Nutrition-wise, I have been working on a resource on zinc for the Vegetarian Nutrition Dietetic Practice Group.
The only new info from that research that I had not been considering before is that people who eat a lot of soy and who take calcium supplements might have higher zinc needs. Since I fall into both those categories, I’m wondering if that’s why I seem to benefit so much from zinc. I’m happy to report that I still have not gotten more than the mildest and shortest of colds since starting zinc supplements a number of years ago.
Many links I’ve wanted to share with readers have been building up and so I’m going to knock them all out in one post right here.
Examine.com is a website with a panel of health writers who research a wide array of nutrition supplements and other topics. They appear to do an excellent job of assessing the research. Along with the Linus Pauling Institute at Oregon State University and the Office of Dietary Supplements, I can see Examine.com as being one of my go-to sites for seeing what research is out there.
On March 10, the Washington Post ran an article (originally appearing in NewScientist) suggesting that many species of invertebrates feel pain: Do lobsters and other invertebrates feel pain? To summarize the article: octopi, squid, lobsters, crabs, and shrimp: yes. Insects: no.
Speaking of invertebrates and pain, there is a movement among some animal protectionists to promote bivalveganism. See The Ethical Case for Eating Oysters and Mussels – Part 2 at Sentientist. The author, Diana Fleischman, argues that bivalveganism can solve many of the nutrition dilemmas posed by vegan diets such as B12, iron, omega-3s, and zinc. It does seem like a decent solution for people who find it hard to thrive on vegan diets.
I have updated the blood lipids section of the VeganHealth.org article, Disease Markers of Vegetarians, with a new report from EPIC-Oxford measuring the cholesterol levels of 422 vegans living in the UK (1).
Vegan men had an average total cholesterol level of 170 mg/dl compared to 204 mg/dl for non-vegetarians. Vegan women had an average cholesterol level of 172 mg/dl compared to 195 mg/dl for non-vegetarians. More results, including those for lacto-ovo and pesco-vegetarians, can be seen in Table 1 (link).
Vegans also had a significantly lower amount of apolipoprotein B which is thought to promote fat deposits in the arteries.
The authors of the study suggest that vegans have lower cholesterol levels due to a lower body mass index, replacement of saturated fats with polyunsaturated fats, and higher fiber intakes.
References
1. Bradbury KE, Crowe FL, Appleby PN, Schmidt JA, Travis RC, Key TJ. Serum concentrations of cholesterol, apolipoprotein A-I and apolipoprotein B in a total of 1694 meat-eaters, fish-eaters, vegetarians and vegans. Eur J Clin Nutr. 2013 Dec 18. [Epub ahead of print] | link
There are a number of different types of people with genetically low LDL cholesterol levels, which normally results in somewhat lower total cholesterol (much lower in some individuals) and much less heart disease. Whether these people suffer from depression, stroke, failure to thrive, or low steroid hormones cannot necessarily be extrapolated to people who have very low cholesterol due only to diet. I also don’t know that rates of these conditions have been measured in such people (none were in the studies below), though there apparently hasn’t been an alarming amount.
It is my understanding that the people with familial hypolipoproteinemia have an inability to produce the protein fraction of the LDL, not the cholesterol portion. They definitely have less cholesterol in their blood, but this doesn’t mean they have less cholesterol in their tissues. Whereas someone with very low cholesterol in their blood due to diet might have lower cholesterol levels in their tissues.
Some readers sent me links to show that people with genetically low LDL levels have longer life spans. I checked out all the links, and followed some of them even further. Unfortunately, none answered the questions I have, but I found the information interesting enough to pass on.
PCSK9 Genetic Variant
People with a mutation in the PCSK9 gene were followed for 15 years in the Atherosclerosis Risk in Communities study from the USA (1). There are at least two variants of this mutation and in the study, 2.6% of black people had one variant that lowered their LDL cholesterol levels by 26% and their risk of heart disease by 88%. This roughly lowered their risk of having a coronary event from 1 in 10 to 1 in 100 during the 15-year time interval. Another variant was found in 3.2% of white people and lowered LDL levels 15% and their risk of heart disease by about 50%.
One would think that this reduction in heart disease would lead to a reduction in mortality, but the authors state, “[I]t is not known whether the beneficial effect of decreased LDL cholesterol levels on cardiovascular disease results in an overall reduction in mortality rates.” Interestingly, the average total cholesterol of the white people with the genetic variant was a whopping 194 mg/dl. For the black people it was 172 mg/dl.
Familial Hypolipoproteinemia
One reader sent me some links to articles on people with familial hypolipoproteinemia which results in very low LDL levels. Here is a run down of the papers:
Steinberg D, Glass CK, Witztum JL. Evidence mandating earlier and more aggressive treatment of hypercholesterolemia. Circulation. 2008 Aug 5;118(6):672-7 (link)
This is a review article that says, “Third, in some kindreds with hypobetalipoproteinemia, LDL cholesterol levels can be < 15 mg/dL throughout life, yet the affected members show perfectly normal growth and development and actually have increased longevity. (40, 41)”
Citation 40, from that quotation directly above, is this paper:
Steinberg D, Grundy SM, Mok HY, Turner JD, Weinstein DB, Brown WV, Albers JJ. Metabolic studies in an unusual case of asymptomatic familial hypobetalipoproteinemia with hypolphalipoproteinemia and fasting chylomicronemia. J Clin Invest. 1979 Jul;64(1):292-301 (link)
It is an article describing one man, age 67, known as “HJB” with an unusual variant of hypobetalipoproteinemia and a total cholesterol level of 47 mg/dl. It doesn’t discuss longevity of such people in general.
Citation 41 is:
Young SG, Bertics SJ, Curtiss LK, Dubois BW, Witztum JL. Genetic analysis of a kindred with familial hypobetalipoproteinemia. Evidence for two separate gene defects: one associated with an abnormal apolipoprotein B species, apolipoprotein B-37; and a second associated with low plasma concentrations of apolipoprotein B-100. J Clin Invest. 1987 Jun;79(6):1842-51 (link)
This paper describes 19 members of HJB’s family (including HJB), whose total cholesterol levels ranged from 31 mg/dl (HJB himself, by this time) to 130 mg/dl, with an average of 84 mg/dl. The only mention of longevity was that HJB was in excellent health at age 75, one of his family members had lived to 95, and one was said to have lived to 105.
Another study passed on by this reader:
Glueck CJ, Kelley W, Gupta A, Fontaine RN, Wang P, Gartside PS. Prospective 10-year evaluation of hypobetalipoproteinemia in a cohort of 772 firefighters and cross-sectional evaluation of hypocholesterolemia in 1,479 men in the National Health and Nutrition Examination Survey I. Metabolism. 1997 Jun;46(6):625-33. (link)
It doesn’t appear to be available in electronic form; so going by the abstract, this study measured the rates of genetically low LDL and total cholesterol levels among male firefighters in Cincinnati. It didn’t measure heart disease or mortality risk.
Finally, in the order they were presented to me, there is a study which actually does appear to suggest that people with familial hypolipoproteinemia live longer:
It was a study of 26 different families with familial hypolipoproteinemia. The abstract says, “Expectation of life for males and females from kindreds with hypobeta lipoproteinemia was 9 and 12 years longer (p less than or equal to 0.002) than that indicated by population statistics for U.S. white populations, whereas expectation of life for males and females from kindreds with hyperalpha lipoproteinemia was 5 and 7 years longer (p less than 0.02).”
This paper was not available online or at my local university library (UC Davis), but I’m hoping to get a copy at some point. And there should be some caution here in suggesting this is proof that genetically low LDL increases life expectancy by 5 to 12 years. Comparing disease rates to the average population does not allow for much adjustment for confounding variables of which there could be many in these 26 families compared to the population at large. But even if such people do have longer life spans, it doesn’t shed much light on the questions I have. As I mentioned in Low Cholesterol: Part 1, I’m not debating whether low LDL prevents heart disease, there is good evidence that it does.
Hunter-Gatherer Populations
The above studies were done on people with genetic mutations, not your average people. The commenter who sent me those studies also said that “Optimal low density lipoprotein is 50 to 70 mg/dl; lower is better and physiologically normal” [my emphasis]. What does “physiologically normal” mean? Read on…it might mean the average cholesterol of people who are very active, eating a diet of about 20% fat.
As evidence, the commenter linked to:
O’Keefe J, Jr, Cordain L, Harris W, Moe R, Vogel R. Optimal low-density lipoprotein is 50 to 70 mg/dl: Lower is better and physiologically normal. J Am Coll Cardiol. 2004;43(11):2142-2146 (link)
This is merely a review article that says, “Evidence from hunter-gatherer populations while they were still following their indigenous lifestyles showed no evidence for atherosclerosis, even in individuals living into the seventh and eighth decades of life (15,16). These populations had total cholesterol levels of 100 to 150 mg/dl…”
Citation 15 from the quotation above is a citation for yet another review:
Cordain L, Eaton SB, Miller JB, Mann N, Hill K. The paradoxical nature of hunter-gatherer diets: meat-based, yet non-atherogenic. Eur J Clin Nutr. 2002 Mar;56 Suppl 1:S42-52 (link)
It says:
“Over the past 64y, anthropological research has consistently demonstrated relatively low serum cholesterol and triacylglycerol levels among indigenous populations that derive the majority of their diet from animal products (Bang & Dyerberg, 1980; Biss et al, 1971; Corcoran & Rabinowitch, 1937; Day et al, 1976; Eaton et al, 1988a; Leonard et al, 1994; Scott et al, 1958; Shaper et al, 1961; Wilber & Levine, 1950).”
I obtained two papers from this list (and could find no abstract for a third, Bang & Dyerberg):
Biss K, Ho KJ, Mikkelson B, Lewis L, Taylor CB. Some unique biologic characteristics of the Masai of East Africa. N Engl J Med. 1971 Apr 1;284(13):694-9 (link)
The Masai, an East African Tribe that had intermingled very little with other African tribes, had a very interesting diet (when this paper was published). They ate mostly milk, 3 – 5 liters per day. They also ate cow’s blood, and the meat of cattle, goats, and sheep. Yet their cholesterol levels were very low, an average of 135 mg/dl. How did they do it?
The authors of the study did an experiment in which they challenged some of the Masai with 2,000 mg of cholesterol per day for 8 weeks! They did not have higher levels of cholesterol excretion (or lower absorption) but rather showed an impressive ability to decrease their internal cholesterol production in the face of eating such high amounts. Autopsies of some of the Masai showed them to have a “paucity of atherosclerosis.”
In other ways, the Masai are (or were) not doing so well with high rates of malaria and tuberculosis.
I don’t think the Masai’s situation can shed much light on what normal physiological cholesterol levels would be for people not in their genetic situation. I didn’t bother looking up the older citations from Cordain et al, but did check out the one from 1994:
Leonard WR, Crawford MH, Comuzzie AG & Sukernik RI (1994): Correlates of low serum lipid levels among the Evenki herders of Siberia. Am. J. Hum. Biol. 6, 329 – 338 (link
The Evenki had an average total cholesterol level of 139 mg/dl for men and 148 mg/dl for women. Despite eating large amounts of animal products, their diets were only 18-19% fat.
The researchers thought that the Evenki’s low cholesterol levels were primarily due to their high activity; the men were more active in herding than the women, cholesterol increased with age in the men only, and the men who lived in the village rather than the herding areas had higher levels. The differences in cholesterol levels could not be explained only by differences in body weight.
The authors said, “Among the African pastoral groups, only the Masai have lower total cholesterol levels than the Evenki.” Longevity and heart disease were not mentioned. Unlike the Masai, the Evenki do not appear to have a genetic propensity for keeping cholesterol low (though this cannot be ruled out).
Interestingly, Cordain also says:
“For the majority (53% n=122) of the world’s foraging cultures the dietary fat intake would lie between 36 and 43% of total energy (Cordain et al, 2000a), values not dissimilar from current Western intakes (McDowell et al, 1994). Despite this dietary characteristic, the available evidence suggests that hunter-gatherers were generally free of the signs and symptoms of [cardiovascular disease].”
I didn’t track down the citations for that statement.
Citation 16 from O’Keefe (above) is to another paper by Cordain and I decided not to track down any more of Cordain’s references as this was taking too much time and shedding very little light on my question of whether a cholesterol of ≤100 mg/dl, caused by diet and not genetic variants, could result in some vegans not thriving.
I have not answered the question about low cholesterol levels (from diet) and steroid hormone production. None of the studies I reviewed in these posts addressed those questions and I hope to look into it more after going through the backlog of other studies I intend to post about.
I don’t mean to dig my heels in and be hyper-skeptical, but I just don’t think these populations exclude the possibilities of very low cholesterol being a problem in failure to thrive for some people.
References
1. Cohen JC, Boerwinkle E, Mosley TH Jr, Hobbs HH. Sequence variations in PCSK9, low LDL, and protection against coronary heart disease. N Engl J Med. 2006 Mar 23;354(12):1264-72. | link
It’s been so long since I wrote anything, some of you might have been wondering if I had died from low cholesterol. No, I am still here plugging away. But unlike Dr. Michael Greger, whose Latest in Clinical Nutrition: Volume 15 is now out on DVD, I have not been working at a speed that violates Einstein’s theory of relativity.
My post of August 28th, The Winter of Their Discontent, caused quite a firestorm of comments. (Whoops! – I mean it was correlated with a firestorm of comments.) Let’s just say that some people do not care for the suggestion that cholesterol levels could get too low.
I’ve spent much of my nutrition time over the last few weeks checking out links to studies that people posted in their comments, along with many others that I found along the way, and want to share what I have found. But first, I want to clarify a few things.
The question I am trying to answer is: at what point, if any, does total cholesterol become so low that it could impact things such as steroid hormone production or mood in some people? And as a corollary: Is low cholesterol possibly a culprit when it comes to the egg cravings some vegans get?
One thing I have never said, and am not suggesting, is that low LDL cholesterol levels don’t protect against atherosclerosis (or even mortality) and I’m not sure why people have jumped to the conclusion that I am implying this.
Unfortunately, I have not done a good job of documenting the anecdotal reports of vegans who have come to me with problems who also have very low cholesterol. One guy was passing out unless he ate cheese, and his cholesterol levels were about 100 mg/dl. My recollection is that adding plant saturated fat didn’t help him. A few other people have had loss of libido which improved upon adding coconut oil (I don’t know what their cholesterol levels were). Another person with cholesterol of 94 mg/dl was suffering from mild fatigue, headaches, and anxiety. Kristen, the ex-vegan featured in The Winter of Their Discontent, had an irregular menstrual cycle (among other things) and a cholesterol of 95 mg/dl. However, I also know vegans with cholesterol levels below 100 mg/dl who appear to be thriving.
So what do we know about low cholesterol?
Low Cholesterol and Hemorrhagic Stroke
During the 1990s, it became known that cholesterol was associated with mortality in a U-shaped curve. In other words, both high and low cholesterol levels were associated with higher mortality – though much more on the high cholesterol end. At the time, the thinking was that most of the association of higher mortality with low cholesterol was a merely a manifestation of early cancer, poor nutrition from depression, or liver disease and poor nutrition from alcoholism. The remaining cause of increased mortality was thought to be due to an increase in risk for hemorrhagic stroke (which is a much less prevalent form of stroke than the more typical ischemic stroke where a blood vessel to the brain is blocked).
The most recent, comprehensive review I found on low cholesterol and hemorrhagic stroke was a 2013 meta-analysis of prospective studies (1). Among 17 studies, they found that high total cholesterol was associated with a 31% decreased risk of hemorrhagic stroke (.69, 0.59–0.81), although publication bias was detected. The vast majority of these studies adjusted their results for blood pressure and alcohol intake, among other variables. Lower LDL, but not lower HDL, was also associated with an increased risk of stroke.
It should be noted that lowering one’s LDL decreases heart disease risk by so much that you are better off with a low LDL even if it does increase the risk for hemorrhagic stroke. It is also still possible that these studies had confounding variables that could not be fully adjusted.
The authors finish their paper by saying, “Our results remind clinicians to take this caution during intensive lipid-lowering therapy. Further studies are needed to investigate the underlying pathogenesis better, and identify subjects who would benefit most from lowering cholesterol without risk of hemorrhagic stroke.”
With few exceptions, the low cholesterol category was less than about 150 mg/dl; the average cholesterol in the lowest categories was rarely given. I have not taken the time to read each study and see if there is any way to detect trends as to whether the findings were different based on the different cholesterol levels being compared or the level or types of adjustments.
A reader pointed out a study from Korea (2), which was included in the 2013 meta-analysis (1), in which the risk of hemorrhagic stroke disappeared after adjusting for blood pressure.
There were 8,319 people in the lowest cholesterol category of 130 mg/dl or less (average cholesterol not given). The decreased risk of having a hemorrhagic stroke in the fully adjusted model (including blood pressure and alcohol consumption) for every 38.6 mg/dl (1 mmol/l) increase in total cholesterol was 9% (.91, .87-.95).
However, when they broke the cohort into two groups, those with high blood pressure and those with normal blood pressure, the effect did not hold for those with normal blood pressure. There was still a non-significant trend towards lower stroke in those with “medium” cholesterol levels as compared to the lowest category.
They broke the group up even further. Among those with high blood pressure, they stratified the results for gamma glutamyl transferase (GGT) which reflects alcohol consumption. At low concentrations of GGT, low cholesterol was not associated with a higher risk of hemorrhagic stroke among those with high blood pressure.
The researchers conclude, “In effect, low blood cholesterol may act as a marker of the health damaging effects of alcohol, rather than be a cause of hemorrhagic stroke.”
Based on the results from the 2013 meta-analysis, I’m not sure that this one study from Korea can be considered to put to rest the entire question of whether low cholesterol, in itself, can contribute to hemorrhagic stroke. Apparently the authors of the meta-analysis didn’t think so, but I’m actually inclined to think perhaps it does.
In any case, if you have low cholesterol (below 150 mg/dl) and have either high blood pressure or drink alcohol heavily, you should talk to a doctor about your risk for hemorrhagic stroke.
Low Cholesterol and Depression
The most recent, comprehensive report I found was a 2008 review from the journal, Psychiatry (3). They sum up their findings nicely in the introduction:
“A number of investigators have found a possible relationship between low serum cholesterol levels and mood disorders. In addition, low serum cholesterol levels have been associated with suicidal ideation [suicidal thoughts] and suicide attempts. While the pathophysiology of this association remains unknown, some researchers have postulated that there may be a relationship between altered lipid metabolism and changes in serotonin functioning. In addition, some researchers have found that the pharmacological treatment of depression results in increased serum cholesterol levels. While controversies and inconsistencies characterize this area of study, it appears reasonable to conclude the following: (a) alterations in lipid metabolism may be one of several risk factors for the subsequent development of depression and/or suicidal ideation/suicide attempts (i.e., a non-specific contributory variable) and/or (b) low serum cholesterol levels are an inconsistent but possible biological marker for the manifestation of these phenomena in some individuals.”
In other words, low cholesterol might cause depression and suicidal thoughts/attempts in some individuals. Could this be related to why some ex-vegans claim their mood became much improved upon going back to eating animal products?
More research is needed. Stay tuned for Part II (now available).
References
1. Wang X, Dong Y, Qi X, Huang C, Hou L. Cholesterol levels and risk of hemorrhagic stroke: a systematic review and meta-analysis. Stroke. 2013 Jul;44(7):1833-9. doi: 10.1161/STROKEAHA.113.001326. Epub 2013 May 23. | link
2. Ebrahim S, Sung J, Song YM, Ferrer RL, Lawlor DA, Davey Smith G. Serum cholesterol, haemorrhagic stroke, ischaemic stroke, and myocardial infarction: Korean national health system prospective cohort study. BMJ. 2006 Jul 1;333(7557):22. Epub 2006 Jun 6. Erratum in: BMJ. 2006 Sep 2;333(7566):468. | link
3. Sansone RA. Cholesterol quandaries: relationship to depression and the suicidal experience. Psychiatry (Edgmont). 2008 Mar;5(3):22-34. | link
The Linus Pauling Institute says, “Vitamin A and retinoic acid play a central role in the development and differentiation of white blood cells, such as lymphocytes, which play critical roles in the immune response (1).”
Unlike omnivores, vegans do not have a direct, dietary source of vitamin A, but rather get it indirectly via carotenoids (mainly beta-carotene). Beta-carotene is fat-soluble. It seems theoretically, possible then, that a low intake of carotenoids or fat could contribute to lower vitamin A status and white blood cell count (WBC).
This is purely hypothetical; to my knowledge vitamin A levels have not been measured in vegans and other signs of low vitamin A status have not been a noted problem. Anecdotally, I had been eating plenty of beta-carotene and fat at the last measurement of my WBC which showed them to be below normal.
Paul Appleby, of EPIC, passed on a study to me of a clinical trial using a “Daniel Fast” from the University of Memphis (2). In this trial, mostly healthy and some vegetarian subjects (13 men, 30 women; 20-62 years old) went on a Daniel Fast for 21 days, eating no processed or packaged food and only plant foods (as much as they wanted). Their WBC went from an average of 5.7 to 5.0 (2). 5.0 is within the normal range, but on the lower end (normal being about 3.5 to 12.5 billion per liter).
The authors of the Daniel Fast study say, “It has been suggested that ingestion of food additives and preservatives can increase white blood cell count by triggering an immune response due to a sensing of invading pathogens from the food stuff; however, we are unaware of any scientific reports that confirm this hypothesis.” I should point out that lots of things have been suggested, but it doesn’t seem impossible that vegans generally eat less food additives and preservatives and this could be contributing to low WBC.
I have added this information to VeganHealth’s article on White Blood Cells.
There were some other interesting things about this study. Here are the before and after (or during in the case of the nutrient intakes):
The authors did an analysis which showed that the improvements in these parameters did not occur in only the unhealthier subjects, but rather across the board. They say, “It is interesting to note that even those subjects who were vegetarian prior to starting the fast experienced dramatic reductions in total and LDL-[cholesterol], in addition to improvements in other markers. Clearly, the exclusion of meat from the diet (as is the case for vegetarians) is not the only dietary factor involved in raising circulating cholesterol and other risk factors for cardiovascular and metabolic disease.”
It should be noted that this trial had no control group and was not randomized in any way.
I found this interesting because even though the subjects didn’t lose much weight (the weight change wasn’t even statistically significant), their blood pressure and cholesterol levels went down substantially in only 3 weeks. That’s impressive. But does it mean that it is the diet that everyone should be on all the time, indefinitely?
Stay tuned.
Reference
1. Linus Pauling Institute. Micronutrient Information Center. Vitamin A. Accessed 5/20/13 | link
2. Bloomer RJ, Kabir MM, Canale RE, Trepanowski JF, Marshall KE, Farney TM, Hammond KG. Effect of a 21 day Daniel Fast on metabolic and cardiovascular disease risk factors in men and women. Lipids Health Dis. 2010 Sep 3;9:94. | link
Heart disease rates of all vegetarians compared to all non-vegetarians were calculated for EPIC-Oxford from 1993 until 2009 (1). These participants were all thought to be free of heart disease at the beginning of the study. The results showed that vegetarians had a statistically significant, ~30% reduced risk of heart disease (.68, .58-.81). That is a fairly impressive finding for a nutrition study.
All results were adjusted for age, smoking, alcohol, physical activity, education, socioeconomic status, oral contraceptives, and hormone replacement therapy. The findings held after adjusting for body mass index (BMI) and removing the first two years of follow-up. (See the table in EPIC-Oxford: Heart Disease (2013) of VeganHealth.org for the relative risks.)
The researchers believed the difference in heart disease rates to be due mainly to the lower non-HDL cholesterol and systolic blood pressure of the vegetarians. The non-vegetarians had an average total cholesterol level of 222 mg/dl vs. 203 mg/dl for the vegetarians, while HDL was 52 vs. 50 mg/dl respectively. Systolic blood pressure was 134 for non-vegetarians and 131 mm Hg for vegetarians.
Given that vegetarians had cholesterol levels an average of 203 mg/dl – a full 33% higher than the 150 mg/dl, upper-end-of-healthy that many of the very low-fat doctors recommend – it might come as a surprise to learn that, in the authors’ words, “On the basis of the absolute rates of hospitalization or death from IHD [ischemic heart disease], the cumulative probability of IHD between ages 50 and 70 y was 6.8% for nonvegetarians compared with 4.6% for vegetarians.”
In other words, with cholesterol levels that high in both groups, you might think they would have a very high rate of heart disease, but, from what I can tell (see reference #2), their rates are relatively comparable to the general population of the United States (2).
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Reference
1. Crowe FL, Appleby PN, Travis RC, Key TJ. Risk of hospitalization or death from ischemic heart disease among British vegetarians and nonvegetarians: results from the EPIC-Oxford cohort study. Am J Clin Nutr. 2013 Jan 30. [Epub ahead of print] | link
2. Prevalence of Coronary Heart Disease — United States, 2006–2010
Morbidity and Mortality Weekly Report (MMWR) for October 14, 2011. Accessed February 3, 2013. | link (PDF)
Regarding your cholesterol article, I was wondering which plants contain cholesterol and how much. I saw some biscuits that contained .4 mg of cholesterol per 100 g of the product. The company claimed all ingredients were plant based, but there was quite a stir in a vegan forum regarding that cholesterol amount. Is there an article you can refer me to.
Answer:
Unbeknownst to most people, the labels on packaged food normally do not represent a laboratory analysis where the various nutrients have been directly measured. Rather, the company takes a list of ingredients and plugs them into a software package which then produces the label based on a combination of all the ingredients and serving size. If one of the ingredients they plug in typically contains cholesterol, then it will contain cholesterol in the result.
As a rule, the USDA nutrient database, which most of these nutrition label generating software applications are based on, just assumes a cholesterol amount of zero for plant foods. Take a look at raw baby carrots at PeaCounter. It lists cholesterol as zero, but it also lists the “data points” as zero. In other words, they didn’t measure it, they just assumed it to be zero.
I don’t know all the ins and outs of the process of producing labels for all foods, and it would seem to me that normally, for biscuits, the company would be plugging in basic nutrients and if they were of plant origin, they would not register any cholesterol on a nutrition label. But in this case, I would guess that the .4 mg of cholesterol shown on this supposedly vegan food was simply a result of inaccurate ingredients plugged into the software. It definitely wasn’t that they included enough plant foods with cholesterol that the cholesterol actually registered in a laboratory analysis.
Here is an article that lists the cholesterol amounts in some plant foods:
Behrman EJ, Gopalan V. Cholesterol and plants. The Journal of Chemical Education. 2005. 82(12):1791. | link to pre-publication PDF
And here are a few of the listings for comparison:
Smith-Lemli-Opitz Syndrome (SMOS) is a genetic mutation that impairs the body’s ability to produce its own cholesterol. This very small group of people (1 in 20,000) would need cholesterol in their diet. Any suggestions on how to answer this? Are there any vegan cholesterol sources?
Answer:
The listing for Smith-Lemli-Opitz Syndrome Treatment & Management at Medscape says, “Currently, no treatment has proven effective for patients with Smith-Lemli-Opitz syndrome (SLOS). Potentially, cholesterol supplementation is a logical treatment because it may be expected to raise plasma and tissue cholesterol levels…. Therapeutic trials are underway.”
Someone with SMOS should be under the care of a physician who is probably instructing them (or their parents) as to whether they need cholesterol supplementation and how much they need in their diet.
I am not aware of any vegan sources of cholesterol with which someone could supplement. My understanding is that some plants contain cholesterol, but only in miniscule amounts. For committed vegans, obtaining eggs from someone with companion chickens would be a way to get cholesterol in the diet while causing minimal or no harm to animals. Oysters, clams, or mussels might be another option.
I have a question in my inbox from someone asking if there “is anything to the ‘no oil’ diets,” such that Dr. Caldwell Esselstyn promotes. My answer is – certainly there is something to it. Dr. Esselstyn (1) and Dr. Dean Ornish (2) have used a very low-fat, plant-based diet (10% of the calories as fat) as part of a cholesterol-lowering program that has decreased the amount of plaque in patients’ arteries and led to much better outcomes than typical treatment for heart disease. Dr. Neal Barnard and the Physician’s Committee for Responsible Medicine have used a very low-fat, vegan diet to treat type-2 diabetes with impressive outcomes (link).
But is it the only healthy diet that all vegans should eat? Let’s look at some other evidence.
A 2000 cross-sectional report (3) on cholesterol levels in men from EPIC-Oxford found the following:
Meat-Eaters
Vegan
fat
34%
30%
cholesterol (mg/dl)
191
158
saturated fat
12%
5%
calories
2,461
1,931
So the vegan men were eating a diet of 30% of their calories as fat while still maintaining cholesterol levels of 158 mg/dl. Some people would consider this level of cholesterol too high, and while trials of people with heart disease who lower their cholesterol levels to below 150 mg/dl have shown a great benefit in doing so, it is not clear (to me, anyway) that people without a history of high cholesterol and heart disease need to go as low as 150 mg/dl. Low calories (or body weight) and saturated fat may be the most important aspect of lowering cholesterol levels.
A cross-sectional study on cholesterol levels is not the highest form of evidence compared to the clinical trials I mentioned earlier. What about trials of higher fat diets?
The Eco-Atkins diet, a high-protein, higher fat version of a vegan diet found better changes in blood lipids and higher levels of satiety when compared to a lower fat, near-vegan diet (4). But this trial only lasted 4 weeks, not nearly long enough to measure heart disease outcomes. Cholesterol levels of the people on Eco-Atkins went from 257 to 205 mg/dl – nowhere near as low as the very low-fat diets generally achieve, but, again, it was only four weeks long. [2014 Update on Eco-Atkins]
Most of the very low-fat diets do not allow for many nuts. While nuts have consistently been associated with positive health outcomes (lower body weight, better cholesterol levels, etc.), one vegan doctor, who uses low-fat diets to treat heart disease, told me that many of his patients binge on nuts when they are part of their diets and so he suggests they avoid them. I’ve heard from others that if they eat nuts they gain weight. It doesn’t completely surprise me that someone on a very low-fat diet might binge on nuts – they might be craving the fat or protein. But if you are someone who can eat nuts in moderation, then having some is most likely beneficial for preventing heart disease and long-term weight maintenance.
Though it may be rare, or even extremely rare, some people who follow a very low-fat diet find that they lose their libido and regain it upon eating more fat.
Earlier this month, Jeff Nelson of Vegsource.com wrote an article, How the ethical argument fails veganism. In it, he disagrees with my co-founder of Vegan Outreach, Matt Ball, and my co-author of Vegan For Life, Ginny Messina, as to whether the health argument is the way to go when spreading veganism. He also disparages “AR dietitians” in general, of which I can’t help but notice that I am one.
Aside from the fact that Matt nor I care about veganism as anything more than a tool for protecting animals and the environment, the central thesis of Nelson’s article is that people who become vegan for health reasons are more likely to stick with the diet than people who go vegan for ethical reasons. He says that people who go vegan for ethical reasons are usually not as educated about health and nutrition due to being persuaded by organizations that do not give them adequate information; so they eat processed foods and end up concluding that a vegan diet is not healthier. The people who go vegan for health reasons, on the other hand, understand the importance of avoiding processed foods and oils, and their health improves.
While many people do well on a whole-foods only, very low-fat vegan diet, my experience has been that such diets can sometimes result in failure to thrive, while many people do thrive on a vegan diet that includes more fat and processed foods.
The vegans I know are mostly animal advocates, and, therefore, are dedicated to being vegan. Very few of them had been diagnosed with heart disease or type-2 diabetes before becoming vegan, so they are not necessarily in the same boat as people who become vegan to treat their disease. The vast majority of the vegan, animal advocates I have know have stayed vegan, and most eat processed foods. From soy foods to french fries to desserts made with white flour and sugar, the vegans I know eat ’em. Of course, most of them also eat more fruit, vegetables, whole grains, legumes and nuts than the average American.
My cholesterol tends to be around 150 mg/dl. If I were eating a very low-fat diet, it might be even lower, possibly decreasing my risk for heart disease. But I crave protein and feel better when eating a good amount, possibly due to my fairly intensive weight lifting. I do much better eating soyfoods and other processed foods such as pasta, than when eating only whole plant foods.
There are health issues that might prevent people from eating only whole foods, such as digestive problems, and those have to be dealt with on a case by case basis.
I generally tell people who have metabolic syndrome that they should tend towards a whole-foods diet, greatly limiting added oils but including nuts, while those who are not as much at risk can afford to eat more processed foods, especially those high in protein and/or pastas (which generally do not raise blood sugar as high as other processed grains). Monitoring your weight, cholesterol, and blood sugar levels is a good idea to see if the diet you are eating is working for you.
At some point there might be clinical trials examining cardiac outcomes in people on vegan diets that are not so low in fat or in vegans who have not been diagnosed with heart disease. We do have some data on heart disease in vegans from the 1999 meta-analysis, but it isn’t much.
References
1. Esselstyn CB Jr. Updating a 12-year experience with arrest and reversal therapy for coronary heart disease (an overdue requiem for palliative cardiology). Am J Cardiol. 1999 Aug 1;84(3):339-41, A8. | link
2. Ornish D, Scherwitz LW, Billings JH, Brown SE, Gould KL, Merritt TA, Sparler S, Armstrong WT, Ports TA, Kirkeeide RL, Hogeboom C, Brand RJ. Intensive lifestyle changes for reversal of coronary heart disease. JAMA. 1998 Dec 16;280(23):2001-7. Erratum in: JAMA 1999 Apr 21;281(15):1380. | link
3. Allen NE, Appleby PN, Davey GK, Key TJ. Hormones and diet: low insulin-like growth factor-I but normal bioavailable androgens in vegan men. Br J Cancer. 2000 Jul;83(1):95-7. | Link
4. Jenkins DJ, Wong JM, Kendall CW, Esfahani A, Ng VW, Leong TC, Faulkner DA, Vidgen E, Greaves KA, Paul G, Singer W. The effect of a plant-based low-carbohydrate (“Eco-Atkins”) diet on body weight and blood lipid concentrations in hyperlipidemic subjects. Arch Intern Med. 2009 Jun 8;169(11):1046-54. Erratum in: Arch Intern Med. 2009 Sep 14;169(16):1490. | link
Here’s something I’ve been mentioning in my talks lately. A 2000 study measured the percentage of calories as fat in the diet as well as cholesterol levels in a subset of EPIC-Oxford vegan and non-vegan men. Here is what they found:
Meat Eaters
Vegans
% fat
34
30
blood cholesterol (mg/dl)
191
158
% saturated fat
12%
5%
calories
2,461
1,931
fiber (g)
18
28
cholesterol (mg)
327
21*
total fat (g)
93
64
*Cholesterol intake by vegans likely due to using foods that contained small amounts of animal products in calculating the nutrient composition of foods. In other words, using bread made with animal products versus vegan bread in the nutrient calculations. Also possible that some vegan participants were not 100% vegan.
Vegans ate 30% of their calories as fat compared to 34% for meat-eaters. Not a huge difference and many people would be horrified at such a high fat intake on behalf of the vegans. Yet, their cholesterol levels were well below what is commonly considered the danger zone.
What accounts for this? The vegans’ much lower intake of saturated fat probably explains a lot. But the vegans’ 20% fewer calories also probably accounts for much of their lower cholesterol levels. Addendum 1/27/12: Additionally, higher fiber intake and zero or near-zero cholesterol intake all likely contribute to the vegans’ lower cholesterol levels. Clarification 1/30/12: People who exercise a lot can eat more calories without cholesterol levels increasing as long as they are not eating so much that they gain body fat (thanks, Ginny).
Some people might point out that ideal cholesterol levels are actually less than 150 mg/dl, so 158 mg/dl is too high. While many clinical trials in people with heart disease (and normally on cholesterol-lowering medication) show a benefit to getting levels below 150 mg/dl, I have not seen evidence that this is ideal, or even desirable in people without diagnosed heart disease or normally high cholesterol. Instead, the observational studies I’ve seen measuring cholesterol levels and mortality have not shown a benefit from cholesterol levels less than 160 mg/dl.
I would not completely rule out the idea that studies have not shown reduced mortality in people with cholesterol levels less than 160 mg/dl because they have not included enough people with cholesterol levels that low and who do not have such low levels due to undiagnosed disease. But “not completely ruling out something” is a far cry from saying there is good evidence that it is true.
The reason I think this is particularly important is anecdotal evidence that people on long-term, low-fat diets can find them hard to stick with. I know there are some exceptions – people who find them easy to stick with, but I sense that there are more who find it difficult. When people crave meat, they tend to think they are craving the protein. But meat is also about 50% fat on average and it would not surprise me if such people are often craving fat as much or more than protein. Eating a diet closer to 30% fat might prevent such cravings.
Yes, lots of qualifiers above that I’m not 100% certain of everything I’m saying. But I think there is enough evidence that I should share it with readers rather than just keeping it to myself until “further studies” are done.
Reference
Allen NE, Appleby PN, Davey GK, Key TJ. Hormones and diet: low insulin-like growth factor-I but normal bioavailable androgens in vegan men. Br J Cancer. 2000 Jul;83(1):95-7. Link
