The Great Dairy Debate Is dairy healthy for you or not? It isn t black and white
Dairy (sticky note affinity analysis) Benefits Concerns
Learning Objectives Identify nutrients found in different dairy products List current guidelines regarding dietary fat and dairy Summarize evidence for and against including dairy in your diet Make informed decisions about including dairy in your diet
Outline What is in dairy? What do the Dietary Guidelines say about dairy? What about the current research? How to include dairy in a healthy and balanced diet.
What s in the Dairy group?
What counts as a serving? 1 cup of milk or yogurt 1.5 ounces of cheese ½ cup of cottage cheese (???)
What s in dairy? Vitamins and Minerals Calcium Vitamin D fortified Potassium Energy Carbohydrate (lactose) Protein Fat - depends on the cows Probiotics depends Added sugar - depends 1 cup of milk = ~230 grams
What about things not on this list?
What about when cows are treated with antibiotics and hormones like BST? Some suggest that the presence of steroid/growth factor hormones in dairy products may be a risk factor for hormone sensitive caners such as breast and prostate cancer. In a meta-analysis of observational studies, all dairy, but not milk consumption was associated with a 15% reduced risk of breast cancer (Dong et al., Breast cancer Res Treat. 2011;127(1):23-31). Production practices were not controlled for. Fear of antibiotic resistance in humans if too many antibiotic are used to treat cows. US is tightening regulations.
BST is a large protein and are digested by protein in the human gut when ingested. The BST in milk never makes it to our blood!
USDA certified organic milk Cows can t be treated with hormones. Cows can t be treated with antibiotics. Feed has to be grown without chemical fertilizers, pesticides or genetically modified seeds. Cows must get at least 30% of their diet from pasture grass during the four month grazing season.
What about those with lactose intolerance? What is it? A deficiency of lactase, the enzyme that digests lactose into glucose and galactose prior to absorption. 30 minutes after eating dairy diarrhea, nausea, cramps, bloating, gas
3/4 of the world is intolerant to lactose
What about those with lactose intolerance? What to do? Can also occur after an illness or surgery to the small intestine. You grow into, not out of lactose intolerance. More common as you age. People can usually eat yogurt and some cheese (aged, hard is usually your best bet) without distress. Lactaid pills, or decreased lactose content products can help. Use dairy alternatives soy or nut milks, etc.
What s in dairy? Vitamins and Minerals Calcium Vitamin D fortified Potassium Energy Carbohydrate (lactose) Protein Fat - depends on the cows Probiotics depends Added sugar - depends 1 cup of milk = ~230 grams
Dairy fat contains > 400 distinct fatty acids, including many unique to dairy fat ~ 70% are saturated ~ 25% are mono-unsaturated ~ 2% are poly-unsaturated ~ 3% are trans fatty acids
Fatty acids The building blocks of dietary fats Made up of a carboxyl group (COOH) and a chain of carbons and hydrogens (C-C-C ) Saturated no double bonds Unsaturated at least one double bond Polyunsaturated Monounsaturated Trans
Eating more of which of the following fatty acids are associated with increased risk for cardiovascular disease? A. Monounsaturated B. Polyunsaturated C. Saturated D. All fatty acids are associated with increased risk for cardiovascular disease
Eating more of which of the following fatty acids are associated with increased risk for cardiovascular disease? A. Monounsaturated B. Polyunsaturated C. Saturated D. All fatty acids are associated with increased risk for cardiovascular disease
Milk from cows fed grass has a healthier fat profile than does milk from cows fed grain
What do the current Dietary Guidelines say about dairy?
* Limit calories from added sugar and saturated fats, and reduce sodium
Include fat-free or low-fat dairy, including milk, yogurt, cheese, and or fortified soy beverages Limit saturated fat to <10% of total calories
A flaw in the logic?
The health properties of individual fatty acids depend on the chain length as well as the degree of saturation. Butyric acid (C4:0) is a short chain saturated fatty acids Butyric acid is found in milk, butter and cheese; it is also made by bacteria in your colon through the process of fermentation Butyric acid has the distinctive smell of human vomit Butyric acid has many health benefits (anti-inflammatory, antimicrobial, increases cell proliferation and protects again colon cancer) and does not increase risk for cardiovascular disease
Could the benefits of dairy outweigh the risks of dairy?
Nutrient vs. food vs. dietary pattern approach
An example from the peer-reviewed evidence
A higher intake of SFA from dairy (except butter) was associated with lower risk for cardiovascular disease A higher intake of SFA from meat was associated with higher risk for cardiovascular disease
Adults who consumed 11-14 servings of dairy products per week had 5-16% lower levels of biomarkers of inflammation compared to those who consumed < 8 servings per week.
Dairy foods have a higher percent of shorter chain SFA than does meat. Fat in milk occurs in globules that are emulsified in the liquid component of milk. These globules have a unique membrane. This membrane the milk fat globule membrane has many bioactive components.
milk fat globule membrane (MFGM)
Observational studies suggest that consumption of dairy products has a neutral or beneficial effect on cardiovascular risk and obesity. High fat dairy was inversely associated with obesity in 11 of 16 studies, Kratz et al., Eur J Nutr. 2013;52(1):1-24.
Some things to consider Observational studies have a high potential for confounding. (reporting bias, differences in make up of diary foods, differences in what is eaten with different types of dairy foods) We need more evidence from randomized controlled trials that directly compare full-fat with lower-fat versions of different dairy products (milk vs. cheese vs. butter, etc.; fermented vs. not fermented; grass fed cows vs. grain fed cows)
Healthy adults Usual dairy intake or <1.5 servings per day in the low dairy condition vs. 2.5 5 servings per day in the high dairy condition
Both low-fat and whole-fat dairy increase were associated with increased weight.
Increases in neither lowfat or whole-fat dairy were associated with cardio-metabolic biomarkers of risk.
What about diabetes?
What about diabetes? Observational studies suggest that dairy intake is associated with reduced risk of type 2 diabetes and metabolic syndrome. The effect is strongest and most consistent for yogurt (> 200g/d; Wu et al. Nturients. 2017;9(2):315); weakest for milk. There is some evidence pointing specifically to full fat (not low fat) cheese and fermented dairy foods as being protective. (Ericson et al. AJCN, 2015; doi: 10.3945/ajcn.114.103010)
Those consuming in the highest quintile of high fat dairy had 28% lower risk of T2D compared to those in the lowest quintile of intake. Short and medium chain SFA (found in dairy) were also associated with decreased risk.
Nutrient vs. food vs. dietary pattern approach
Plan a healthy balanced 1-day diet for yourself that includes dairy (concentrate on the variety of dairy and the other foods that are also included); share this with your table or neighbor.
Summary Dairy foods are nutrient dense and complex. The content of fatty acids in dairy depends on what the cow eats. Not all saturated fats are associated with risk for disease. Little evidence supports associations between dairy and increased risk for CVD, obesity, or diabetes. You shouldn t be avoiding dairy because you want to lower your risk for these things.
Take home message If you tolerate and enjoy dairy products, go for it! Dairy can be an important part of a healthy balanced diet. Avoid low-fat dairy products with added sugar; don t be afraid of full-fat varieties of milk, yogurt, and cheese. Butter is still an added fat and provides no benefit. Fermented dairy foods provide additional probiotic benefits.