Is eating too much cholesterol bad?

Question

I've been researching cholesterol a bit (my grandma is telling me off) and I've found some sites saying that eating cholesterol is not bad since you're body makes 75% of the cholesterol found in your body. That only 20-25% of the cholesterol in your body comes from food and that if you eat more, your body will cut down on its production of cholesterol.

However given that, would it be safe to say that that is only true if you don't eat more than 4 or 5 times the 'normal' amount of cholesterol? Since all the cholesterol is being provided for by food and your body is already not making any.

or if you eat over 100% does your body remove the additional cholesterol?

Basically my question is: is eating too much cholesterol bad for you?

Answer 1

The current outlook is: Dietary cholesterol is largely a non-issue still overburdened with much anxiety and even hysteria. While certain levels and ratios of "blood cholesterol" (different lipoproteins, triglycerides etc.) are still treated as indicators of possible trouble that may call for intervention, that intervention is likely pharmacological in nature and less through dietary means of reducing cholesterol intake. Dietary cholesterol is not "The Bad Guy" to avoid at all costs.

So, no, eating (too much) cholesterol is not that bad in itself. (But keep in mind that 'eating too much cholesterol' may be the result of eating too much and too fat in general. That is bad.) The type of natural fat ingested is less important over-all and even blood cholesterol or lipo-proteins are under fire as being much less of a value in predicting health outcomes or even being a worthy target to intervene at all: People with high cholesterol live the longest. And that might almost explain why decreasing cholesterol intake leads to an increase in the absorption rate and an increase in cholesterol synthesis.

Jean-Michel Lecerf and Michel de Lorgeril: "Dietary cholesterol: from physiology to cardiovascular risk", British Journal of Nutrition, Volume 106, Issue 1, 14 July 2011, pp. 6-14, https://doi.org/10.1017/S0007114511000237:

Dietary cholesterol comes exclusively from animal sources, thus it is naturally present in our diet and tissues. It is an important component of cell membranes and a precursor of bile acids, steroid hormones and vitamin D. Contrary to phytosterols (originated from plants), cholesterol is synthesised in the human body in order to maintain a stable pool when dietary intake is low. Given the necessity for cholesterol, very effective intestinal uptake mechanisms and enterohepatic bile acid and cholesterol reabsorption cycles exist; conversely, phytosterols are poorly absorbed and, indeed, rapidly excreted. Dietary cholesterol content does not significantly influence plasma cholesterol values, which are regulated by different genetic and nutritional factors that influence cholesterol absorption or synthesis. Some subjects are hyper-absorbers and others are hyper-responders, which implies new therapeutic issues. Epidemiological data do not support a link between dietary cholesterol and CVD. Recent biological data concerning the effect of dietary cholesterol on LDL receptor-related protein may explain the complexity of the effect of cholesterol on CVD risk. [emphasis added]

Mitchell M. Kanter, et al.: "Exploring the Factors That Affect Blood Cholesterol and Heart Disease Risk: Is Dietary Cholesterol as Bad for You as History Leads Us to Believe?", Advances in Nutrition, September 2012, vol. 3: 711-717, doi: 10.3945/​an.111.001321:

For much of the past 50 years, a great deal of the scientific literature regarding dietary fat and cholesterol intake has indicated a strong positive correlation with heart disease. In recent years, however, there have been a number of epidemiological studies that did not support a relationship between cholesterol intake and cardiovascular disease. Further, a number of recent clinical trials that looked at the effects of long-term egg consumption (as a vehicle for dietary cholesterol) reported no negative impact on various indices of cardiovascular health and disease. Coupled with data indicating that the impact of lowering dietary cholesterol intake on serum LDL levels is small compared with other dietary and lifestyle factors, there is a need to consider how otherwise healthy foods can be incorporated in the diet to meet current dietary cholesterol recommendations. Because eggs are a healthful food, it is particularly important that sensible strategies be recommended for inclusions of eggs in a healthy diet.

Samantha Berger et al.: "Dietary cholesterol and cardiovascular disease: a systematic review and meta-analysis", American Journal of Clinical Nutrition, 102: 235-236; July 15, 2015, doi: 10.3945/​ajcn.114.100305:

Forty studies (17 cohorts in 19 publications with 361,923 subjects and 19 trials in 21 publications with 632 subjects) published between 1979 and 2013 were eligible for review. […] Dietary cholesterol was not statistically significantly associated with any coronary artery disease […] or hemorrhagic stroke. […] Dietary cholesterol did not statistically significantly change serum triglycerides or very-low-density lipoprotein concentrations. Reviewed studies were heterogeneous and lacked the methodologic rigor to draw any conclusions regarding the effects of dietary cholesterol on CVD risk. Carefully adjusted and well-conducted cohort studies would be useful to identify the relative effects of dietary cholesterol on CVD risk.

Erik Rifkin, Edward Bouwery: "The Illusion of Certainty [Health Benefits and Risks]", Springer, New York, 2007, chap 8: "Elevated Cholesterol: A Primary Risk Factor for Heart Disease?", p. 91:

But let’s assume for a moment that Fig. 8.1 is correct. Let’s say the gentle upward trend from the lowest to the highest cholesterol level is legitimate. Let’s forget about difficulties in excluding diabetics and people with genetic abnormalities, and in normalizing for age and unknown additive or synergistic effects of multiple risk factors. Then in a group of 1,000 individuals with elevated cholesterol, there will be approximately 1 additional death annually when compared to 1,000 individuals with normal cholesterol. Therefore, 99.9% of the individuals with elevated cholesterol would not be affected. [emphasis added]

That is important: just assuming the hypothesis once taken for granted: "eating eggs clogs your arteries" (the so called "diet-heart hypothesis") is correct does not translate well into statistical observations for the general population or public health.

To give an outdated but relatable picture to this statistical figure: "1987 wies S. Seely nach, daß eine lebenslang durchgehaltene cholesterinarme Kost die Lebensdauer lediglich um drei Tage bis drei Monate, bestenfalls jedoch um ein Jahr erhöhe." (Translation: Seely had proven in 1987 that lifelong avoidance of dietary cholesterol would lead to prolongation of a life by just 3 days to 3 months overall, but one year at the most. Cited from: Werner E. Gerabek, Bernhard D. Haage, Gundolf Keil and Wolfgang Wegner: "Enzyklopädie der Medizingeschichte", Walter de Gruyter: Berlin, New York, 2007, p. 282. Note that these calculations are now viewed as likely even much less pronounced.)

A. Stewart Truswell: "Cholesterol and Beyond. The Research on Diet and Coronary Heart Disease 1900–2000", Springer: Dordrecht, Heidelberg, 2010, p. 158/9:

[citing: Dietary Prescription to Reduce the Risk of CHD from “ABC of Nutrition”, 3rd Edition (1999) [840] slightly outdated now, cited here for illustration of how outdated some advice to reduce dietary cholesterol is:]

• Total fat. Reduction is not essential for improving plasma lipids but should reduce coagulation factors and day-time plasma triglycerides and contribute to weight reduction.
• Saturated fatty acids. Principally 14:0, 16:0 and 12:0 should be substantially reduced from around 15% of dietary energy in many Western diets to 8–10%.
• Polyunsaturated fatty acids. Mainly linoleic acid (18:2 ω-6): they should be about 7% of dietary energy (present British level), up to 10%. Omega-3 polyunsaturated fatty acids should be increased, both 20:5 and 22:6 from seafoods and 18:3 from canola (rapeseed) oil, etc. Monounsaturated fatty acids. Ideal intake if total fat 30%, saturates 10% and polyunsaturated 8% would be 12% of total dietary energy.

• Trans fatty acids. With the help of margarine manufacturers these are being reduced. The UK Department of Health recommends no more than 2% of dietary energy. Avoid older hard margarines.

• Dietary cholesterol. This boils down to the question of egg yolks. Eggs are a nutritious, inexpensive and convenient food. The UK Department of Health recommends for the general population no rise in cholesterol intake.

• Salt (NaCl). Restriction to under 6.0 g/day is advised for the general popula- tion (100 mmol Na). It is more important for coronary patients.

• Fish. The UK Department of Health recommends at least twice a week, preferably fatty fish. It should not be fried in saturated fat.
• Fibre. Oatmeal is recommended.
• Vegetables and fruit. These are low in fat, and contain pectin and other fibres, flavonoids and other antioxidants, and they contain folate. Expert Committees in Britain and the USA recommend five servings of different vegetables and fruit per day (400 g/day average weight).
• Soy products (not salty soy sauce) recommended.
• Alcohol in moderation, two to three drinks per day is beneficial for middle- aged people at risk of coronary heart disease but cannot be recommended for the general population because of the greater danger of accidents in younger people and of all the complications of excessive intake.
• Coffee should be instant not filtered.

Even the very controversial researcher Ancel Keys had to reach this conclusion:

So Keys reached the counter-intuitive conclusion “there can be little doubt that, other things being equal, the serum cholesterol level is markedly influenced by the proportion of calories supplied by fats in the diet, that vegetable as well as animal fats have this effect, and that the dietary cholesterol itself is unimportant at all levels of intake practicable with natural foods.” [p. 14; original at Keys A (1952): "The cholesterol problem." Voeding, 13: 539–558.] _{(Notice the date of this statement and that these conclusions about fat he drew were not unbiased but designed to promote carbohydrates.)}

Further references:

David Evans: "Cholesterol and Saturated Fat Prevent Heart Disease. Evidence from 101 Scientific Papers", Grosvenor House Publishing, Guildford, 2012. (Popular translation of and comments on selected papers, obviously biased but entertaining and not entirely incorrect.)

Frank P. Meyer: "Das Aus für die Cholesterol-Legende", BDI aktuell 11-2002, 14–19.

The International Network of Cholesterol Skeptics

Fabien De Meester, Sherma Zibadi and Ronald Ross Watson: "Modern Dietary Fat Intakes in Disease Promotion", Springer: New York, Dordrecht, 2010.

Answer 2

Eating cholesterol is bad for the body, and this why people are saying otherwise . Eating any kind of saturated fat is bad even unsaturated fats should only be used in small amounts. The only fats the body needs are the Omega-3 and Omega-6 essential fatty acids, but we only need a few grams per day of these.

To understand the problems with eating cholesterol and (saturated) fats in general, it's helpful to get back to the basics. Our bodies have evolved for a very long time (tens of millions of years) as monkeys living in trees who got the vast majority of its energy in the form of sugars and starches from foods packed with useful nutrients. This has led to our bodies becoming dependent on a very high nutrient to calorie ratio.

While our more recent ancestors did eat meat, indigenous populations who still live like our recent ancestors will typically get a far smaller fraction of their proteins from meat compared to us. They get the bulk of their essential amino acids from vegetables, but that requires eating vast amounts of vegetables and then you not only get the required amino acids but also vast amounts of other compounds. We may not require the amino acids from vegetables anymore because we eat more meat and dairy products, but if our bodies have evolved under the conditions where our bodies were flooded with all the compounds from the vast amounts of vegetables, then it's foregone conclusion that we're going to harm our bodies (perhaps in subtle ways) by eating less vegetables.

Evidence that this picture is largely correct comes from studies done on indigenous populations, like this recent study on the Tsimane people. And here you can read about the results of an older study:

Maybe the Africans were just dying early of other diseases and so never lived long enough to get heart disease? No. In the video One in a Thousand: Ending the Heart Disease Epidemic, you can see the age-matched heart attack rates in Uganda versus St. Louis. Out of 632 autopsies in Uganda, only one myocardial infarction. Out of 632 Missourians—with the same age and gender distribution—there were 136 myocardial infarctions. More than 100 times the rate of our number one killer. In fact, researchers were so blown away that they decided to do another 800 autopsies in Uganda. Still, just that one small healed infarct (meaning it wasn’t even the cause of death) out of 1,427 patients. Less than one in a thousand, whereas in the U.S., it’s an epidemic.

The problem with cholesterol in the diet is then not just the cholesterol itself, but also with this indicating that you probably eat less vegetables and fruits than that cholesterol being all that harmful by itself (but note that even a little cholesterol in the diet does do some harm). People who eat more eggs and meat and use more cooking oils, will typically not eat large amounts of vegetables. There are compounds in vegetables like broccoli (e.g. lutein and zeaxanthin) that will prevent cholesterol from oxidizing, and it's the oxidized cholesterol that causes damage. If the cholesterol doesn't do the job it's supposed to do because it's getting oxidized, your body will produce more of it, leading to even more oxidized cholesterol and more damage to your arteries.