Wednesday, 6 February 2013

Durian and Cholesterol

The Cholesterol Content of Durian

Is durian high in cholesterol? No. This part is simple: durian does not contain cholesterol. None at all. The USDA National Nutrient Database lists any amount of durian as containing 0.0 mg of cholesterol. For those familiar with basic nutrition or biology this should come as no surprise since no plants contain cholesterol. So, durian doesn't have any cholesterol and neither does any other fruit or vegetable.

Dietary Fat Influences Cholesterol Levels

Durian is not off the hook just yet, though, because even without containing cholesterol food can affect a person's blood cholesterol levels. Dietary fat has an influence on the amount and type of cholesterol circulating in our arteries. The scientific community has conflicting opinions on the details of this relationship, but the majority of evidence seems to indicate that increased dietary fat intake results in increased blood cholesterol levels (within a range).

Durian, with an average of 30 percent of calories coming from fat, is a fatty fruit, but does eating it increase your fat intake (and therefore your cholesterol)?  The answer is 'yes' if the alternative is a handful of bananas, plain rice, or a plain potato, but more common meals like fried rice with chicken, a baked potato with butter, or macaroni and cheese, are all likely to contain more fat per serving than durian. For comparison, 72 percent of calories in cheddar cheese are from fat and even a glass of 2% reduced fat milk provides 35 percent of its calories from fat.

Not that all of this fat is necessarily a bad thing. Cholesterol is vital to good health. While you don't want your cholesterol levels to be too high, extremely low cholesterol leads to its own set of problems. Eating a moderate amount of fat can help to keep your cholesterol in the healthy range, between 160 and 200 mg/dL.
Total blood cholesterol is, however, only part of the story. Perhaps more important for cardiovascular health are the amounts of high density lipoprotein (HDL) and low density lipoprotein (LDL) circulating in your blood. HDL is known as 'good' cholesterol, and LDL is commonly regarded as 'bad.' Most people with cholesterol issues will benefit from lowering LDL and increasing HDL. How do you do that?

Improving Cholesterol Levels

Here's the mainstream medical advice for achieving healthy cholesterol levels:
  • Exerise regularly – Opening a durian is exercise.
  • Maintain a healthy weight – Skip the all-you-can-eat durian buffet?
  • Avoid trans fats – Not a problem. Don't deep fry your durian.
  • Limit saturated fats  – Unfortunately, this one might apply.
Most medical and public health literature advises us to limit our consumption of fats and especially of saturated fats which are accused of causing a rise in total cholesterol. My research into the relationship between dietary saturated fat and cholesterol levels has not lead me to easy conclusions. It is a complicated subject, and one on which many disagree. I will attempt to paint a picture of the complexities while respecting the prevailing precautionary recommendation.

It is worth considering the difficulty of establishing the relationship between serum cholesterol and any one nutrient. To reduce saturated fat intake without reducing total calories requires increasing some other nutrient, so it is not possible to claim that limiting saturated fats reduces serum cholesterol without considering the substitute (or otherwise showing the effect wasn't the result of reduced total calories).

A meta-analysis of 60 controlled trials found that replacing saturated fats with carbohydrates did little to improve the total to HDL ratio, while replacing saturated fat with unsaturated fats (cis, of course, not trans) did show significant improvements. 

The same study also found that while lauric acid, a saturated fat, increased total cholesterol, it achieved this mostly through an increase of HDL, the 'good' cholesterol. Lauric acid is not especially prevalent in durian, but this finding does suggest the current stance against saturated fat deserves further consideration.

The standard advice shouldn't be casually disregarded, but there is a growing field of researchers who disagree with the commonly held belief that saturated fat causes unhealthy cholesterol levels. These thinkers also tend to question the causal relationship between cholesterol levels and heart disease, citing the greater positive correlation of other conditions such as inflammation. If you want to learn a great deal more, consider my recommended reading list below.

Until the evidence is sufficient to persuade the majority to rewrite the books, it may be prudent to limit most dietary saturated fats and when necessary reduce their intake by substituting with monounsaturated and polyunsaturated fats. With that in mind, let's take a look at the saturated fat content of durian and how the king of fruits can fit into a healthy diet.

The Fat of the Matter

The fatty acid composition of durian is different for each variety, but there are enough similarities to draw a general picture. The USDA lacks detailed data on the breakdown of durian's fat, but an independent study analyzing the fatty acid content of four Malaysian cultivars (D-24, D-2, D-8, D-66) found a fair amount of saturated fat, between 58 and 65 percent of total fat (Berry, 1981).

That's high compared to well-known sources of monounsaturated fat like olive oil, which is only 14 percent saturated, and almonds (7%), but still lower than butter (68%), and coconut oil (86%). Of course, only 5 percent of a durian is fat; almonds are 49 percent, butter 51 percent, and olive oil and coconut oil are 100 percent fat. Point being you can eat considerably more (10 to 20 times more!) durian and consume the same amount of saturated fat found in a lesser amount of these higher fat foods.
The American Heart Association recommends limiting saturated fat to 7 percent of daily calories. The USDA Center for Nutrition Policy and Promotion suggests limiting saturated fat to 10 percent of daily calories. On a 2000 calorie diet, 7 percent allows 16 grams, and 10 percent allows 22 grams of saturated fat. To reach 16 grams you would have to eat about 450 grams of durian. Monthong, one of the fleshiest durians, is 30 percent edible. If we use that figure (which is on the high end to be safe), we will find 450 edible grams in a 1.5 kg durian. The 10% mark of 22 grams saturated fat is found in 2.0kg of durian, by this same estimation.

Conclusions

Luckily, it seems the recommendations for achieving healthy cholesterol levels do not preclude eating durian. They may, however, indicate moderation of durian consumption is wise for people with existing cholesterol issues. For the rest of us, I think it is probably safe to pig out.

If your diet is otherwise low in saturated fat, you can safely eat a 1.5 to 2.0 kilogram durian, even the fleshiest varieties with the highest saturated fat, every single day and fall within the guidelines for a heart healthy diet.
References:
  1. U.S. Department of Agriculture, Agricultural Research Service, USDA Nutrient Data Laboratory. 2008. USDA National Nutrient Database for Standard Reference, Release 21. 
  2. "Fats and Cholesterol: Out with the Bad, In with the Good." The Nutrition Source. Harvard School of Public Health. Web.
  3. Mensink, Zock, Kester, Katan. "Effects of dietary fatty acids and carbohydrates on the ratio of serum total to HDL cholesterol and on serum lipids and apolipoproteins: a meta-analysis of 60 controlled trials." American Journal of Clinical Nutrition 77.5 (2003): 1146-1155.
  4. Brown, Michael J. Durio - A Bibliographic Review. Ed. R.K. Arora, V. Ramanatha Rao and A.N. Rao. New Delhi: IPGRI office for South Asia, 1997. Print.
  5. Berry, Shiv. "Fatty acid composition and organoleptic quality of four clones of durian (Durio zibethinus, murr.)." Journal of the American Oil Chemists' Society 58.6 (1981): 716-717. DOI: 10.1007/BF02899460
  6. American Heart Association. "Know Your Fats." Published online. Updated June 25, 2012.
  7. USDA Center for Nutrition Policy and Promotion. Dietary Guidelines for Americans, 2010. Print and Web.
Recommended Reading (Alternative Opinions on Saturated Fat):
  1. Stephen Guyenet's article on the effect of long-term saturated fat intake on blood cholesterol levels is a good introductory read.
  2. Gary Taube's Good Calories, Bad Calories is a critical look at the history and evolution of nutritional and health sciences politics that lead to the current “fat is bad” paradigm.
Disclaimer: This article is for general education purposes only and should not be regarded as medical advice. If you have a cholesterol condition consult a licensed physician.

1 comment:

  1. This article was copied/stolen from http://www.yearofthedurian.com/2012/08/durian-and-cholesterol.html

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