December 08, 2005
Low Carbohydrate And Low Fat Diets Compared On Cholesterol

Low carbohydrates and low fat diets produce different heart benefits.

DURHAM, N.C. -- People who followed a low-carbohydrate diet for six months raised their good cholesterol and lowered their triglycerides, changes that can help lower the risk of heart disease, Duke University Medical Center researchers found.

The Duke study compared the effects of a low-carbohydrate diet, which included nutritional supplements, with a low-fat, low-cholesterol, low-calorie diet. The two diets improved cardiac risk in different ways, said lead researcher Eric Westman, M.D., associate professor of medicine at Duke University Medical Center.

The low-carb diet improved HDL, or good cholesterol levels, and lowered triglycerides, the researchers found. The reduced fat diet lowered total cholesterol levels and triglyceride levels. Both diets brought down blood levels of small LDL particles, the form of bad cholesterol most likely to lead to hardened arteries, they found.

The results appeared early online November 16, 2005 in the International Journal of Cardiology and will appear in print in 2006. The research was funded by an unrestricted grant from the Robert C. Atkins Foundation. The study authors have no financial interest in Atkins Nutritionals, Inc.

"I think the emerging science shows different diets improve cardiac risk in different ways. We are moving from a one-size-fits-all approach to considering many different diets to fit the many different types of cardiac risk," Westman said.

Triglycerides fell much more on the low carb diet.

Overall, both diets had positive effects on cholesterol, Westman said. The triglyceride levels improved significantly in both groups, falling 74.2 points for the low-carb group and 27.9 points for the low-fat group. People on the low-carb diet showed an increase in HDL cholesterol by 5.5 points, a positive change, while those following the low-fat diet did not have a significant change. LDL cholesterol levels did not change significantly in either group but small LDL particles decreased 17.4 points for the low-carb dieters and 19.2 points for the low-fat dieters, a similar improvement. The total cholesterol of the low-fat dieters saw a 13.7 point decline over 6 months but did not change significantly in the low-carb dieters.

My guess is there is enough genetic variability in how bodies respond to different diets that one would benefit from trying different diets and then getting one's cholesterol tested.

They say the participatns were "in generally good health". But some of the participants have body mass indexes as high as 60. Er, this doesn't strike me as compatible with the "generally good health" label. Also, these people all had high cholesterol levels.

The 120 study participants were randomly assigned to either the low-carbohydrate diet or the low-fat, low-cholesterol, low-calorie diet. All were between 18 and 65 years old and in generally good health, with a body mass index (BMI) between 30 and 60, indicating obesity, and a total cholesterol level of more than 200 mg/dL. None had tried dieting or weight loss pills in the previous six months.

There's also the possibility that people who have low cholesterol levels react to low fat and low carbohydrate diets differently than do people with high cholesterol. So if you have low cholesterol yet still want to optimize your diet be aware this study might not provide useful guidance.

The low carb dieters were allowed unlimited meat and eggs. But the details matter a great deal. My guess is you'd be a lot better off eating unlimited salmon than unlimited beef and then fowl would fall somewhere in between salmon and beef in terms of health effects. But what proportion of each meat type did the dieters choose?

The low-carbohydrate group was permitted daily unlimited amounts of animal foods (meat, fowl, fish and shellfish); unlimited eggs; 4 oz. of hard cheese; two cups of salad vegetables such as lettuce, spinach or celery; and one cup of non-starchy vegetables such as broccoli, cauliflower or asparagus. They also received daily nutritional supplements -- a multivitamin; essential oils including flax seed oil, borage oil and fish oil; and chromium picolinate. There were no restrictions on total calories, but carbohydrates were kept below 20 grams per day at the start of the diet.

The low-carbohydrate diet appears to have a favorable effect on cardiac risk, Westman said. "While the low-carbohydrate group received extra nutritional supplements, and experienced greater weight loss, these differences did not fully account for the changes in cardiac risk factors that we saw," he said.

The low-fat, low-cholesterol, low-calorie group followed a diet consisting of less than 30 percent of daily caloric intake from fat; less than 10 percent of calories from saturated fat; and less than 300 milligrams of cholesterol daily. They were also advised to cut back on calories. The recommended daily calorie level was 500 to 1,000 calories less than the participant's maintenance diet -- the calories needed to maintain current weight.

The size of the cutback in fat does not seem that radical to me and falls far short of a Pritikin-style diet.

Both diets leave out junk foods.

Westman noted that the diets have one often-ignored similarity. "It's possible that the common denominator of these diets is what they're not eating both diets did not allow refined sugar or junk food," Westman said.

Study participants were encouraged to exercise 30 minutes at least three times per week, but no formal exercise program was provided. Both sets of dieters had group meetings at an outpatient research clinic regularly for six months.

I have a hard time coming to a conclusion on the debate about the ideal relative ratio of carbos to proteins to fats. Certainly the types of fats matter a great deal with differences as a function of omega 3 versus omega 6 fats and also fats of various levels of saturation. Plus, particular fatty acids might have especially harmful or healthful effects.

I'd like to see blood fat and cholesterol comparisons of diets with different types of carbs. How does a fruit diet differ from, say, a potato diet? Carb glycemic index differences cause differences in the size of blood spikes when consuming carbs and that might lead to differences in amounts of triglycerides and cholesterol. Imagine two groups ate equal amounts of rice but one group ate low glycemic index basmati rice and another ate the really sticky high glycemic index rice found at Chinese restaurants. My guess is the latter rice diet would have worse effects on blood fats and cholesterol than a basmati rice diet.

The benefit from eating a lot of fruits and vegetables seems more certain that the benefit of changing the relative proportion of fats, proteins, and carbs. Also, a number of foods have clear health risks. For example, charcoal cooked steak should be avoided. The flames and fossil fuels burning with the steak fat are a guaranteed way to produce a lot of carcinogens. Also, trans fatty acids found in many processed foods such as potato chips and many commercial cookies are definitely health unhealthy.

If you want to start improving your diet first remove the very bad foods from it while adding clear winners such as fruits and vegetables.

Share |      Randall Parker, 2005 December 08 10:10 PM  Aging Diet Studies

PacRim Jim said at December 8, 2005 10:30 PM:

Severe calorie restriction extends life. Complete calorie restriction allows one to kick the oxygen habit.

Alan Little said at December 9, 2005 3:48 AM:

Interesting article and observations generally. A found your comment on sticky rice versus basmati interesting - do you have a cite for basmati being particularly low glycemic index? I would have thought brown rice would have clear benefits over white, largely from all the fibre in the husks, but different kinds of white rice? (Anything that gave me sound health grounds to eat delicous basmati rice would be a Good Thing)

bri777 said at December 9, 2005 7:07 AM:

Just another notch in the late Dr. Atkins belt. He may not have been totally correct but let us remember, when these low carb diet studies were being started, nutritionists were expecting people to die. Okay, I exaggerate a little but their hysterics about low carb diets have not been confirmed by even one study. Even including more high fat into the diet simply raised total cholersterol, including HDL which counter-balanced the higher LDL.

Alan Little said at December 9, 2005 9:53 AM:

The obvious caveat to all the low-carb, lots of meat, supposedly "hunter-gatherer"-style diets is that our lean, fit hunter-gatherer ancestors were eating lean, fit wild animals. Factory-farmed domestic animals are anything but.

Hugh Angell said at December 9, 2005 6:31 PM:

Just finished a phase 2 clinical trial for low HDL. Important topic no doubt, but we all
can't eat salmon all the time. There is not enough to go around.

One big problem is the homogenization of our food supply. We shop at the same groceries and
we are presented with the same food supply, more or less. Shelf space is 'sold'. Kneel down
the next time you vist your grocery and walk down the 'cereal' aisle. You will see that
while your eyes are at the "Cheerios" level your children's eyes are seeing "Count Chocula"

For me, time is a constraint and, I admit, so is flavor. I cannot spend a great deal of
time preparing my meals so Stouffer's Lasagna was easy to devour. I realized that microwave
was unhealthy but if cabbage was good for me, eating it 'raw' was not a meal.

The real need is for the food industry and pharmaceutical companies to work together. We
do have an FOOD and DRUG AGENCY afterall. There is no real reason why tasty AND healthy
meals cannot be sold without an unwelcome dose of sodium or preservatives.

As to Alan Little's remark about the difference between today's meat and our ancestor's.
Perhaps there was less fat in the ancient meat but, whether raising it or hunting it, one
expended a great deal more energy putting a steak on an ancient table than one does today
going to the local steakhouse.

BTW, I think unless and until, medical and dietary studies can initiate better controls
on extraneous factors than they currently do their real value is limited.

Randall Parker said at December 9, 2005 7:42 PM:


The best source I've found on glycemic index for foods is David Mendosa's glycemic index chart. I mentioned Basmati rice precisely because I've studied Mendosa's chart in the past. Some of the other rices on his list are too generic in title to go out and find. Note that some rices have almost double Basmati's glycemic index. Some have so much amylose that they are even substantially lower than Basmati. But Basmati ends up being the lowest glycemic index rice that I can know to go look for in a store. Though some of the Uncle Ben's rices look pretty decent as well.

The different potato types vary a great deal too btw. There are some really low GI potatoes but I have no idea of the odds of finding them.

R Silvetz said at December 9, 2005 8:10 PM:

Welcome news, but misses the point.

The inflammatory state of the vasculature is much more important than cholesterol levels. E.g. patients with a low inflammatory state will not deposit cholesterol on their arterial walls, regardless of their cholesterol levels. This explains the paradox of many patients with spetacular cholesterol/triglyceride levels that present with advanced heart disease.

So get those homocysteine/C-Reactive Protein/TNF levels checked and avoid the refined sugars etc. The big insulin/glucagon swings are wonderful initiators of inflammation.

Randall Parker said at December 9, 2005 8:18 PM:

My main problem with a high meat diet is that it probably increases cancer risk. So I'm not a fan of the Atkins diet.

High homocysteine is an argument for eating legumes and beans to get a lot of folic acid. Either that or take folic acid supplements.

Inflammation as a cause of cardiovascular disease is an argument for getting plenty of omega 3 fatty acids ihn the diet.

R Silvetz said at December 9, 2005 11:11 PM:

Well, the problem with non-range meats today is their horrible fatty-acid/high arachidonic acid profile. It is this prostaglandin-induced inflammatory profile that is mostly responsible for the increased cancer risk.

This for example, is not the case with range-fed beef.

Having said that, one's homocysteine output is a side-effect of methionine metabolism, which as near as can be told is purely set at the genetic level. Thus to the extent that B6-B12, Trimethylglycine, N-acetyl-cysteine, and SAMe can deflect homocysteine they are good supplements.

The simple truth is that noone need suffer heart disease as an outcome if one is careful.

James Bowery said at December 10, 2005 9:08 AM:

I've been growing arthrospira platensis (aka spirulina) on a bench scale successfully just to get experience with it precisely due to the fact algae is the most efficient producer of protein -- between 2 and 20 times more efficient than soya beans depending on who's numbers you accept. Moreover the protein is a broad spectrum of amino acids -- one of the broadest of any source. The omega-3 content isn't high enough for biodiesel but it is more than high enough for a healthy diet. The big dietary problem with it appears to be the high nucleic acid content due to the high percentage of its mass that is DNA. I've eaten enough spirulina to get a temporary attack of gout. The simplest solution is to run the spirulina through an algae grazing fish, such as tilapia, in an aquaponics system. The trophic losses aren't as bad as they are in the wild -- possibly as little as 60%. The big production problem with it is keeping the water warm. Eventually all this algae-based stuff (food and biodiesel) will find its natural home in the ocean but until then it looks like a really good use of "waste" heat is to grow high protein algae and feed it to algae grazers.

Lou Pagnucco said at December 10, 2005 9:59 AM:

Just a couple of remarks spanning several of the above comments:

It might still be wise to avoid high fructose fruits/juices since fructose seems to accelerate plaque formation.
(So do peanuts, according to some sources, even though they have a very low GI.)

It may be worth considering supplementing diets with omega-3 oils, low dose doxycycline, low dose
aspirin (or extra salicylate-rich fruits/vegetables) and, perhaps, leukotriene blocking herbs like
boswellia to lower vascular and systemic inflammation.

Also, it may be beneficial to consume two teaspoons of vinegar (containing 5% acetic acid) before eating
carbohydrates to reduces the amplitude of the blood glucose spike. Drinking a beverage of viscous fluids
before or with meals may also help.

I recall reading somewhere that low protein dietary content, rather than high carb levels may be responsible
for lowering HDL. I do not know whether this has been confirmed.

Finally, phytosterol supplements, like beta-sitosterol, are quite inexpensive and appear to block cholesterol
uptake and synthesis and reduce levels of LDL.

PacRim Jim said at December 10, 2005 1:05 PM:

Apropos all this dietary nitpicking, if I outlive you, you were wrong. If you outlive me, I won't care.

gkq4f said at December 21, 2005 1:21 PM:

I've always been told by elders not to eat "Basmati Rice" every day. Can anyone think of any logical reason to this?

jonathan Oberman said at February 3, 2006 11:51 AM:

Sedentary and increasing obesity in the United States caused by the fatty and unhealthy eating habits,

cholesterol is becoming a major issue for Health Agencies - read more

Post a comment
Name (not anon or anonymous):
Email Address:
Remember info?

Go Read More Posts On FuturePundit
Site Traffic Info
The contents of this site are copyright