At first glance, the Paleo refutation of the mainstream wisdom that eating cholesterol will give you heart disease is very reassuring. The studies backing up conventional wisdom are cherry-picked and weak, there’s no need to run screaming from every egg yolk you see, and even butter is cleared of all guilt and encouraged as a rich source of healthy fat and vitamins! But there’s a difference between dietary cholesterol and blood cholesterol, and while dietary cholesterol is far from the villain it’s made out to be, it’s not completely clear that blood cholesterol doesn’t matter.
Precisely how it matters is hotly debated. Some people argue that it isn’t the cause of plaque in the arteries, but rather another symptom of whatever problem is also causing the plaque, and a useful indication that something is wrong. Others claim that “cholesterol” itself is too broad a term and the real problem is only with oxidized LDL cholesterol. From this point of view, some other problem causes inflammation and oxidized stress in the body, which turns innocent LDL cholesterol into plaque-forming oxidized LDL, but that’s not the fault of the cholesterol. Others disagree completely, claiming that blood cholesterol is just a red herring and the causes of heart disease are unrelated.
The one clear message of the entire debate is that even Paleo-friendly scientists don’t completely understand the role of cholesterol in the body, and it’s possible that high blood cholesterol (especially LDL cholesterol) can be a bad sign. It can be a nasty shock to follow a Paleo diet faithfully, secure in the knowledge that dietary cholesterol and blood cholesterol are unrelated, and then get a blood test that says otherwise. It’s a betrayal: what happened? Was conventional wisdom right all along? Should you immediately start popping statins and piling on the whole grains? Whatever relationship was or wasn’t correlated in a study loses a lot of significance when the numbers get personal.
But even high cholesterol numbers after adopting a Paleo diet don’t mean that the dietary cholesterol is to blame. Cholesterol levels can fluctuate with a number of physical changes ranging from hypothyroid syndrome to menopause to weight loss. Instead of focusing on the cholesterol itself, try to understand why your numbers might have gone up, and then making a plan accordingly.
A dysfunctional thyroid gland is one of the most common causes of high cholesterol that has nothing to do with how much cholesterol you eat. The thyroid is the air traffic control tower for your hormonal system. It regulates everything from metabolism to sex hormones. Thyroid function also affects the levels of cholesterol in the blood, especially LDL cholesterol, and when the thyroid isn’t producing enough hormones (hypothyroidism), levels of cholesterol can rise.
Hypothyroidism contributes to higher cholesterol in the blood, because the thyroid hormone T3 stimulates production of LDL receptors, which ferry the LDL cholesterol out of the bloodstream and into cells (where it can be used for all kinds of things, including the production of other hormones). Low levels of T3, and fewer LDL receptors, will cause more LDL cholesterol to stay in the bloodstream.
Even if you’ve never been diagnosed with hypothyroid, this might still be applicable. Many people have subclinical hypothyroidism: they aren’t aware that they have hypothyroid problems until the Paleo transition period brings out the symptoms. The thyroid needs some carbohydrates, so suddenly switching from the carb-based modern diet to Paleo (especially to a ketogenic version of Paleo) can trigger thyroid symptoms. Iodine is also important, but when many people switch to Paleo they dramatically cut their iodine consumption because they’re no longer eating processed foods loaded with iodized salt.
This doesn’t mean that Paleo isn’t helpful for hypothyroidism. Since gluten, inflammation, and metabolic dysfunction are major triggers of thyroid problems, a Paleo diet is one of the best long-term treatments. But since carbs and iodine are so central to thyroid health, it’s important to optimize the diet accordingly.
Because they jump right in to very low carb Paleo without being aware that they have hypothyroid issues, many people see a spike in hypothyroid symptoms (including higher cholesterol) when they switch to Paleo. This can actually be helpful, though, because it points out a problem that had been flying under the radar – a problem that has nothing to do with cholesterol itself. If your cholesterol took a drastic jump on Paleo, it’s worth getting your thyroid checked.
Hormonal dysfunction brought on by an underactive thyroid is one problem, but in women, several natural hormonal changes can cause cholesterol levels to rise and fall. During a healthy menstrual cycle, it’s perfectly normal for levels of cholesterol to fluctuate. For women taking oral contraceptives, this variation is even more pronounced. If a woman’s pre-Paleo and post-Paleo cholesterol levels only show a slight change, it might just be that she took the two tests at different points in her menstrual cycle.
More drastic hormonal changes also typically involve higher cholesterol levels. Women with PCOS, a hormonal disease characterized by extreme hormone dysfunction, have altered cholesterol levels (higher LDL and lower HDL). Pregnancy is another condition often accompanied by elevated levels of cholesterol. Typically, the level of cholesterol rises during the second trimester and peaks in the third. This shouldn’t be concerning to Paleo moms, because it makes perfect biological sense: cholesterol is a vital substance for brain development and the healthy growth of the baby. This increase in cholesterol is not associated with an increased risk of heart problems, and it naturally decreases during breastfeeding.
Menopause marks another major hormonal shift, and, like pregnancy, it’s associated with an elevated level of cholesterol. The link between menopause and cholesterol is particularly interesting from a Paleo standpoint, because menopause is when women’s risk of heart disease starts to more closely approximate men’s. Premenopausal women have a much lower rate of cardiac problems, but by age 80, the risk of CHD (Coronary Heart Disease) is gender-neutral. Understanding this transition could give us valuable information about cholesterol and how it relates to overall health.
Unfortunately the research in this area is conflicting and constantly changing. One theory is that these hormonal changes in cholesterol have something to do with estrogen levels in the body, but the specific relationship between estrogen and cholesterol is very unclear. It may be that estrogen directly affects serum cholesterol levels (possibly through the protein CETP, part of the cholesterol reuptake pathway that removes cholesterol from the rest of the body and returns it to the liver).
Research into hormone replacement therapy for menopausal women, however, has seriously complicated the proposed relationships among estrogen, cholesterol, and CHD. Since the increase in menopausal cholesterol seems to be associated with lower estrogen levels, hormone replacement therapy (artificial supplementation with estrogen to reduce symptoms of menopause) was formerly thought to lower the risk of CHD by lowering cholesterol. It does seem to reduce LDL cholesterol and increase HDL cholesterol (resulting in a blood lipid profile that your doctor will like much better), but this may not necessarily affect the risk of heart disease.
Yet another study found that hormone replacement does reduce LDL and increase HDL, but also increases small, dense LDL (the type of LDL most likely to be oxidized). New research has called the benefits of hormone into question because it actually increased a woman’s risk of cardiac problems (yet another point for those who question the link between cholesterol and heart disease in the first place). The epidemiological studies showing a relationship between hormone replacement and lower risk of cardiac disease could simply be reflecting the demographic factors affecting the women who take replacement estrogen.
In other words, estrogen may not be the reason why cholesterol changes during menopause, and if it is, we definitely haven’t figured out the exact relationship yet. It’s also possible that estrogen protects against heart disease for reasons unrelated to the amount of cholesterol in the blood. One study (interesting although it was done in mice, not in humans) found that estrogen reduces atherosclerosis independently from its effects on cholesterol. Specifically, estrogen is an antioxidant, so it reduces the burden of oxidative stress (and thus inflammation). If oxidized LDL really is the culprit behind the cholesterol-heart disease connection, this would make sense as an explanation for women’s lower rates of arterial plaque.
Hormonal changes are one factor common to menstruation, pregnancy, and menopause. But another potential connection is insulin resistance. Insulin resistance is connected with changes in cholesterol numbers (specifically a greater amount of small, dense LDL cholesterol), probably through its effects on the liver. The body’s sensitivity to insulin also changes with the reproductive cycle.
Gestational diabetes is probably the best-known example of this relationship, but insulin sensitivity also varies with the hormonal fluctuations of a normal menstrual cycle. Menopause may also be associated with cholesterol through insulin resistance, and hormone therapy was found to increase insulin sensitivity in postmenopausal women. This may be one reason why the benefits of hormone therapy were mostly associated with the lifestyle of women who tried it, not with the therapy itself: women on hormone therapy tended to be wealthier and more educated, and wealthier and more educated people don’t need to rely on cheap carbs for their meals and have lower rates of metabolic disorders like diabetes. Additionally, the researchers in one study connecting PCOS to cholesterol concluded that the change was more closely related to insulin metabolism and body fat than hormonal fluctuations. The problem could also lie in the consequences of the insulin resistance – insulin metabolism is connected to thyroid health, for example.
To sum it all up, the relationship between women’s natural hormonal changes and cholesterol levels needs a lot more research, preferably research by scientists open-minded enough to consider cholesterol as something other than an obvious evil. But for women worried about their cholesterol levels, these changes do provide several reasons why one test might be higher than another for reasons completely unrelated to diet. For menstruating women, it might be a better option to take two or three tests at different points in your menstrual cycle, to get a more accurate picture. If your pre-Paleo tests were also pre-menopause, and your Paleo numbers are post-menopause, it’s perfectly normal to see a rise in cholesterol, and it’s not because of the egg yolks.
Starvation and Overexercise
Anorexic patients are also well known to have high levels of cholesterol, despite usually having a very low intake of dietary cholesterol. In particular, anorexics who also binged and purged had notably high blood lipids. One study found that the relationship was not very significant, but the study also used women taking hormonal birth control, which could have skewed the results.
Starvation does affect the levels of estrogen and other hormones in women (one reason why anorexics lose their periods), but high cholesterol is a known effect of starvation in people of both sexes, so something besides estrogen must be driving it. Possibly, it has to do with the effect of starvation in downregulating the thyroid (which can raise cholesterol levels; see the section on hypothyroidism above). However, there are also significant differences between anorexia and hypothyroidism, so thyroid problems are unlikely to be the full explanation.
Suggesting that starvation can raise cholesterol on Paleo isn’t meant to imply that Paleo itself is an eating disorder. It isn’t. But many people do actually struggle to get enough calories without refined grains, especially as they’re first getting used to a Paleo diet. And the health-conscious people who are attracted to Paleo in the first place are also more likely to develop eating disorders or overexercise their bodies into a state of starvation. In this case, the solution is to treat the eating disorder, and the high cholesterol will disappear on its own.
Rapid Weight Loss and Fatty Liver Disease
High blood cholesterol can also be a detox symptom from the rapid weight loss many people experience on Paleo. In this case, high cholesterol is actually a sign that your body is healing from the metabolic damage of the modern diet, not a warning that something is going wrong.
The reason that this healing process involves higher levels of cholesterol in the blood is that it’s removing them from the liver. The modern diet is a huge contributor to a disease called non-Alcoholic Fatty Liver Disease (NAFLD), which is an accumulation of excess fat around the liver. This prevents the liver from working properly and can cause serious systemic damage if it isn’t treated, but the early stages are often unrecognized, so many people may not even know they have it.
Fatty liver develops under the influence of several factors, but most important is a deficiency of choline, a vital nutrient ironically found in cholesterol-rich foods like liver and egg yolks. After switching to a Paleo diet, losing their fear of delicious treats like fried eggs and liver pate, and experimenting with more organ meats in the diet, many people start to heal from fatty liver. This is very healthy in the long run, but it does mean that all the stored fat from the liver has to go somewhere, and during the initial detoxification period, that “somewhere” is the bloodstream.
To add to this, people with fatty liver are often also overweight, and the switch to Paleo helps them lose the extra pounds. This also brings the stored lipids from body fat deposits out into the bloodstream as part of a detoxification process. But this isn’t a permanent situation, and it doesn’t indicate a problem. It’s actually good, because it shows that the body is healing from the damage of the modern diet. So if you’re still in the process of losing weight, or if you’ve just recently transitioned to Paleo, higher cholesterol numbers might not actually be as alarming as they first appear. To get an accurate reading, it’s better to wait at least 6 months after reaching a stable weight for a blood lipid test.
Familial hypercholesterolemia (FH) is the elephant in the Paleo room, because it accounts for many of the people who do see a correlation between dietary cholesterol and blood cholesterol. These people are in the minority, but they do exist. People with FH have a genetic mutation that prevents them from removing LDL cholesterol from circulation in the blood. For these people, a Paleo diet will lead to much higher blood cholesterol, because they can’t metabolize the cholesterol normally.
In the case of FH, there are no easy answers. A lower cholesterol diet might be necessary for people with FH but there are actually ways to do this without abandoning Paleo principles. Eating more fat from olive oil and other monounsaturated fats, including a higher percentage of calories from safe starches, and cutting down on animal fats can still yield a basically Paleo diet.
Other potential therapies include supplementation with thyroid hormones or iodine (to increase the activity of the receptors removing LDL cholesterol from the blood) and taking antioxidants (to prevent the LDL in the blood from oxidizing), but these aren’t good subjects for self-experimentation. In the absence of a safe, non-invasive therapy, finding an open-minded doctor willing to work specifically with you instead of writing an automatic statin prescription is the best way to manage FH.
Cholesterol: The Big Picture
If this all seems incredibly complicated and interrelated, that’s because it is. None of these reasons exists in a vacuum, because the body is a complicated system with an enormous number of interconnected parts. Thyroid problems, hormonal fluctuations, starvation, and metabolic diseases like fatty liver are all related, and it’s difficult to pin down one of them as the only problem affecting any particular person. This is also why it’s so silly to focus only on lowering cholesterol itself with statins, when there are so many other contributing factors.
Any number of lifestyle factors, like stress, micronutrient intake, or even leaky gut, can also influence all of these potential causes of high cholesterol, and explaining the links among them would probably fill several books. But what should be absolutely clear is that a diet higher in cholesterol isn’t the only factor contributing to higher levels of blood lipids, and that increased cholesterol isn’t an automatic reason to reach for the panic button. Whether high cholesterol is nothing but a symptom or whether it’s a victim of oxidation in the bloodstream, the problem is not one of any particular macro-or micronutrient, but rather of overall, big-picture health status.
From the Paleo perspective, this means that the logical response to high cholesterol is to find out what’s really behind it, and take action (or not) accordingly, not to reflexively focus on the cholesterol itself.
That said, convincing your doctor of this might be a lot trickier than convincing yourself. Most doctors are still stuck in the lipid hypothesis, and many will make a serious effort to put a patient with high cholesterol on statins – even though statins show no proven benefit for anyone besides middle-aged men who have already had one cardiac event. Rather than attempting to convert a skeptical cardiologist to Paleo wisdom in one office visit, try using the Paleo Physicians Network to find a fat-friendly doctor, or asking for a plaque scan to get a more accurate idea of your own risk.
For some more self-education, there are also a lot of great online resources that you don’t need an appointment to use. Chris Kresser has a great series of posts on heart disease and cholesterol, and Chris Masterjohn’s blog at Cholesterol and Health is a gold mine of resources. Educating yourself first, and then finding a doctor willing to work with you, is the best way to keep enjoying the benefits of Paleo without worrying about your cholesterol numbers.