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US Government Poised to Drop Cholesterol Warnings? | The Paleo DietCholesterol – is there a more controversial topic in the world of nutrition? For years, we were told that cholesterol is one of the most important biomarkers of health, particularly cardiovascular health. Prominent government- and health-related institutions have traditionally recommended upper limits on dietary cholesterol of 300 mg/day (effectively limiting egg consumption to 1 egg per day.) A recommendation based on the theory that dietary cholesterol – the cholesterol contained in food – negatively impacts cholesterol found in the blood, called serum cholesterol.

With the emergence of more and more scientific evidence, however, this theory has become increasingly untenable, causing many scientists to change their views on cholesterol. The counter theory – that dietary cholesterol has little impact on serum cholesterol – is actually nothing new. Even the progenitor of the misguided lipid theory of heart disease, Ancel Keys, acknowledged back in 1953 that dietary cholesterol doesn’t significantly impact serum cholesterol.1

Unfortunately, cholesterol came to be demonized due to its association with saturated fat and for decades both were thought to be unhealthy. New studies in the past several years have challenged this orthodox view of cholesterol.

The new research has also challenged traditional beliefs about eggs. Rather than limiting egg consumption, the available evidence suggests that eggs are actually cardio-protective.

In March 2017, for example, The Journal of Nutrition published a new study about egg consumption and its positive effects on both HDL function and plasma antioxidant levels.2 Previous studies had shown similar benefits, but those studies were largely conducted on unhealthy populations.3,4,5

The authors of this new study, therefore, decided to test how eating one, two, or three eggs daily would affect healthy young adults. This study was the latest in a series of scientific papers showing that foods rich in dietary cholesterol can actually decrease one’s risk for heart disease – a complete turnaround from the institutional forebodings of decades past.

 

Important, But Not Essential

Cholesterol is not an essential nutrient. This means that although your body requires cholesterol, you’re not dependent on food to obtain it. In fact, your liver produces 90% of the cholesterol needed by your body. Some people use this fact to advance the hypothesis that dietary cholesterol is unnecessary or even unhealthy. This hypothesis is flawed for several reasons, including:

  1. The foods that contain significant amounts of cholesterol also contain many other important nutrients, particularly iron, and vitamin B12.
  2. Nearly all foods that contain bioavailable forms of high-quality protein also contain cholesterol.

 

The Origins of the Theory

So where does the idea that dietary cholesterol is unhealthy come from? Surprisingly, the early studies that inspired this idea were actually conducted on rabbits. While this may seem reasonable, it’s important to remember that rabbits are herbivores. And since their natural diets don’t contain cholesterol, it’s no surprise that it impacts them negatively.

Nikolay Anichkov was the scientist who originally conducted these rabbit studies back in the early 20th century. Interestingly, he fed rabbits a purified form of cholesterol.6 Obtaining cholesterol this way is completely different from obtaining cholesterol from healthy foods. In fact, most of Anichkov’s peers questioned the relevance to human health of his cholesterol experiments performed on rabbits.

Nearly 40 years later, John Gofman became the next major researcher to show interest in the topic. Gofman reported that higher levels of LDL were associated with an increased risk for coronary heart disease (CHD), whereas higher levels of HDL appeared to protect against CHD.7

After Gofman, Ancel Keys became the most prominent heart disease researcher. Through a series of experiments, Keys concluded that saturated fat consumption has the biggest impact on serum cholesterol levels. However, regarding dietary cholesterol, as mentioned above, Keys reported, “repeated careful dietary surveys on large numbers of persons in whom blood cholesterol was measured consistently fail to disclose a relationship between the cholesterol in the diet and in the serum.”8

Keys became known as the father of the lipid hypothesis – the theory that fat consumption, particularly saturated fat, drives heart disease. During the past 15 years or so, the lipid hypothesis has faced serious challenges. One of its core tenets is that saturated fat increase LDL cholesterol, which does in fact correlate with heart disease. However, LDL varies by particle size – small or large.

 

Small versus Large

Small particle LDL is more prone to oxidation and to the formation of subsequent arterial lesions and arterial plaque.9 Large particle LDL is less susceptible to such modifications and therefore carries little, if any, cardiovascular risk. In fact, a study that tracked women for 11 years found no significant association between large particle LDL and cardiovascular disease risk (CVD).10

So how does all this relate to eggs and their relatively high amounts of dietary cholesterol? Some interesting findings emerged from the recent Journal of Nutrition study.2 For example, as egg consumption increased, small LDL decreased and large LDL increased – a win-win with respect to reducing CVD risk. Additionally, concentrations of HDL and the antioxidants lutein and zeaxanthin also increased as daily egg consumption went up.2

One great benefit of HDL is its ability to remove cholesterol from macrophages. This is one of the key aspects of preventing the build-up of cholesterol inside the blood vessels. Additionally, this is one reason why low HDL is related to increased CVD risk.11

 

Conclusions

Eggs have gotten a bad rap, mostly due their high levels of cholesterol and due to our imprecise, yet ever-evolving, views on the relationship between cholesterol-rich foods and blood cholesterol levels.

Unfortunately, the nutrition establishment is still struggling to acknowledge the obvious – that eggs and other cholesterol-rich foods are healthy. Back in 2015, the USDA was in the process of updating its official Dietary Guidelines for Americans. In its Preliminary Report, published in February 2015, the group’s Advisory Committee recommended dropping the decades old 300 mg/day limit on dietary cholesterol. The available evidence, they reported, “shows no appreciable relationship between consumption of dietary cholesterol and serum cholesterol.”12 Accordingly the committee concluded, “cholesterol is not a nutrient of concern for over-consumption.”

Unfortunately, as soon as the clouds of bad conclusions dissipated, they quickly reemerged, again blocking the light of reason and evidence. For in their final report, published in January 2016, the USDA backed away from the Preliminary Report’s encouraging conclusions. Instead, they settled on “individuals should eat as little dietary cholesterol as possible while consuming a healthy eating pattern.”13

So we’re back to square one. The usual suspects are still warning against dietary cholesterol, whereas the scientific evidence draws other conclusions. Egg-white omelets are still served in many restaurants, whereas the nutrient-rich yolks are often discarded. Are eggs healthy? The science says yes, but you can decide.

 

References

[1] Keys, A. (1953). Prediction and Possible Prevention of Coronary Disease. Am J Public Health Nations Health., 43(11). Retrieved from (link).

[2] DiMarco DM, et al. (2017). Intake of up to 3 Eggs per Day Is Associated with Changes in HDL Function and Increased Plasma Antioxidants in Healthy, Young Adults. Journal of Nutrition, 147(3). Retrieved from (link).

[3] Herron KL, et al. (2004). High intake of cholesterol results in less atherogenic low-density lipoprotein particles in men and women independent of response classification. Metabolism, 53(6). Retrieved from (link).

[4] Mutungi G, et al. (2008). Dietary Cholesterol from Eggs Increases Plasma HDL Cholesterol in Overweight Men Consuming a Carbohydrate-Restricted Diet. Journal of Nutrition, 138(2). Retrieved from (link).

[5] Blesso CN, et al. (2013). Whole egg consumption improves lipoprotein profiles and insulin sensitivity to a greater extent than yolk-free egg substitute in individuals with metabolic syndrome. Metabolism, 62(3). Retrieved from (link).

[6] Finking G, et al. (1997). Nikolaj Nikolajewitsch Anitschkow (1885-1964) established the cholesterol-fed rabbit as a model for atherosclerosis research. Atherosclerosis, 135(1). Retrieved from (link).

[7] Gotto AM, et al. (2011). Jeremiah Metzger Lecture: Cholesterol, Inflammation and Atherosclerotic Cardiovascular Disease: Is It All LDL? Trans Am Clin Climatol Assoc., 122. Retrieved from (link).

[8] Keys, A. (1953). Prediction and Possible Prevention of Coronary Disease. Am J Public Health Nations Health., 43(11). Retrieved from (link).

[9] Ross R. (1999). Atherosclerosis – an inflammatory disease. New England Journal of Medicine, 340(2). Retrieved from (link).

[10] Mora S, et al. (Feb 2009). Lipoprotein particle profiles by nuclear magnetic resonance compared with standard lipids and apolipoproteins in predicting incident cardiovascular disease in women. Circulation, 119(7). Retrieved from (link).

[11] Assmann G, et al. (1996). High-density lipoprotein cholesterol as a predictor of coronary heart disease risk. The PROCAM experience and pathophysiological implications for reverse cholesterol transport. Atherosclerosis, 124. Retrieved from (link).

[12] 2015 Dietary Guidelines Advisory Committee. (Feb 2015). Scientific Report of the 2015 Dietary Guidelines Advisory Committee. US Department of Health and Human Services and US Department of Agriculture. Retrieved from (link).

[13] USDA. (2016). Dietary Guidelines for Americans, Final Report. Retrieved from (link).

Cholesterol | The Paleo Diet

Dr. Kim A. Williams, the President-Elect of the American College of Cardiology, recently published an essay, “Vegan Diet, Healthy Heart?” which has sparked passionate debate.1 “I didn’t know it would create such a firestorm of everything from accolades to protests,” said Williams.2 His essay describes how his LDL cholesterol level dropped from 170 to 90 within six weeks of adopting a vegan diet. He now encourages patients with diabetes, hypertension, coronary artery disease, and high cholesterol to consider going vegan.

By now, most people recognize the distinction between HDL, the so-called “good cholesterol,” and LDL, “bad cholesterol.” The distinction regarding LDL particle size, however, is just as important, but not universally known. LDL varies by particle size—small and large—and only small particle LDL should be labeled “bad.” Small, dense LDL particles tend to accumulate within the arteries, contributing to arterial plaque.3 Conversely, large, buoyant LDL particles float through the bloodstream and are far less likely to accumulate. Observational studies suggest small-particle LDL predicts heart disease at more than three times the rate of large-particle LDL.4

Neither William’s essay nor the response published in The New York Timesmentioned anything about this important distinction between small and large particle LDL. Most healthy individuals have predominantly higher proportions of large-particle LDL and for these people diets lower in carbohydrates and higher in fat have been shown to promote healthier blood cholesterol levels.5 Some people, however, are genetically predisposed to a phenotype characterized by a predominance of small-particle LDL and for these people diets lower in fat and higher in carbohydrates may promote healthier blood cholesterol levels.6

The Paleo Diet, of course, includes animal foods, some of which contain significant amounts of saturated fat. Dr. Williams stops short of recommending vegan diets for everyone, but readers of his essay might wrongly suppose the Paleo Diet promotes unhealthy blood cholesterol levels and that vegan diets, which are typically lower in saturated fat and higher in carbohydrates, are healthier. This might be true if not for the fact that size does matter regarding LDL—and bigger is better. Research shows that dietary carbohydrates, particularly simple sugars and starches with high glycemic indexes, increase small-particle LDL.7 From a cholesterol perspective, these are the foods to avoid. Saturated fat, on the other hand, increases only large-particle LDL, which is benign.8

And what about Paleo foods like eggs, which contain higher amounts of dietary cholesterol? Dr. Williams wrote about switching to a “cholesterol-free” vegan diet, implying that dietary cholesterol negatively impacts blood cholesterol. The scientific literature, however, doesn’t support this implication. Clinical studies show dietary cholesterol actually reduces small-particle LDL and only increases large-particle LDL, the benign variety, while also increasing HDL, thus promoting proper LDL/HDL ratios.9 Furthermore, according to a recent review, “current epidemiologic data have clearly demonstrated that increasing concentrations of dietary cholesterol are not correlated with increased risk for cardiovascular disease.”sup>10 There’s no reason, therefore, to forgo animal foods. The Paleo Diet naturally promotes healthy blood cholesterol levels.

Christopher James Clark, B.B.A.
@nutrigrail
Nutritional Grail
www.ChristopherJamesClark.com

Christopher James Clark | The Paleo Diet TeamChristopher James Clark, B.B.A. is an award-winning writer, consultant, and chef with specialized knowledge in nutritional science and healing cuisine. He has a Business Administration degree from the University of Michigan and formerly worked as a revenue management analyst for a Fortune 100 company. For the past decade-plus, he has been designing menus, recipes, and food concepts for restaurants and spas, coaching private clients, teaching cooking workshops worldwide, and managing the kitchen for a renowned Greek yoga resort. Clark is the author of the critically acclaimed, award-winning book, Nutritional Grail.

References

1. Williams, Kim. (July 21, 2014). CardioBuzz: Vegan Diet, Healthy Heart? MedPage Today. Retrieved August 8, 2014.

2. O’Connor, Anahad. (August 6, 2014) Advice From a Vegan Cardiologist. The New York Times. Retrieved August 8, 2014.

3. Voros, S., et al. (November 2013). Apoprotein B, small-dense LDL and impaired HDL remodeling is associated with larger plaque burden and more noncalcified plaque as assessed by coronary CT angiography and intravascular ultrasound with radiofrequency backscatter: results from the ATLANTA I study. Journal of the American Heart Association, 2(6). Retrieved August 8, 2014 from http://www.ncbi.nlm.nih.gov/pubmed/24252842

4. Lamarche, B., et al. (January 1997). Small, dense low-density lipoprotein particles as a predictor of the risk of ischemic heart disease in men. Prospective results from the Québec Cardiovascular Study. Circulation, 95(1). Retrieved August 8, 2014 from http://www.ncbi.nlm.nih.gov/pubmed/8994419

5. Krauss, RM. (February 2001). Atherogenic lipoprotein phenotype and diet-gene interactions. Journal of Nutrition, 131(2). Retrieved August 8, 2014 from http://www.ncbi.nlm.nih.gov/pubmed/11160558

6. Ibid.

7. Siri, PW., et al. (November 2005). Influence of dietary carbohydrate and fat on LDL and HDL particle distributions. Current Artherosclerosis Reports, 7(6). Retrieved August 8, 2014 from http://www.ncbi.nlm.nih.gov/pubmed/16256003

8. Dreon, DM., et al. (May 1998). Change in dietary saturated fat intake is correlated with change in mass of large low-density-lipoprotein particles in men. American Journal of Clinical Nutrition, 67(5). Retrieved August 8, 2014 from http://ajcn.nutrition.org/content/67/5/828.short

9. Fernandez, ML., Calle, M. (November 2010). Revisiting dietary cholesterol recommendations: does the evidence support a limit of 300 mg/d? Current Artherosclerosis Reports 12(6). Retrieved August 8, 2014 from http://www.ncbi.nlm.nih.gov/pubmed/20683785

10. Ibid.

Verdict on Monounsaturated Fats | The Paleo Diet

If SFA (saturated fatty acids) are bad for us then why does our body store excess calories that way?

Saturated fat consumption was likely unrestricted among ancient hunter gatherer populations. For the purpose of efficiency and conservation, entire animals would be consumed.

The USDA and other major government nutrition advocates claim that excess saturated fat intake will lead to exceedingly high cholesterol levels and coinciding health problems. Currently, there are no confirmed studies demonstrating the correlation of increased saturated fat intake with a higher risk for cardiovascular mortality. Saturated fat intake might increase LDL cholesterol initially, but it produces protective HDL cholesterol simultaneously.

The Inuit people of North America subsist on a diet that is extremely high in saturated fats, and the majority of the population does not exhibit cardiovascular diseases. The body does indeed store excess carbohydrates as saturated fat, but this is simply for the purpose of future energy expenditure. Saturated fat should not be feared, and is a vital fatty acid for maintaining consistent energy levels while following a Paleo lifestyle.

Bottom line: Saturated fats should be consumed in moderation along with other leaner cuts of meat.

Kyle Cordain
The Paleo Diet Team

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