Dietary Fat and Cholesterol

Several of my recent blog posts have focused on nutrition, which is an integral part of health, wellness, and fitness.  Even if regular physical activity is the single best thing you can do for you health, in the long run dietary choices are probably more important than our exercise selection.  As John Berardi says in THIS ARTICLE from Precision Nutrition:

Research shows that with exercise alone you can expect to lose only about half a pound to one pound per month… With a program that combines both nutrition coaching and an exercise program, you can expect to lose five times more fat in the same one month period…

Yes, you should exercise.  But you must put nutrition first.

So as important physical activity is, be it a 10-minute, 5 set strength training program, an hour of hard training, Zumba, CrossFit, what have you…Your diet will make or break you, regardless of goals.  While we all have aesthetic and performance goals, the ultimate goal is health.  Rhetorical question:  If we’re sick or injured, we can’t reach our aesthetic or performance goals, can we?  Exactly.

I published a post earlier this week titled Hacking 20 Tips From the ADA.  Essentially, I took a 20 tip PDF I had downloaded from the American Dietetics Association and edited it with some of my own suggestions.  It included a lot of crossing out the words “Low fat.”  After I published the post, I received the following comment from an old classmate at the University of Delaware:

I don’t know if you remember me but I have to comment finally. I periodically read your posts about “nutrition” and you’re making me cringe! Have you met a dietitian? Where do u get off hating them so badly. These handouts are meant to be modified and who says we use them in practice anyway? And no full fat cheese is in no way healthy. Have fun with high cholesterol. I’m sure you’re great at exercise science but leave us alone!
From ,
A Concerned Registered Dietitian

Honestly, I agree with her.  Who am I to stereotype dieticians?  They serve a critical purpose in our health care industry, and provide integral services for clinical patients and non-clinical customers who are seeking medical nutritional intervention or nutritional counseling.  Clearly, an important job.  Stereotyping probably isn’t the best idea, and I’d be just as offended if someone assumed that all personal trainers carry a clip board and send their clients through a machine circuit, or if all ‘gym teachers’ just rolled out a ball.  Yes, these stereotypes exist for a reason, but they’re still wrong.  If I offended any RD’s in the process, I’m sorry.

I obviously haven’t met the approximately 51,840 registered dieticians in the ADA (72% of 72,000 members), and I am wrong to assume that they all follow the suggestions of the ADA.  Hopefully, they don’t.    I’d like to hope that the original list of 20 tips that I hacked was intended for a less-educated public, and is not used by dieticians in practice.  Yes, I still think that somewhere between your local farm and the offices in Washington, the bureaucratic side of the food industry has tainted America’s eating habits, recommended food sources, and contributed to less-than-optimal dietary recommendations.  Specifically, the notion that eating dietary fat is linked to high cholesterol.

Ready?  Game on.

We can start with a video I used in a blog post about Improving on Dietary Recommendations.  The video is a trailer for the documentary, Fat Head:

Dr. Eades said medical literature, didn’t he?  When you enter “Dietary Fat and Blood Lipids” into the Pub Med search engine, it provides 28,258 results.  When you focus on “Does Dietary Fat Raise Blood Lipid Levels“, it’s a more manageable 111 entries.

One of the first studies is titled “Effect of short-term low- and high-fat diets on low-density lipoprotein particle size in normolipidemic subjects.”  The study authors concluded that: “As compared with a low-fat diet, the cholesterol-raising effect of a high-fat diet is associated with the formation of large LDL particles after only 3 days of feeding.”  Okay, not good, right?  However, their study included a high-fat diet that was still high-carbohydrate (37% energy from fat and 50% from carbohydrates) and a low fat diet that was even higher carbohydrate (25% energy from fat and 62% from carbohydrates).  What happens when you control for carbohydrate consumption?

From: “Effects of dietary carbohydrate restriction versus low-fat diet on flow-mediated dilation.”

We previously reported that a carbohydrate-restricted diet (CRD) ameliorated many of the traditional markers associated with metabolic syndrome and cardiovascular risk compared with a low-fat diet (LFD). There remains concern how CRD affects vascular function because acute meals high in fat have been shown to impair endothelial function. Here, we extend our work and address these concerns by measuring fasting and postprandial vascular function in 40 overweight men and women with moderate hypertriacylglycerolemia who were randomly assigned to consume hypocaloric diets (approximately 1500 kcal) restricted in carbohydrate (percentage of carbohydrate-fat-protein = 12:59:28) or LFD (56:24:20). Flow-mediated dilation of the brachial artery was assessed before and after ingestion of a high-fat meal (908 kcal, 84% fat) at baseline and after 12 weeks. Compared with the LFD, the CRD resulted in a greater decrease in postprandial triacylglycerol (-47% vs -15%, P = .007), insulin (-51% vs -6%, P = .009), and lymphocyte (-12% vs -1%, P = .050) responses. Postprandial fatty acids were significantly increased by the CRD compared with the LFD (P = .033). Serum interleukin-6 increased significantly over the postprandial period; and the response was augmented in the CRD (46%) compared with the LFD (-13%) group (P = .038). After 12 weeks, peak flow-mediated dilation at 3 hours increased from 5.1% to 6.5% in the CRD group and decreased from 7.9% to 5.2% in the LFD group (P = .004). These findings show that a 12-week low-carbohydrate diet improves postprandial vascular function more than a LFD in individuals with atherogenic dyslipidemia.

From: “Limited effect of dietary saturated fat on plasma saturated fat in the context of a low carbohydrate diet.”

We recently showed that a hypocaloric carbohydrate restricted diet (CRD) had two striking effects: (1) a reduction in plasma saturated fatty acids (SFA) despite higher intake than a low fat diet, and (2) a decrease in inflammation despite a significant increase in arachidonic acid (ARA). Here we extend these findings in 8 weight stable men who were fed two 6-week CRD (12%en carbohydrate) varying in quality of fat. One CRD emphasized SFA (CRD-SFA, 86 g/d SFA) and the other, unsaturated fat (CRD-UFA, 47 g SFA/d). All foods were provided to subjects. Both CRD decreased serum triacylglycerol (TAG) and insulin, and increased LDL-C particle size. The CRD-UFA significantly decreased plasma TAG SFA (27.48 ± 2.89 mol%) compared to baseline (31.06 ± 4.26 mol%). Plasma TAG SFA, however, remained unchanged in the CRD-SFA (33.14 ± 3.49 mol%) despite a doubling in SFA intake. Both CRD significantly reduced plasma palmitoleic acid (16:1n-7) indicating decreased de novo lipogenesis. CRD-SFA significantly increased plasma phospholipid ARA content, while CRD-UFA significantly increased EPA and DHA. Urine 8-iso PGF(2α), a free radical-catalyzed product of ARA, was significantly lower than baseline following CRD-UFA (-32%). There was a significant inverse correlation between changes in urine 8-iso PGF(2α) and PL ARA on both CRD (r = -0.82 CRD-SFA; r = -0.62 CRD-UFA). These findings are consistent with the concept that dietary saturated fat is efficiently metabolized in the presence of low carbohydrate, and that a CRD results in better preservation of plasma ARA.

A study titled “Comparison of low fat and low carbohydrate diets on circulating fatty acid composition and markers of inflammation.” concluded that “…a very low carbohydrate diet resulted in profound alterations in fatty acid composition and reduced inflammation compared to a low fat diet.”

A similiar study showed that “Carbohydrate restriction has a more favorable impact on the metabolic syndrome than a low fat diet.”  “The findings provide support for unifying the disparate markers of [Metabolic Syndrome] and for the proposed intimate connection with dietary carbohydrate. The results support the use of dietary carbohydrate restriction as an effective approach to improve features of MetS and cardiovascular risk.”

Even in the absense of weight loss, a carbohydrate restricted diet has been shown to be effective for treating Type 2 Diabetes and Metabolic Syndrome: Carbohydrate restriction as the default treatment for type 2 diabetes and metabolic syndrome.

Dietary carbohydrate restriction in the treatment of diabetes and metabolic syndrome is based on an underlying principle of control of insulin secretion and the theory that insulin resistance is a response to chronic hyperglycemia and hyperinsulinemia. As such, the theory is intuitive and has substantial experimental support. It has generally been opposed by health agencies because of concern that carbohydrate will be replaced by fat, particularly saturated fat, thereby increasing the risk of cardiovascular disease as dictated by the so-called diet-heart hypothesis. Here we summarize recent data showing that, in fact, substitution of fat for carbohydrate generally improves cardiovascular risk factors. Removing the barrier of concern about dietary fat makes carbohydrate restriction a reasonable, if not the preferred method for treating type 2 diabetes and metabolic syndrome. We emphasize the ability of low carbohydrate diets to improve glycemic control, hemoglobin A1C and to reduce medication. We review evidence that such diets are effective even in the absence of weight loss.

When we consider Body composition and hormonal responses to a carbohydrate-restricted diet, we see that “a carbohydrate-restricted diet resulted in a significant reduction in fat mass and a concomitant increase in lean body mass in normal-weight men, which may be partially mediated by the reduction in circulating insulin concentrations.”

Additionally, “A diet based on restricting carbohydrates leads to spontaneous caloric reduction and subsequent improvement in emerging markers of CVD in overweight/obese men who are otherwise healthy.”  (Source.)

And just for fun, THIS study shows that “egg consumption might benefit blood cholesterol.”
Just as the literature exists to make us flee fat, there is also an impressive body of literature out there that clearly shows that saturated fat is not the dietary boogeyman.  Fortunately, I think the ADA is catching on.  THIS article from November of 2010 discusses the information presented at a symposium called “The Great Fat Debate: Is There Validity In the Age-Old Dietary Guidance?” at the American Dietetic Association’s (ADA) Food and Nutrition Conference and Expo.  Basically:

“Many Americans aim to eat low-fat foods but there is strong evidence that replacing fat with carbohydrates could be harmful to health…Recommendations to reduce saturated fat intake are largely based on the notion that high levels increase risk of cardiovascular disease, but unless saturated fat is replaced with other fats, many studies have suggested that fat reduction could increase risk of heart disease… Replacing saturated fat with carbohydrates – as has been widely recommended in the United States – is likely to raise the risk of cardiovascular disease.”

 

“If anything, the literature shows a slight advantage of the high fat diet,” he said. “The focus on fat in dietary guidelines has been a massive distraction…We should remove total fat from nutrition facts panels on the back of packs.”

He added that while the pervasive dietary guidance given to consumers has been to eat fats sparingly, to load up on starch and eat non-fat products, “the food industry quickly realized sugar was cheaper than fat and laughed all the way to the bank.”

“It was really the type of fat that was important,” he said. “If you replaced saturated fat with polyunsaturated fat there was a reduction of risk.”

“Overall dietary quality is very important for cardiovascular risk,” he said. “Saturated fats may raise LDL cholesterol but increasing levels of all fats lowers triglycerides…You can’t look at data across countries and draw conclusions. Nor can you look at animal studies or a single biomarker and draw conclusions from that.”

“Overall dietary quality.”  If the majority of the carbohydrates in our diet are from processed foods, including the pancakes, waffles and French toast recommended by the ADA in my original post, and we cut those out of our diet, we’re left with a lot of room to eat fruits and vegetables.  If we cut out the processed meat and food-like products such as bologna, hotdogs, and Spam, we reduce a whole lot of chemicals and additives as well.  If I were to write my own food rules, I’d have a simple one:

Fortunately, we have folks like Michael Pollan and Gary Taubes to write rules and books for us.  I’d suggest reading both Michael and Gary’s book lists, and thinking about your overall relationship with food to begin with.  Hopefully you eat some high-fat eggs and nuts for breakfast.

Look, it’s not about being right or wrong; nothing is absolutely correct.  There is a continuum of what is appropriate, and very frequently the most appropriate intervention is simply the one that you’re the most likely to comply with.  This goes for dietary programs, exercise programs, everything.  If cutting fat works for you; go ahead.  If you’re not going to deadlift but can walk the treadmill and use a leg press, fine.  It’s a continuum.

As for the American Dietetics Association, which recently changed their name to the Academy of Nutrition and Dietetics, we need them.  They’re an integral roll in the health care system and registered dieticians play a major roll in passing knowledge and information on to their patients, clients, and community.  As the ADA/AND cleans up it’s act, I hope that their position statements and recommendations begin to relate better to clean eating and healthy living, and less dependent on the funding of companies out to make a buck.  Stop thinking about fats, and carbohydrates, and grams of protein per body weight.  Eat your fruits and vegetables, savor that sirloin, and remember that fish are friends and food.

Boom goes the dynamite.