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Diabetes tipe 2 dan Vegan Diet

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Referensi :

http://www.veganhealth.org/articles/diabetestwo/

Summary

A series of studies have shown that a very low fat, mostly whole foods vegan diet can lower body weight, reduce blood sugar, and improve other parameters for type 2 diabetes.

A cross-sectional study of the Adventist Health Study-2 population showed vegans to have a 68% lower rate of diabetes than non-vegetarians.


Researchers affiliated with the Physicians Committee for Responsible Medicine (PCRM) have conducted a number of studies in which they measured the effects of a whole foods vegan diet on diabetes, body weight, blood lipids and glucose tolerance.

PCRM Pilot Study (1999)

The first was a pilot study of only 12 weeks and 11 participants, published in 1999.1 The study participants all had type 2 diabetes.

The study put some of them on a (very) low fat vegan diet. They could not eat added oils, sugars, or refined carbohydrates such as white bread or pasta. The diet was designed to have less than 10% of calories as fat. The control diet was designed to be less than 30% of calories as fat, and prohibited red meat but substituted fish and poultry. There was no limit on calories or portion sizes of either diet.

Despite not being required to limit calories, the vegan diet participants did reduce calories and lost weight. They also reduced fat and saturated fat, and their cholesterol and triglyceride levels went down.

The vegan dieters increased carbohydrates and fiber. Despite increasing carbohydrates, their fasting blood sugar levels went down, and their HbA1c (a measure of how much sugar has been in your blood over the previous three to four months) also went down.

The differences in medical outcomes between groups were that vegan dieters lost more weight and reduced blood sugar levels further. Many of the vegan dieters reduced or eliminated medications, while only one of the control dieters was able to. See Table 1 for more details.

Table 1. 1999 Pilot Study on People with Type 2 Diabetes
Vegan Diet Control Diet
No oils, sugars, refined carbs
< 10% fat
No red meat
< 30% fat
Ad libitum Yes Yes
Number of participants 7 4
Calories
Baseline
12 weeks
1683
1409
1430
1526
Carbohydrates (g)
Baseline
12 weeks
194
264
164
194
Fiber (g)
Baseline
12 weeks
14
26
12
20
Fat (g)
Baseline
12 weeks
64
17
50
53
Saturated fat (g)
Baseline
12 weeks
19
5
18
14
Weight (lbs)
Baseline
12 weeks
213
197sb
213
205
Fasting glucose (mmol/L)
Baseline
12 weeks
10.7
7.8 sb
9.7
8.6
HbA1c
Baseline
12 weeks
8.3%
6.9%
8.0%
7.0%
Total cholesterol (mg/dl>
Baseline
12 weeks
203
179
215
190
Triglycerides (mg/dl)
Baseline
12 weeks
188
165
203
164
Oral hypoglycemic agents 1 of 6 discontinued
3 of 6 reduced
0 of 4 reduced
Insulin 2 of 2 reduced None were taking
Blood pressure medication 2 of 5 discontinued 1 of 4 reduced
Lipid-lowering no changes no changes
sbStatistically significant effect between diet groups.

PCRM 2004-05 Study

In 2004, the researchers started a longer study (74 weeks) with more participants (99 people). This time, they compared a vegan diet to an American Diabetes Association recommended diet for people with type 2 diabetes.

In this study, the vegan diet was once again a very low fat diet; less than 10% of calories. Vegan dieters were asked to avoid fatty foods, added oils, fried products, avocados, nuts, and seeds. This time, instead of avoiding all refined grains, they were merely asked to favor low glycemic index foods (see Table 4 for an explanation of the glycemic index).

The control group was put on an American Diabetes Diet (ADA) of 15 – 20% protein, < 7% saturated fat, 60 – 70% carbohydrate and monounsaturated fats, and < 200 mg/day of cholesterol. The diets were individualized, based on body weight and plasma lipids. Those with a BMI > 25 kg/m2 (all but three) were prescribed energy deficits of 500 – 1,000 kcal.

For this article, I’ve reviewed four papers on this study:

  • Medical outcomes at 22 weeks2
  • Nutrient intakes at 22 weeks3
  • Medical outcomes and nutrient intakes at 74 weeks4
  • Acceptability of, and adherence to, the diets at 74 weeks5

Once again, the vegan group ate less calories and had significant weight loss. Intake of fiber and carbohydrate went up, while fasting blood sugar and HbA1c went down (only statistically significant for the first 22 weeks). Cholesterol and triglyceride levels also decreased, and many participants were able to reduce their diabetes medications.

The ADA diet group also made improvements in weight loss, HbA1c, total cholesterol, and medications.

Among participants in the vegan group with no changes to diabetes medications, HbA1c had fallen 1.23 at 22 wk and 0.82 by 74 wk. Among medication-stable participants in the conventional diet group, the HbA1c reduction was 0.38 at 22 wk, and 0.21 at 74 wk.

The only statistically significant differences between diet groups for medical outcomes was that vegan dieters lost more weight than did the ADA diet group. See Table 2 for more details.

Table 2. 2004 Study on People with Type 2 Diabetes
Vegan Vegan Diet Control Diet
No oils, fried foods, avocados,
nuts, or seeds.
Favor low glycemic-index foods.
<10% of energy from fat
American Diabetes Diet
2003 guidelines
Ad libitum Yes No
Number at baseline 49 50
Adherence at:
22 weeks
74 weeks
33
25
22
24
Calories
Baseline
22 weeks
74 weeks
1745
1432sw
1366sw
1844
1458sw
1422sw
Carbohydrates (g)
Baseline
22 weeks
74 weeks
202
244sb, sw
226sb, sw
210
170
165
Fiber (g)
Baseline
22 weeks
74 weeks
11
35sb, sw
22sb, sw
11
18sw
13sw
Fat (g)
Baseline
22 weeks
74 weeks
71
32sb, sw
34sb, sw
74
56
54
Saturated fat (g)
Baseline
22 weeks
74 weeks
24
7sb, sw
8sb, sw
22
16
16
BMI (kg/m2)
Baseline
22 weeks
74 weeks
33.9
31.8sb, sw
32.3sb, sw
35.9
34.3sw
34.8sw
Fasting glucose (mmol/L)
Baseline
22 weeks
74 weeks
9.1
7.1sw
8.0sw
8.9
7.0sw
8.1
HbA1c
Baseline
22 weeks
74 weeks
8.0%
7.1%sw
7.7%
7.9%
7.4%sw
7.8%
Total cholesterola (mg/dl)
Baseline
22 weeks
74 weeks
187
159sw
166sw
198
174sw
184sw
Triglycerides (mg/dl)
Baseline
22 weeks
74 weeks
148
120sw
114sw
158
133
150
Diabetes medications
22 weeks
74 weeks
43% reduced; 8% increased
35% reduced; 14% increased
26% reduced; 8% increased
20% reduced; 24% increased
aMany subjects were on lipid-lowering medications and adjusted them during the study.
sbStatistically significant effect between diet groups.
swStatistically significant effect within diet groups, from baseline to 22 weeks.

The acceptability of the vegan diet was rated about the same as the acceptability of the ADA diet. Although the participants in the vegan group rated the difficulty of preparing the foods as higher, they reported less dietary restraint, probably due not to having to limit calories or count carbohydrates. Vegan dieters’ cravings for sweets and fats also decreased.

At week 22, 67% of the vegans were adhering to the diet. By week 74, it was down to 51%. This drop in adherence was probably influence by the change in the program from weekly meetings for diet and cooking instruction, to bi-weekly optional meetings for weeks 23 to 74 .

2005 PCRM Study on Glucose & Insulin

In 2005, PCRM researchers published results from a study performed on postmenopausal women who were overweight or obese, but did not have type 2 diabetes.6 This study put half the women on a very low fat vegan diet of less than 10% calories as fat and no oils, avocados, olives, nuts, nut butters or seeds. No mention was made of refined carbohydrates or high glycemic foods. This diet was compared to a National Cholesterol Education Program (NCEP) Step II Guidelines diet, which was less than 30% fat, less than 7% saturated fat, protein about 15% of calories, and less than 200 mg/day of cholesterol.

After 14 weeks on the vegan diet, fasting glucose decreased and insulin sensitivity increased. The NCEP Step II diet did not result in such changes. Table 3 includes more results from this study.

Table 3. 2005 PCRM Study on Postmenopausal, Overweight Women.
Vegan Diet Control Diet
No oils, avocados, olives, nuts,
nut butters, or seeds.
<10% fat
NCEP Step II diet
Ad libitum Yes Yes
Number at baseline 29 30
Calories
Baseline
14 weeks
1774
1408
1762
1424
Carbohydrates (g)
Baseline
14 weeks
232
274
231
221
Fiber (g) 30 sb 21
Fat (g)
Baseline
14 weeks
62
18sb
58
31
Saturated fat (g) – 14 weeks 3sb 9
BMI (kg/m2)
Baseline
22 weeks
33.6
31.5sb
32.6
31.2
Fasting glucose (mmol/L)
Baseline
14 weeks
5.4
5.0sw
5.6
5.5
Insulin sensitivity
Baseline
14 weeks
4.6
5.7sw
4.3
4.6
sbStatistically significant effect between diet groups.
swStatistically significant effect within diet groups, from baseline to 14 weeks.

In total, these studies suggest that a very low-fat, primarily whole foods vegan diet is an appropriate diet for people with type 2 diabetes, and as effective as an American Diabetes Association diet. I want to emphasize the primarily whole foods aspect of this diet. If someone is eating a vegan diet with a lot of refined grains and sugars (including breads, white rice, and juices) they might not realize many of these benefits.

White potatoes are the one whole, plant food that might be harmful for people with type 2 diabetes if eaten in more than small amounts. White potato starch has a chemical structure that makes the sugar quickly digested and absorbed, and white potatoes produce a large glycemic load and insulin response (see Table 4).7

Table 4. Definitions
Glycemic index –
Measurement of how quickly glucose from a specific, solitary food is released into the blood.
Glycemic load –
Measurement of how much glucose from a specific, solitary food is released into the blood over the course of a certain amount of time (e.g., two hours).
Insulin load –
Measurement of how much insulin is released into the blood over a certain amount of time, in response to eating a specific food.

Glycemic index is of little use for preventing or treating chronic disease, as foods with very little sugar can have high glycemic indexes.

White pastas, on the other hand, have a low glycemic load and insulin response7 and although they are processed they might be about the same as many whole plant foods in terms of their affects on blood sugar. Spaghetti, especially if it hasn’t been overcooked, has a low glycemic and insulin load.8

Presumably, the researchers from the PCRM studies picked such a low fat vegan diet, without nuts or avocados, because they wanted to guarantee weight loss and cholesterol improvements. However, most of the research on nuts has suggested at least moderate amounts are beneficial to heart disease and weight loss.9 It seems safe to eat moderate amounts of nuts if you have type 2 diabetes, such as 1 – 2 oz per day. A 2009 study of people with type 2 diabetes showed that 30 g of walnuts per day resulted in a greater reduction in insulin levels13.

There has not been much research on avocados and their effects on diabetes or weight loss. I would suspect that small amounts, about 1/4 an avocado per day, would be beneficial both for heart disease and weight loss. A half a cup of cubed avocados has 120 calories and 5 grams of fiber which is a reasonable amount.

I have concerns about the long-term effects of a diet with less than 10% of calories from fat. Fat is important for cell membranes, nerve tissue, and aids in digestion of fat-soluble vitamins. And, of course, omega-3 fats are important. The average vegan-on-the-street eats about 27-29%10 of their calories from fat. That much is probably not necessary, but over the long-term, I personally wouldn’t go on a diet of less than 20% fat even if I had diabetes or heart disease. That doesn’t mean you have to get your fat from French fries – whole nuts, avocados, and even small amounts of olive and canola oil are probably fine, even for people with heart disease.

Vegans and the Risk of Diabetes

A 1999 report of the results of the original Adventist Health Study showed vegetarians to have about half the risk of diabetes as non-vegetarians.11 This was a 6 year prospective study and vegans were not separated from the lacto-ovo vegetarians.

I have long suspected that vegans have lower rates of diabetes, due to the report from the Adventist Health Study and the fact that vegans generally have lower BMI’s than other diet groups. Even with a diet of about 27-29% fat, vegans have lower cholesterol and triglyceride levels, body weight, and blood pressure than non-vegans; see Disease Markers.

In April 2009, the first study measuring the type 2 diabetes rates of vegans was released. It was a cross-sectional study and found vegans to have the lowest rates of type 2 diabetes of any diet group.12 Results are in Table 5.

Table 5. Cross-sectional Type 2 Diabetes rates in Adventist Health Study-2.
Vegan Lacto-ovo Vegetarian Pesco-vegetariana Semi-vegetarianb Non-vegetarian
Number 2,731 20,408 5,617 3,386 28,761
Diabetes rate ratioc .51 (.40-.66) .54 (.49-.60) .70 (.61-.80) .76 (.65-.90) 1.00
Diabetes rate ratiod .32 (.25-.41) .43 (.39-.47) .56 (.49-.64) .69 (.59-.81) 1.00
aVegetarian except for fish.
bAte meat more than once a month but less than once a week.
cAdjusted for age, gender, race, activity, education, TV watching, sleep, alcohol, and BMI.
dAdjusted for all factors above except BMI.

Vegans had a 68% lower risk of type 2 diabetes than did non-vegetarians!

One word of caution: This is only a cross-sectional study. The results could mean that a vegan diet prevents diabetes, or it could mean that people with type 2 diabetes are less likely to adopt a vegan diet – or a combination of both. It does, however, mean that vegans have lower rates of type 2 diabetes and at an impressive amount – the statistical significance is about as high as I ever see in a study of diet.

Adjusting for BMI diminished the difference between vegans and non-vegetarians to some extent. This should be expected as a high BMI is a risk for type 2 diabetes. However, a lower BMI is likely caused by a vegan diet, so this should not take anything away from the idea that the diet caused the difference.

Even after adjustment for BMI, the vegans had an advantage. The authors speculated on what else could be beneficial about a vegan diet:

“The vegan group consumed about 650 grams/day of fruits and vegetables, about one-third more than the amount consumed by non-vegetarians (data not shown). Observational evidence has shown that these dietary constituents are associated with a reduction in type 2 diabetes of about 40%. Vegetarian diets contain substantially less saturated fat than nonvegetarian diets and saturated fatty acids have been shown to reduce insulin sensitivity, though a recent review concluded that some of the data supporting this idea was flawed. The vegetarian diet typically includes foods that have a low glycemic index such as beans, legumes and nuts. We did not calculate the glycemic load of the diets. Though low glycemic response diets are associated with less type 2 diabetes, cohort studies have not consistently found a relation between dietary glycemic index or load and risk of diabetes; furthermore, whether the glycemic response causes diabetes is not established.”

Conclusion

In conclusion, it appears safe to say that:

  • A whole foods vegan diet is safe for people who have type 2 diabetes and is as beneficial, if not moreso, than a typical ADA diet.
  • Vegans have lower rates of type 2 diabetes than non-vegetarians.

Note that the participants in the PCRM studies were provided with vitamin B12 supplements. All vegans should follow the daily recommendations listed in Staying Healthy on Plant-Based Diets.


Footnotes

1. Nicholson AS, Sklar M, Barnard ND, Gore S, Sullivan R, Browning S. Toward improved management of NIDDM: A randomized, controlled, pilot intervention using a lowfat, vegetarian diet. Prev Med. 1999 Aug;29(2):87-91.

2. Barnard ND, Cohen J, Jenkins DJ, Turner-McGrievy G, Gloede L, Jaster B, Seidl K, Green AA, Talpers S. A low-fat vegan diet improves glycemic control and cardiovascular risk factors in a randomized clinical trial in individuals with type 2 diabetes. Diabetes Care. 2006 Aug;29(8):1777-83. PubMed PMID: 16873779. (Medical outcomes at 22 weeks.)

3. Turner-McGrievy GM, Barnard ND, Cohen J, Jenkins DJ, Gloede L, Green AA. Changes in nutrient intake and dietary quality among participants with type 2 diabetes following a low-fat vegan diet or a conventional diabetes diet for 22 weeks. J Am Diet Assoc. 2008 Oct;108(10):1636-45. (Nutrient intakes at 22 weeks.)

4. Barnard ND, Cohen J, Jenkins DJA, Turner-McGrievy G, Gloede L, Green A, and Ferdowsian H. A low-fat vegan diet and a conventional diabetes diet in the treatment of type 2 diabetes: a randomized, controlled, 74-wk clinical trial. Am J Clin Nutr 2009;89(suppl):1S-9S. (Medical outcomes and nutrient intakes at 74 weeks.)

5. Barnard ND, Gloede L, Cohen J, Jenkins DJ, Turner-McGrievy G, Green AA, Ferdowsian H. A low-fat vegan diet elicits greater macronutrient changes, but is comparable in adherence and acceptability, compared with a more conventional diabetes diet among individuals with type 2 diabetes. J Am Diet Assoc. 2009 Feb;109(2):263-72. (Acceptability and adherence at 74 weeks.)

6. Barnard ND, Scialli AR, Turner-McGrievy G, Lanou AJ, Glass J. The effects of a low-fat, plant-based dietary intervention on body weight, metabolism, and insulin sensitivity. Am J Med. 2005 Sep;118(9):991-7.

7. Holt SH, Miller JC, Petocz P. An insulin index of foods: the insulin demand generated by 1000-kJ portions of common foods. Am J Clin Nutr. 1997 Nov;66(5):1264-76. PubMed PMID: 9356547.

8. Foster-Powell K, Miller JB. International tables of glycemic index. Am J Clin Nutr. 1995 Oct;62(4):871S-890S. Review.

9. Mattes RD, Kris-Etherton PM, Foster GD. Impact of peanuts and tree nuts on body weight and healthy weight loss in adults. J Nutr. 2008 Sep;138(9):1741S-1745S. (Asbstract)

10. Davey GK, Spencer EA, Appleby PN, Allen NE, Knox KH, Key TJ. EPIC-Oxford: lifestyle characteristics and nutrient intakes in a cohort of 33 883 meat-eaters and 31 546 non meat-eaters in the UK. Public Health Nutr. 2003 May;6(3):259-69.

11. Fraser GE. Associations between diet and cancer, ischemic heart disease, and all-cause mortality in non-Hispanic white California Seventh-day Adventists. Am J Clin Nutr. 1999 Sep;70(3 Suppl):532S-538S.

12. Tonstad S, Butler T, Yan R, Fraser GE. Type of Vegetarian Diet, Body Weight and Prevalence of Type 2 Diabetes. Diabetes Care. 2009 Apr 7. [Epub ahead of print]

13. Tapsell LC, Batterham MJ, Teuss G, Tan SY, Dalton S, Quick CJ, Gillen LJ, Charlton KE. Long-term effects of increased dietary polyunsaturated fat from walnuts on metabolic parameters in type II diabetes. Eur J Clin Nutr. 2009 Aug;63(8):1008-15. Epub 2009 Apr 8. PubMed PMID: 19352378.

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Author: apotekmiami-drsatyadeng

I. Dokter Umum II. Akupunktur Medik III. Skin & Slimming Care IV. Program Pencegahan & Pemulihan Penyakit V. Lymphedema Center Indonesia VI. Catering Pencegah Penyakit VII. PIRT Kesehatan Vegan Kuartet Nabati

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