Low-fat dairy diabetes benefit

May 10, 2005

Hi All,

See the below for a review and then major excerpts from a new low-fat dairy

diabetes

benefits paper.

That trans-fat intake increased with dairy foods seemed to be contrasting.

Ice cream seems to be better than yogurt cream or cheese.

Editorials

The Milk Debate

Janet C. King

Arch Intern Med. 2005;165:975-976.

On January 12, 2005, the Department of Health and Human Services and the

Department

of Agriculture released the 2005 Dietary Guidelines for Americans. One of the

guidelines recommends that Americans " consume 3 cups per day of fat-free or

low-fat

milk or equivalent milk products. " Previous guidelines recommended 2 to 3 cups

per

day. The increase to 3 cups per day was done to help Americans meet the

recommended

potassium intake. In 2004, the Institute of Medicine recommended that Americans

consume at least 4.7 g of potassium per day to lower blood pressure, lessen the

adverse effects of salt on blood pressure, and possibly reduce the risk of

kidney

stones and bone loss.1 Milk is the most prevalent source of potassium in the US

diet, providing 10.2% of the total intake.2

In addition to being a good source of potassium, milk and milk products are rich

in

a number of other nutrients. They are the major source of calcium, phosphorus,

riboflavin, vitamin D, and vitamin B12, and they provide more than 10% of the

total

intake of vitamin A, thiamine, vitamin B6, magnesium, zinc, and protein. Within

the

past 2 to 3 decades, dairy foods have also been shown to reduce the effects of

several chronic diseases, ie, osteoporosis, hypertension, kidney stones, gout,

some

cancers, obesity, and type 2 diabetes. In this issue of the Archives of Internal

Medicine, Choi and coworkers3 report that higher intakes of low-fat dairy foods

lowered the risk of type 2 diabetes in men. Two previous studies showed an

inverse

relationship between dairy intake and insulin resistance in men or in young,

obese

adults.4-5 This is the first study, however, to prospectively show that dairy

consumption lowered the incidence rate of type 2 diabetes in men. The effect was

primarily limited to low-fat dairy foods, with each additional serving consumed

daily lowering the relative risk by 9%. Adjustments for body mass index,

physical

activity, or family history did not alter the magnitude of the result. The data

support adding dairy foods to the list of dietary factors influencing the

development of type 2 diabetes.

Several theories have been proposed to explain the mechanism underlying the

inverse

relationship between dairy consumption and type 2 diabetes. One theory involves

the

insulinotropic properties of whey proteins in milk.6 When skim milk powder is

consumed, the glycemic response is only about one third of the relative insulin

response, demonstrating the insulinotropic properties of milk. Lactose, the

primary

carbohydrate in milk, does not account for the marked insulin secretion.

Instead, it

appears to be due to rapid release of insulinotropic amino acids and incretin

hormones (glucose-dependent insulinotropic polypeptide and glucagonlike

peptide).

Incretin hormones are peptide hormones secreted from the gut that augment

insulin

secretion. Studies show that the incretin effect is normally lost or greatly

impaired in patients with type 2 diabetes. Whey appears to be a particularly

potent

stimulus for the secretion of glucagonlike peptide. It is possible that the

ability

of milk to enhance the secretion of insulinotropic amino acids and incretin

hormone

helped reduce the incidence of type 2 diabetes in men with high intakes of dairy

foods in the study by Choi and coworkers.3 Choi et al3 adjusted for the lower

glycemic index of milk and found that the adjustment did not alter the

association

with type 2 diabetes. However, since milk seems to influence glucose tolerance

more

through its insulinotropic effect than its lower glycemic load, adjustment for

glycemic load should not affect the diary intake–type 2 diabetes relationship.

A second theory regarding how dairy foods reduce the risk of diabetes involves

magnesium. Prospective studies have shown an inverse relationship between the

intake

of magnesium-rich foods, such as dairy foods, and diabetes.7 It has been shown

that

an increase in intracellular free calcium compromises the adipocyte and skeletal

muscle response to insulin. Magnesium acts as a mild physiological calcium

antagonist and thereby may reduce the adverse effect of intracellular calcium

excess

on insulin sensitivity. Adjusting for the total magnesium intake in the study by

Choi et al3 did not alter the association between dairy intake and type 2

diabetes.

However, the range of magnesium intake was narrow. The intake of nuts, one of

the

richest sources of magnesium, ranged from 0.2 to 0.3 servings per day in all

quintiles of calcium intake.

The association between dairy food consumption and body weight has received a

lot of

attention recently.8 There was no evidence in this study by Choi et al3 that

body

mass index varied with milk intake, and adjusting for body mass index did not

alter

the dairy food–type 2 diabetes relationship. The effect of milk products on body

weight has only been studied in two randomized controlled trials. Although both

of

these trials had fewer than 50 subjects, an inverse relationship was observed

between milk consumption and body weight or weight loss. Large-scale randomized

trials or controlled feeding studies are needed to test explicitly the effect of

milk intake on body weight. The 2005 Dietary Guidelines Advisory Committee2

concluded that current evidence is insufficient to claim that milk products are

an

important means of managing body weight.

Milk consumption is also associated with a lower risk for hypertension and

cardiovascular disease.2 In two controlled feeding studies using the Dietary

Approaches to Stop Hypertension (DASH) diet, which includes 3 servings of

low-fat

milk products per day and is rich in fruits and vegetables, blood pressure

dropped

significantly. An analysis of 10 prospective cohort studies on milk consumption

and

vascular disease showed a pooled estimate of relative odds of 0.84 for any

vascular

event. It is interesting that the men in the highest quintile of milk intake in

the

study by Choi et al3 tended to have a lower prevalence of hypertension and

hypercholesterolemia.

Although dairy foods are excellent sources of many nutrients and have several

documented beneficial effects on health, this food group has probably received

more

bad press than any other food group. Two special interest groups are primarily

responsible for the negative reports. The Physicians Committee for Responsible

Medicine and People for the Ethical Treatment of Animals (PETA) claim that milk

consumption is associated with serious diseases, such as lactose intolerance,

type 1

diabetes mellitus, and prostate cancer, and they ignore its attributes.9

Lactose, the sugar in milk, requires the small-intestinal enzyme lactase for

normal

digestion. If insufficient lactase is produced, lactose travels to the large

intestine, where it is fermented by bacteria, producing the gas that is

responsible

for the cramps and diarrhea associated with lactose intolerance. About 25% of

Americans have some degree of intolerance,9 but a number of studies have shown

that

lactase-deficient individuals can tolerate 1 to 2 cups of milk per day if the

milk

is spaced evenly throughout the day and consumed with food. Individuals with

lactase

deficiency also seem to be able to tolerate more dairy foods by gradually

increasing

their dairy consumption. Some individuals are extremely sensitive to lactose,

however, and need to consider lactose-free dairy products; ie, hard cheeses,

yogurt,

and lactase-treated dairy products.

A relationship between milk consumption and type 1 diabetes in children was

first

proposed about 20 years ago.9 As a result, the American Academy of Pediatrics

" strongly encouraged " families with a history of type 1 diabetes to avoid

feeding

commercially available cow’s milk formula to their infants. Children who

inherited

the risk-conferring HLA allele have a higher incidence of type 1 diabetes when

cow’s

milk is introduced earlier in life or when consumption is high. However, it has

been

argued that the heightened risk in children with the HLA allele may be because

they

have an enhanced immunity to dietary proteins in general. Proteins in wheat and

soy

seem to be more potent diabetogens than those found in milk. Until a prospective

randomized controlled trial is completed, the specific role of milk protein in

causing type 1 diabetes in children cannot be ascertained.

The link between milk consumption and cancer is quite complex. Although it

appears

to increase the risk of prostate cancer, it is inversely related to the

incidence of

cancers in the distal colon and rectum.10 An analysis of data from 42 countries

showed that the incidence of prostate cancer was positively related to higher

milk

consumption (r = 0.771). A meta-analysis of 11 case-control studies further

showed

that the combined odds ratio for milk consumption and prostate cancer was 1.68

(95%

confidence interval, 1.34-2.12). The components in milk that account for its

adverse

effect on prostate cancer may differ from those associated with reducing the

risk of

colorectal cancer. Calcium intake was inversely associated with colorectal

cancer.

Also, the milk protein casein has antimutagenic activity. Conjugated linoleic

acid

and lactoferrin, also found in milk, inhibited carcinogenesis in experimental

animals. Two hormones in milk, estrogens and insulin-like growth factor I, may

underlie the positive link to prostate cancer. Estrogen levels are often high in

milk, as pregnant cows produce most of the milk in developed countries. Since

estrogen levels in prostate fluid are correlated with prostate cancer, increased

intake of estrogen from milk could explain the relationship. Insulin-like growth

factor I has also been linked to prostate cancer.

In summary, it is evident that milk contains a number of bioactive components

beyond

amino acids, vitamins, and minerals. Many of these components protect

individuals

from exogenous stresses, toxins, and pathogens; encourage adaptation to the

environment; and promote metabolic regulation, while other milk components cause

negative effects in susceptible individuals. Research shows that the role of

dairy

foods in health is very complex and probably varies with the genotype and

phenotype

of the individual. The study by Choi et al3 is a further reminder of the

potential

importance of dairy intake and the continuing value of research in this area.

Dairy Consumption and Risk of Type 2 Diabetes Mellitus in Men: A Prospective

Study

Hyon K. Choi; Walter C. Willett; Meir J. Stampfer; Rimm; B. Hu

Arch Intern Med. 2005;165:997-1003.

ABSTRACT

Background Diet and lifestyle modifications can substantially reduce the risk

of

type 2 diabetes. While a strong inverse association has been reported between

dairy

consumption and the insulin resistance syndrome among young obese adults, the

relation between dairy intake and type 2 diabetes is unknown.

Methods We prospectively examined the relation between dairy intake and

incident

cases of type 2 diabetes in 41 254 male participants with no history of

diabetes,

cardiovascular disease, and cancer at baseline in the Health Professionals

Follow-up

Study.

Results During 12 years of follow-up, we documented 1243 incident cases of type

2

diabetes. Dairy intake was associated with a modestly lower risk of type 2

diabetes.

After adjusting for potential confounders, including body mass index, physical

activity, and dietary factors, the relative risk for type 2 diabetes in men in

the

top quintile of dairy intake was 0.77 (95% confidence interval [CI], 0.62-0.95;

P

for trend, .003) compared with those in the lowest quintile. Each

serving-per-day

increase in total dairy intake was associated with a 9% lower risk for type 2

diabetes (multivariate relative risk, 0.91; 95% CI, 0.85-0.97). The

corresponding

relative risk was 0.88 (95% CI, 0.81-0.94) for low-fat dairy intake and 0.99

(95%

CI, 0.91-1.07) for high-fat dairy intake. The association did not vary

significantly

according to body mass index (<25 vs 25 kg/m2; P for interaction, .57).

Conclusion Dietary patterns characterized by higher dairy intake, especially

low-fat dairy intake, may lower the risk of type 2 diabetes in men.

INTRODUCTION

.... The Health Professionals Follow-up Study is an ongoing longitudinal study of

51

529 male dentists, optometrists, osteopaths, pharmacists, podiatrists, and

veterinarians who were 40 to 75 years of age in 1986. The participants returned

a

mailed questionnaire in 1986 concerning diet, medical history, and medications.

We

excluded men with implausibly high (>4200 kcal/d [>17 573 kJ/d) or low (<800

kcal/d

[<3347 kJ/d]) total energy intake and/or blank responses for more than 70 of the

131

food items on the diet questionnaire. We also excluded men with a history of

diabetes, cardiovascular disease (angina, coronary bypass or angioplasty,

myocardial

infarction, or stroke), or cancer (except for nonmelanoma skin cancer) because

these

diseases affect diet or reporting of diet. After these exclusions, 41 254

participants remained in the analysis.

ASSESSMENT OF DIET

To assess dietary intake, we used a semiquantitative food-frequency

questionnaire

that inquired about the average use of approximately 130 foods and beverages

during

the previous year.16-17 The baseline dietary questionnaire was completed in 1986

and

was updated in 1990 and 1994. Nutrient intake was computed from the reported

frequency of consumption of each specified unit of food or beverage and from

published data on the nutrient content of the specified portions.17

Food and nutrient intakes assessed by this dietary questionnaire have been

validated

previously against two 1-week diet records in this cohort.16, 18 The Pearson

correlation coefficients for intake measured

.... We used proportional hazards modeling to estimate the relative risk (RR)

for

incident type 2 diabetes in all multivariate analyses (SAS Institute Inc, Cary,

NC).

Responses to the individual dairy items were converted to average daily number

of

servings of each item. The average daily intakes of individual dairy items were

combined to compute dairy intake: low-fat dairy products, including skim/lowfat

milk, sherbet, yogurt, and cottage/ricotta cheese; high-fat dairy foods,

including

whole milk, cream, sour cream, ice cream, cream cheese, and other cheese; and

all

dairy products, including all of the above. The average daily dairy intake was

categorized into quintiles of intake and each quintile was compared with the

lowest

quintile. Multivariate models were adjusted for age (continuous), total energy

intake (continuous), family history of diabetes (yes or no), smoking status

(never

smoked; former smoker; current smoker, 1-14 cigarettes per day; current smoker,

15-24 cigarettes per day; or current smoker, 25 cigarettes per day), body mass

index

(<23.0, 23.0-23.9, 24.0-24.9, 2.5-26.9, 2.7-28.9, 2.9-30.9, 31.0-34.9, or 35.0),

hypercholesterolemia at baseline (yes or no), hypertension at baseline (yes or

no),

physical activity (quintiles of metabolic equivalent tasks [METs]), cereal fiber

intake (quintiles), trans-fat intake (quintiles), ratio of polyunsaturated fat

to

saturated fat (quintiles), glycemic load (quintiles), and alcohol consumption

(0,

0.1-4.9, 5.0-14.9, 15-29.9, or 30.0 g/d). We evaluated potential confounding by

other possible dietary risk factors for type 2 diabetes (ie, nuts,1 processed

meat,22 fruits,23 vegetables,23 coffee intake,24 Western dietary pattern,25 and

prudent dietary pattern25) by entering each term (5 categories for coffee intake

and

quintiles for the others) into the multivariate model.

.... RESULTS

BASELINE CHARACTERISTICS

The baseline characteristics of the cohort according to dairy consumption levels

are

shown in Table 1. Men with higher dairy intake tended to have slightly lower

alcohol

consumption, a higher level of physical activity, a less common history of

hypertension and hypercholesterolemia, a higher intake of trans-fats, a higher

glycemic load, a lower ratio of polyunsaturated fat to saturated fat, and higher

intakes of fruits and vegetables. Other characteristics were similar across the

quintile groups (Table 1).

Table 1. Baseline Characteristics According to Dairy Food Consumption (1986)*

----------------------------------------------

Variable----Total Dairy Intake (Median Daily Servings)

---------Quintile 1 (0.5) Quintile 2 (1.1) Quintile 3 (1.6) Quintile 4 (2.3)

Quintile 5 (4.1)

------------------------------------------------------------

Age, y 53 (9) 53 (9) 53 (9) 53 (10) 53 (10)

Body mass index, kg/m 2 25.2 (3.0) 25.5 (3.1) 25.4 (3.0) 25.4 (3.1) 25.5 (3.1)

Physical activity, METs/wk 19.8 (27.4) 21.1 (31.2) 21.7 (28.1) 22.6 (31.3) 22.0

(29.3)

Current smoker, % 9 9 8 8 9

Alcohol intake, g/d 12.2 (16.4) 11.9 (15.4) 11.4 (14.8) 11.0 (14.4) 10.4 (15.0)

Family history of diabetes, % 17 17 18 18 18

Hypertension, % 21 20 20 18 17

Hypercholesterolemia, % 12 11 10 10 8

Dietary variables

Cereal fiber intake, g/d^† 5.6 (4.0) 6.0 (4.0) 6.0 (3.8) 6.0 (4.2) 5.6 (3.6)

trans-Fat intake, % of energy 2.3 (1.4) 2.6 (1.4) 2.8 (1.5) 3.1 (1.5) 3.6 (1.7)

Glycemic load 105 (45) 114 (44) 123 (44) 134 (46) 146 (49)

Polyunsaturated fat:saturated fat ratio 0.7 (0.3) 0.6 (0.2) 0.6 (0.2) 0.5 (0.2)

0.5

(0.2)

Processed meat, servings/d 0.3 (0.3) 0.3 (0.4) 0.4 (0.4) 0.4 (0.4) 0.4 (0.4)

Fruits, servings/d 2.1 (1.6) 2.2 (1.5) 2.3 (1.5) 2.5 (1.6) 2.6 (1.7)

Vegetables, servings/d 2.9 (1.7) 2.9 (1.6) 3 (1.6) 3.2 (1.7) 3.2 (1.8)

Nuts, servings/d 0.2 (0.4) 0.2 (0.4) 0.3 (0.4) 0.3 (0.4) 0.3 (0.4)

Coffee, servings/d 1.3 (1.6) 1.4 (1.6) 1.3 (1.6) 1.3 (1.6) 1.5 (1.7)

---------------------------------------------

Abbreviation: METs, metabolic equivalent tasks.

*Unless otherwise indicated, values are given as mean (SD).

^†Adjusted for total energy intake.

DAIRY PRODUCT CONSUMPTION AND INCIDENT TYPE 2 DIABETES

During the 12-year follow-up, we documented 1243 incident cases of type 2

diabetes.

After adjusting for age, the RR for men in the top quintile of total dairy

intake

was 0.82 (95% CI, 0.67-1.00; P for trend, .02) compared with those in the lowest

quintile. After further adjustment for other risk factors, the association

became

stronger (RR, 0.77; 95% CI, 0.62-0.95; P for trend, .003) (Table 2). When we

additionally adjusted for nuts, processed meat, fruits, vegetables, coffee

consumption, and dietary patterns one at a time, the results did not materially

change. Each serving-per-day increase in dairy intake was associated with a 9%

lower

risk for type 2 diabetes (multivariate RR, 0.91; 95% CI, 0.85-0.97). The

associations were essentially the same using baseline information on dairy

intake

and covariates. Furthermore, when we limited our cases to only symptomatic cases

(n

= 763), the results did not materially change.

Table 2. Relative Risk (RR) of Type 2 Diabetes Among Men According to Total

Dairy

Intake

-------------------------------------------

----------------Total Dairy Intake (Daily Servings)*

Variable---Quintile 1 (<0.9) Quintile 2 (0.9-1.3) Quintile 3 (1.4-1.9) Quintile

4

(1.9-2.9) Quintile 5 (=/>2.9)---P for Trend---RR per 1-Serving/d Increase

-------------------------------------------

No. of cases 262 272 246 220 243 . . . . . .

Person-years 89 160 92 646 90 145 89 820 90 943 . . . . . .

Age- and BMI-adjusted RR (95% CI)† 1.0 0.97 (0.81-1.16) 0.92 (0.76-1.10) 0.77

(0.64-0.93) 0.82 (0.67-1.00) .02 0.93 (0.88-0.99)

Multivariate RR (95% CI)

Unadjusted for dietary factors‡ 1.0 0.99 (0.83-1.18) 0.95 (0.80-1.15) 0.79

(0.65-0.96) 0.82 (0.67-1.00) .01 0.93 (0.87-0.98)

Adjusted for dietary factors** 1.0 0.98 (0.82-1.17) 0.92 (0.77-1.11) 0.75

(0.62-0.92) 0.77 (0.62-0.95) .003 0.91 (0.85-0.97)

Adjusted for dietary factors (baseline)** <1.0 0.96 (0.80-1.14) 0.88 (0.73-1.06)

0.76 (0.63-0.93) 0.75 (0.61-0.93) .003 0.91 (0.85-0.97)

------------------------------------------

Abbreviations: BMI, body mass index; CI, confidence interval.

*Includes all dairy foods except butter.

†Also adjusted for total energy intake.

‡Adjusted for age (in 5-year categories), total energy intake, biennial

follow-up

time (6 periods), family history of diabetes (yes/no), smoking status (never

smoked;

former smoker; current smoker, 1-14 cigarettes/d; current smoker, 15-24

cigarettes/d; or current smoker, =/>25 cigarettes/d), BMI, kg/m 2 (<23.0,

23.0-23.9,

24.0-24.9, 25.0-26.9, 27.0-28.9, 29.0-30.9, 31.0-34.9, or =/>35.0),

hypercholesterolemia (yes/no), hypertension (yes/no), physical activity

(quintiles

of metabolic equivalent tasks), and alcohol intake (0, 0.1-5.0, 5.1-14.0, 15-29,

or

=/>30.0 g/d).

**Additionally adjusted for cereal fiber intake, trans-fat intake, ratio of

polyunsaturated to saturated fat, and glycemic load (all in quintiles).

Using baseline (1986) dairy intake and covariates.

When we examined the association with dairy products stratified by their fat

contents, the significant inverse association was primarily limited to low-fat

dairy

consumption (Table 3). Most individual low-fat dairy products and ice cream

showed a

similar inverse trend but only skim milk reached statistical significance

(multivariate RR per serving, 0.90; 95% CI, 0.83-0.97) (Table 4).

Table 3. Relative Risk (RR) of Type 2 Diabetes Among Men According to Low-Fat vs

High-Fat Dairy Food Intake

-------------------------------------------

----------------Total Dairy Intake (Daily Servings)*

Variable---Quintile 1 (<0.9) Quintile 2 (0.9-1.3) Quintile 3 (1.4-1.9) Quintile

4

(1.9-2.9) Quintile 5 (=/>2.9)---P for Trend---RR per 1-Serving/d Increase

-------------------------------------------

------Low-Fat Dairy Foods*

Daily servings <0.14 0.15-0.49 0.50-0.99 1.00-1.57 >1.58 . . . . . .

Cases/person-year 291/97802 255/87243 235/85098 252/89670 201/90621 . . . . . .

Age- and BMI-adjusted RR (95% CI)† 1.0 0.97 (0.82-1.15) 0.90 (0.75-1.07) 0.95

(0.80-1.13) 0.73 (0.61-0.88) <.001 0.89 (0.83-0.95)

Multivariate RR (95% CI)‡ 1.0 1.02 (0.86-1.22) 0.96 (0.80-1.15) 1.00 (0.83-1.19)

0.73 (0.59-0.89) <.001 0.88 (0.81-0.94)

Multivariate RR (95% CI) (baseline)‡** 1.0 1.02 (0.86-1.23) 0.98 (0.81-1.18)

0.99

(0.81-1.20) 0.74 (0.60-0.91) <.001 0.88 (0.81-0.95)

------High-Fat Dairy Foods=/>

Daily servings <0.38 0.39-0.67 0.68-1.07 1.08-1.71 >1.72 . . . . . .

Cases/person-year 233/90486 239/90631 230/85175 264/95768 272/89696 . . . . . .

Age- and BMI-adjusted RR (95% CI)† 1.0 0.98 (0.82-1.18) 0.97 (0.80-1.17) 0.98

(0.81-1.18) 1.05 (0.86-1.27) .49 1.03 (0.96-1.10)

Multivariate RR (95% CI)‡ 1.0 1.00 (0.83-1.21) 0.97 (0.80-1.18) 0.96 (0.78-1.17)

0.97 (0.78-1.21) .78 0.99 (0.91-1.07)

Multivariate RR (95% CI) (baseline)‡** 1.0 0.92 (0.77-1.11) 0.87 (0.72-1.05)

0.85

(0.70-1.04) 0.82 (0.66-1.02) .12 0.94 (0.86-1.02)

----------------------------------------

Abbreviations: BMI, body mass index; CI, confidence interval.

*Skim/low-fat milk, sherbet, yogurt, and cottage/ricotta cheese.

†Also adjusted for total energy intake.

‡Adjusted for the same dietary and nondietary factors included in the

multivariate

model in Table 2 and also adjusted mutually for low-fat and high-fat dairy food

intake.

**Using baseline (1986) dairy intake and covariates.

<Whole milk, cream, sour cream, cream cheese, and other cheeses.

Table 4. Multivariate Relative Risk (RR) of Type 2 Diabetes Among Men According

to

Dairy Foods

--------------------------------------------------------

Variable---Quintile or Quartile 1---Quintile or Quartile 2---Quintile or

Quartile

3---Quintile or Quartile 4---Quintile 5-----P for Trend

-------------------------------------------------------------

Skim/Low-Fat Milk

Servings <1/mo 1/mo–1/wk 2-4/wk 5/wk–1/d =/>2/d

Cases/person-year 283/100 899 228/68 266 243/94 307 311/117 996 144/60 718

RR (95% CI)* 1.0 1.15 (0.96-1.38) 0.93 (0.78-1.12) 0.95 (0.80-1.13) 0.78

(0.63-0.97)

..007

Whole Milk