milk, for example may be a problem when sugary chocolate (or strawberry) flavorings are added to low-fat and skim milk (to make up for the loss of taste when the fat is removed). The amount of added sugar can increase by as much as 14 grams per cup -that’s an additional 60 calories!
- National recommendations, including The National School Lunch Program have for years encouraged children and adults to drink skim milk but a deeper look at the scientific evidence is raising new insights and a recent study suggests that whole milk consumption may be associated with less weight gain in children (Scharf RJ et al. Arch Dis Child. 2013;98(5):474-488).
Saturated dairy-fat: weight gain and diabetes?
The issue of reducing fat and sugar calories for better weight control with healthier food and beverage choices is appealing. This is especially important for our children when it comes to what they drink. Sugar-sweetened beverage consumption is an agreed upon major factor related to childhood obesity and diabetes. Ask any parent, when it comes to milk and the call to drink non-fat or skim milk has been very clear for decades. New studies should change this since decreasing fat intake with non-fat, or skim milk or non-fat yogurt does not help with weight loss -most likely since reduced-fat foods tend to have less ability to make us feel “full” -this is called a lower satiety value and too often provides a signal to eat more. Additionally, observational evidence does not support the hypothesis that dairy fat or high-fat dairy foods contributes to obesity or metabolic risk such as in prediabetes (metabolic syndrome) or type 2 diabetes.
High-fat dairy consumption within typical dietary patterns turns out to be associated with a lower obesity risk.
A 2013 study in the Scandinavian Journal of Primary Health Care looked at the dairy intake and obesity rates of more than 1,500 middle-aged and older adults. High fat butter, milk, and cream consumption were associated with lower obesity rates compared to low fat dairy diets. An extensive review of 25 available studies reported in the European Journal of Nutrition, 2013 confirmed the lack of relationship between high-fat dairy consumption and obesity, cardiovascular, and metabolic disease. But don’t think of dairy as a health food; the warnings about dairy and saturated fat as evil are just not backed up by the evidence.
Some recent studies tell us that saturated fats can affect health differently depending on the number of carbon atoms -odd or even can. The warnings to restrict dairy products as whole milk, yogurt and cheeses may not be correct and saturated fats from dairy are measurable in the blood as odd-chain saturated fats. New research from the Medical Research Council (MRC) Epidemiology Unit at the University of Cambridge shows that the risk of new type 2 diabetes is lower in people who have higher blood levels of of odd-chain saturated fatty acids that come primarily dairy products compared to people who did not have this marker of higher dairy consumption. Saturated fats from non-dairy sources such as processed foods, margarine, and meat are even-numbered (the most common is palmitic acid) and was associated with more diabetes.
According to Dariush Mozaffarian, MD, DrPH, dean of the Friedman School of Nutrition Science and Policy at Tufts University, Boston, “The message from this study is that saturated fatty acids are not only different but have opposite relationships with diabetes risk.”
It is known that increased childhood and adolescent milk consumption benefits peak bone mass and would naturally be expected to help decrease the future risk of osteoporosis (weak bones) and bone fractures later in life. The facts sometimes have a way of spoiling a great idea and a look at some recent evidence on bone health is revealing. A recent 22 year follow-up study from the Harvard School of Public Health by Dr. Walter Willett (JAMA Pediatr 2014;168(1):54-60) showed that increased milk consumption during teen years was not associated with reduced hip fractures in older adult men and women -and for men there was an actual increased fracture risk with increased milk consumption. This same group (and others) showed that increased adolescent milk intake was positively associated with increased adult height.
Further research is ongoing exploring the concept that the gains in bone health with calcium or dairy supplementation in children and adolescents may not persist after treatment is discontinued. The National Health and Nutrition Examination Survey (NHANES) a very large ongoing population survey does confirm that cow’s milk in early life (before age 5 years) increases height and suggests that insulin-like growth factor (IGF-1) may be the molecule in milk that is important to this relationship with increasing height.
Milk hormones and calcium?
Insulin-like growth factor-1 (IGF-1) is a naturally produced human protein found in our saliva, digestive secretions and is also found in cow’s milk (and surprising to some IGF-1 levels are increased in response to soy milk). Minute amounts of IGF-1 (compared to the much higher amounts we produce naturally) are ingested from milk. Virtually all ingested amounts of IGF-1 are destroyed during the process of digestion and there is a low biological likelihood it could cause harm. There have been nevertheless, been speculative links of IGF-1 to cancer risk.
Naturally occurring growth hormones help cows to make milk. These hormones called bovine somatotropin (BST) or bovine growth hormone (BGH) are proteins that like other milk proteins are destroyed by digestion and do not have biological effects. Furthermore, pasteurization inactivates or destroys most of the these milk hormones even before digestion occurs. In 1993 the FDA approved artificial (recombinant) growth hormones in dairy cows in order to increase commercial milk yields from dairy cows and “concerns” about its health effects on humans soon were heard. The question of safety about growth hormones (BST or BHG) in milk and possible harm remains an ongoing topic in some circles.
The American Cancer Society statement on IGF-1 in milk, whether the milk is produced naturally or by growth hormone (recombinant or rBGH) treated cows is reassuring and finds no consistent cancer risk related to IGF-1. Nevertheless, mixed messages about milk and cancer risk abound with some reports suggesting an increased risk of advanced prostate cancer among adult men who drank more than 3 cups of milk compared to those men who didn’t. A signal of increased risk of colorectal cancer with milk has also been reported but was refuted by other studies that show the opposite with a decreased cancer risk.The question cancer risk is far from conclusive and some have raised the question of whether the association if valid could be re-framed as one related to higher calcium levels. The bottom line is that the cancer risk is not compelling and milk and calcium (from our diet or supplements) are not likely players in increasing any cancer risk (World and Cancer Research Fund/American Institute for Cancer Research. Food, Nutrition, Physical Activity, and the Prevention of Cancer: A Global Perspective. 2007. American Institute for Cancer Research, Washington, DC).
The composition of fats in milk can be influenced on whether milk is organic or from grass fed cows. Research shows that whole organic milk from grass-fed cows is a higher (by 62%) in omega-3 fatty acids than conventional whole milk. Omega-3 fatty acids are an essential fat with health benefits. Whole milk from organic, grass-fed dairy products may actually offer some modest health benefits not seen in nonfat dairy as a result of increased levels of this essential fatty acid.
Lactose intolerant or milk allergy?
In the United States ethnic groups such as African Americans, Hispanics/Latinos, American Indians, and Asian Americans are more likely than other ethnic groups to develop lactose deficiency. People often confuse lactose intolerance with milk allergy. Lactose intolerance is a condition in which people have digestive symptoms — such as bloating, diarrhea, and gas — after eating or drinking milk or milk products. Those with this condition have a deficiency of an enzyme called lactose and have trouble metabolizing (or breaking-down) milk sugar called lactose. Some with this deficiency may still find some milk products tolerable and others not and must not consume any foods with milk sugar (lactose). Since milk and milk products are major sources of calcium and vitamin D it is possible to become calcium deficient in calcium and become at risk for less dense bones that could become more likely to fracture later in life (osteoporosis). Calcium and vitamin D supplements may be needed. Formal testing for lactose intolerance is recommended and is valuable to confirm the diagnosis (and not miss some other disorder that might be responsible for similar symptoms).
Lactose is present in many food products and in some medications. Lactose is in all milk and milk products and many food products may contain small amounts of lactose that may not be obvious. People who have digestive symptoms after consuming a small quantity of lactose should be aware of the following products:
- bread and other baked goods
- waffles, pancakes, biscuits, cookies, and the mixes to make them
- processed breakfast foods such as doughnuts, frozen waffles and pancakes, toaster pastries, and sweet rolls
- processed breakfast cereals
- instant potatoes, soups, and breakfast drinks
- potato chips, corn chips, and other processed snacks
- processed meats such as bacon, sausage, hot dogs, and lunch meats
- salad dressings
- liquid and powdered milk-based meal replacements
- protein powders and bars
- nondairy liquid and powdered coffee creamers
- nondairy whipped toppings
People can check the ingredients on food labels to find possible sources of lactose in food products. If a food label includes any of the following words, the product contains lactose:
- milk by-products
- dry milk solids
- nonfat dry milk powder
Those with milk allergy can develop hives with exposure to milk and milk products. About 2-3% of children younger than 3 are allergic to milk and most children are likely to outgrow their milk allergy before they are 16. A delayed introduction of allergenic foods such as cow’s milk until age 1 to prevent future allergy is no longer recommended by international experts. New guidelines also state that pregnant women no longer need to avoid essential foods such as milk and eggs during pregnancy.
There is a consistent message that all saturated fat foods are not harmful and different saturated fats carry differing health effects. Whole milk and dairy products may not be quite the villain we were once led to believe and it is obvious that scientists, physicians and media writers have often gotten it wrong. Foods containing high saturated fats should not be lumped together since dairy associated odd-chain saturated fatty acids are associated with less type 2 diabetes and when it comes to drinking whole milk compared to skim there is more weight gain with the non-fat choice.