Q & A

Q & A

This page as an open thread for reader questions, especially questions about personal health concerns.

I am putting this page up as a way to share knowledge — my knowledge with questioners, but also so that others with similar concerns can read the conversation, and readers with relevant knowledge can chip in with their own thoughts.

Please keep in mind that I can’t research questions in any depth, so my answers should be considered tentative, incomplete, and subject to later correction. Also, I am not a doctor, and nothing I say should be construed as a substitute for medical diagnosis and treatment. I am only sharing opinions about disease origins and general therapeutic strategies which may or may not be applicable in any given case.

To get the page started, I’ll put up a few questions from recent emails. Here is an index by disease, with clickable links:

And here are my answers.

Chronic Lymphocytic Leukemia (CLL)


Been following your work on the PHD before the publication of the book and commented on my CLL and the usefulness of Vitamin D once on your blog and you responded to keep an eye on my Vitamin K intake, which I do now.. Am fortunate in a way to have my form of CLL as it indolent which gives me the opportunity to experiment without the pressure of undergoing conventional treatment. The PHD, I think, is helpful in this regard.

Wonder if you could point anything out to me that may be useful. Anything at all. And I will be happy to share with you my results.

Surely you know of the helpfulness of green tea with CLL. You may not be familiar with research that points out that those with low levels of Vitamin D need treatment for CLL far sooner than those with elevated levels.

Feel strongly that your version of a ketogenic diet would be helpful but also feel I need some direction in this area. Do you have any suggestions?

Warmest Regards,


Hi A,

I remember your comment, thanks for writing back. I’m glad you’re enjoying our diet and wish you the best.

Thanks for the tips about green tea and vitamin D. Neither one surprises me.

Most likely CLL is caused by a viral infection. So enhancing viral immunity is probably a good idea. Good strategies may include: (1) low-protein dieting, which inhibits viral reproduction and can promote autophagy; (2) maintaining high vitamin D levels; and (3) intermittent fasting, which promotes autophagy.

Some food compounds have been reported to have antiviral effects. An example is green tea catechins, eg http://pmid.us/16137775, http://pmid.us/18313149, and http://pmid.us/18363746, and this could be why green tea is helpful against cancers, http://pmid.us/21595018, which are usually viral in origin.

I might search Pubmed for herbs and spices with antiviral effects, and use them abundantly in cooking, along with antiviral foods. Turmeric / curcumin is a good choice, this needs to be taken with black pepper to enter the body. See http://pmid.us/21299124, http://pmid.us/20434445, http://pmid.us/20026048.

Coconut oil / lauric acid also has some antiviral properties, so inducing ketosis with coconut oil could benefit you even aside from the ketosis. You could also try monolaurin supplements which may enter the body better and which some people have reported to help viral infections.

You might also try HDL-raising tactics as discussed in this series: HDL and Immunity, April 12; HDL: Higher is Good, But is Highest Best?, April 14; How to Raise HDL, April 20.

Another possible tactic is high-dose riboflavin with UV exposure on the eyes. This requires going outdoors at midday and not wearing glasses or contact lenses. Riboflavin+UV is toxic to blood-borne viruses, and the retina is a location where UV can reach circulating blood cells. Sun exposure will also help you optimize vitamin D.

That’s a few ideas, at some point I’ll do some research to come up with more and do a blog post. Do keep me posted on your results!

Best, Paul

Bloating, acid reflux, anxiety, depression, hypoglycemia, hypothyroidism, fatigue

Just came upon your website and had a question for you. I have had some health concerns for the last four years, bloating, acid reflux, anxiety, depression, hypoglycemia symptoms, female complaints (I am in my forties), thyroid antibodies at 333, weight gain around my middle and too tired to work out like I once did. I used to be fikiiled with energy and great health no depression or anxiety. My doctor thinks these symtoms are all from peri-menopause and wants to treat me with Zoloft.

Needless to say I have tried to avoid the Zoloft. I have tired every avenue out there to cure myself. Most recently the Primal type diet. When I eat no grains or dairy I get horrible hypoglycemia symptoms and don’t feel great like everyone else on a low carb diet. I feel weak and more anxious. Do you think your diet would be easier for me with the addition of rice and potatoes?


Hi G,

Yes, I do think our diet will be better for you. You should eat enough starches to avoid hypoglycemia.

The key thing for you is treating the infections which are consuming so much glucose and making you glucose-deficient if you don’t eat enough carbs. Whatever pathogen(s) this is, it seems to have infected your gut and caused the various gut problems; circulating pathogen-derived toxins and immune cytokines are probably responsible for the anxiety and depression. Hashimoto’s hypothyroidism may be either due to circulating toxins or a thyroid infection.

I would suspect some kind of protozoal or parasitic infection due to the hypoglycemia, but what I really recommend is getting your doctor to have a stool sample analyzed for pathogens. Metametrix has a good test. Once you know what pathogen to treat, and get on a better diet like ours, you should improve quickly.


I am writing on behalf of my mother … We live in Dhaka Bangladesh …

Before her illness, my mom was 105 lbs, 5 feet tall and always 10ft tall in spirit…. When she was diagnosed with Lupus at the age of 30, we were all overwhelmed and out of our depths. My beautiful, athletic mother was in a wheelchair and given 6 months to live….

The doctors has advised her to eat literally nothing, minimum protein (1 small piece of chicken/fish, limited to 20g protein per day), only 2-3 types of vegetable and 2-3 fruits and of course lots of carbs to apparently compensate for her failing KIDNEY and LUPUS. She is on tons of medication, no food except the wrong foods (carbs) and in chronic pain. She currently weighs 139 lbs.

Please advise. — S

Hi S,

I believe lupus is a catch-all diagnosis for a variety of conditions which are probably caused by undiagnosed infections. In the US the infections are usually bacterial. I’ve known several people with diagnosed lupus who were cured by antibiotic treatments – in one case the problem was Lyme disease (Borrelia). I have no idea what the likely pathogens would be in Bangladesh. If she does better on low carb and coconut oil, that indicates bacteria; if she does better on high-carb, that indicates protozoa.

A healthy diet is very important. It is very bad advice to “eat literally nothing,” it is essential to be well nourished. Protein is necessary for healing and immune function, and 20 g/day is too little. Fasting is good, but it should be intermittent – not starvation! She needs healthy fats, more protein, and lots of micronutrients. Eggs, shellfish, seafood, bone broth soups, vegetable soups, and fermented vegetables may all be helpful. Coconut milk is probably good for her. You should basically follow the program in our book.

I would try to put her on a good diet, give her a little time for kidneys and other tissues to heal, and then try antimicrobial medicines. Usually, if they’re not working, then you don’t notice an effect. Any strong effect, good or bad, means they are working. Bad effects mean that pathogens are dying and releasing a lot of toxins as they disintegrate. If this occurs, detox aids (salt, water, and one of cholestyramine/charcoal/bentonite clay; also glutathione supports and vitamin C) will help.

Please stay in touch and let me know how things go.

Best, Paul


Jersie wrote:

I’ve suffered from depression for decades. A few months ago, I decided to try the Dr. Kruse protocol for jumpstarting leptin sensitivity and 2 interesting things happened.

When I went very low carb – below 50 gm -. I had half-day periods where the depression suddenly lifted (something that has rarely happened otherwise). However, I also suffered from darker than normal periods.

I stopped the Dr. Kruse protocol after 6 weeks, and went back to regular paleo (approx. 200 – 300 gm. Carb/day). I’m now generally more depressed than usual, without the good periods.

These changes seem to indicate that I can have an influence on my depression with diet, but not sure what diet to try. Thoughts?

Hi Jersie,

I think your experience on very low carb is diagnostically telling.

I would interpret it this way:

  1. Your depression is caused by an interferon-gamma mediated immune response in the brain, probably caused by a viral or bacterial infection. This leads to tryptophan being directed away from serotonin and toward the kynurenine pathway. So you have a serotonin deficiency and kynurenine excess.
  2. A ketogenic diet is both therapeutic (promotes immunity against bacterial and viral infections) and mood-improving (clears kynurenine).
  3. However, you are at risk for hypoglycemia in the brain (especially if the infection is bacterial) and hypoglycemia causes irritability/anxiety and can aggravate depression.

So the very low-carb diet had mixed effects (ketosis, hypoglycemia).

What I would do is follow our ketogenic diet advice. Eat at least 50 g/day carbs from starches to get sufficient glucose, plus sufficient protein to reach 600 calories/day protein+carb, but add in large amounts of MCT oil or coconut oil. Also, do intermittent fasting – eat all the carbs within an 8-hour window; eat at least half the MCT oil in the 16-hour fasting window.

Once on a good diet, I might experiment with antibiotics to see if they relieve symptoms.

Please let me know how things go.

Leave a comment ?


  1. Hey Paul, NAC is no longer going to be available as a supplement. What can it be replaced with? Maybe R-ALA?

    • You can still get bulk NAC on various sites. I just ordered a couple of pounds for future use. All major sites have already removed it, but do a general search for bulk nac and sites will pop up.

      • Thank you I have followed your advise. But still all expire in 2024. I wonder if Paul can suggest a replacement.
        The fascistas have attacked us from another angle.

  2. Hi Folks,

    I’m a thirty-six year old male in very good health–I’ve been proudly following the PHD for many years. I’ve read that Paul aims for a ferritin level of 50-150 (or 130?) ng/ml, and gives blood regulary every few months. So, is my case healthy? I had my ferrtin tested on 8/15/19 at 54 ng/ml and I retested yesterday, 5/26/21, at 53 ng/ml. I hadn’t given blood in the inteval.

    I’d appreciate anyone’s comments.


    • Hi Nate,

      That either means that you are in perfect health (no inflammation, which would raise ferritin) or that you have a combination of inflammation with an offsetting iron deficiency. As long as you feel healthy and have iron sources such as beef in your diet it is probably the former.

      Best, Paul

  3. Thanks Paul, I really appreciate the reply. I’m reading all your blog articles in chronological order–I’m currently halfway (of course, I’ve read the book.) It’s interesting to see the metamorphosis of the PHD. Let me know if I’m being orthorexic, or when the next Retreat comes up. Thanks, Nate

  4. Hi Paul,

    Would you like to play detective? A good friend has some symptoms and may end up on medication indefinitely.

    For the past 2 months:
    – he’s been having palpitations and arrhythmias,
    – His heart beats slower than normal
    – He has what he describes as “attacks in which I get dizzy, sweat, have a choking sensation and pressure in my chest, and it feels like my heart is going to stop at any moment”.

    About him:
    – 25 y.o. male,
    – Athletic and very muscular,
    – Exercises almost every day,
    – Follows a western standard diet, pretty bad, maybe not terrible.
    – Otherwise, I don’t think he has a too stressful life. No stress at work, no alcohol, no sleep deprivation.
    – His blood test was pretty standard. Just bilirubin a bit higher than normal, but hepatic damage was discarded via ultrasound examination.

    I did my homework :razz:, so following the philosophy of this blog:
    – I suspect my friend is overtraining with respect to his body’s ability to overcome the stress, or relative to his nutritional status.
    – First step would be to put him into the PHD, make sure he doesn’t overexercise, etc., but very unfortunately he won’t make any big change on diet or the like.

    I’ve searched possible nutritional causes of arrhythmias and palpitations, which apparently are:
    – magnesium deficiency,
    – calcium excess,
    – salt deficiency,
    – potassium deficiency or excess,
    – methylation imbalances,
    – or anemia.

    He doesn’t have other symptoms that would raise suspicion. We know he doesn’t have anemia. But we don’t know his electrolytes in blood.

    Any suspicion, advice, hint? I appreciate any help. It’s been only two months, and we may hopefully solve this before further damage is done!


    • Hi Hector,

      I would have him adopt PHD and also get tested or treated for possible parasitic infections, e.g. https://medcrine.com/5-parasites-affecting-the-heart-and-their-manifestations.

      Best, Paul

      • Thanks very much, Paul.

        I elaborated this plan:

        0. He will try to implement PHD as much as possible.

        Then he will soon have an appointment with his doctor. Apart from the specific tests that the doctor deems necessary, he will ask to:

        1. Be tested for parasitic infections,
        2. Be tested for C-reactive protein,
        3. Be tested for Total cholesterol, LDL, HDL, triglycerides,
        4. As per my prior comment, to be tested for electrolytes K, Ca, Na. I’d have included Mg here, but decided not to because (i) the doctor may be reluctant to test for it because it’s not such a mainstream test, (ii) serum Mg is not very sensible to deficiencies, and (iii) he will supplement a (low dosage of) Mg anyway.

        Do you agree with 2, 3, 4? I’d have though that 2 and 3 are very informative, yet he didn’t have those tested.

        Then, he will include some of your recommended supplements — not all due to budget:

        5. Magnesium 200 mg/d
        6. Ascorbic acid 1 g/d
        7. B-complex (I found pills without niacin but cannot avoid folic acid) 1 pill weekly

        Is there any other supplement you consider important for him, such as N-acetyl-cysteine, glycine (if he didn’t make collagen-rich soups), taurine?

        And finally:

        8. He will be wary of overtraining,
        9. He was doing intermittent fasting; I asked him to keep calories towards the morning and light hours, but not to prolong the fast if he feels hunger,
        10. Other general steps that are always health-promoting, such as circadian rhythm entraining, controlling stress, etc.

        I will update in the future to hopefully share good news. Thanks so much.

        Best, Héctor

        • (I recall some other nutrients you mention in your book relative to heart health, such as copper and zinc, but he will have those covered by eating whole food.)

        • For the sake of documenting my post, I mention that in the paleo community it seems like an emphasis of seafood, mainly because of its iodine and omega 3, is recommended for people suffering from palpitations and arrhythmias. He’ll try that too.

  5. What is the best time to practice intermittent fasting? Is it best to skip breakfast or dinner? I have read that eating breakfast can help entrain circadian rhythm, is this true? I prefer to skip breakfast but if there are advantages to skipping dinner I will switch.


    • Hi Shane,

      I know these answer from Paul very well because I have been working in implementing it:

      1. He believes that the best eating window is about 3 hours after dawn, and ends 1 hour before sunset. So e.g. if that was 6 am to 6 pm, that would be 9 am to 5 pm.

      2. He believes skipping breakfast will be harmful *only* if that leads you to eat late in the night. If not, it should be OK. On the other hand, I would say he prefers to move most of the calories towards the morning, and I know he emphasizes this e.g. in obesity (and maybe other conditions strongly affected by circadian-rhythm).

      3. I think he would agree. Again, I recall him saying that moving most calories towards the moon is preferable for circadian rhythms (although notice that technically *moving* calories can be done by *concentrating* calories during lunch and then eat less at dinner, even if you are skipping breakfast). And as I said I think he emphasizes it especially in unhealthy people who would be helped by circadian rhythm therapy. E.g., my mother is obese and once she was able to accomplish it he recommended doing two meals a day by skipping dinner (although I am missing if this is due to other reasons apart from circadian rhythms).

      Also, Seth Roberts discovered that he would tend to wake up about three hours before breakfast. He wrote “To ensure we’re active when food is available, [the food circadian oscillator] wakes us up about three hours earlier. If you usually eat at noon, for example, it will wake you up at 9 am”. Check: https://sethroberts.net/2013/12/11/sleep-summary-of-what-ive-learned/#more-12236

      I would say back in the day Paul was very interested by Seth discoveries (such as face-morning therapy to entrain circadian rhythms) and may have been influenced by some (when it already agreed with the evidence, as Seth Roberts was fascinating but had some weak ideas). The thing is that there is a discrepancy here, and I don’t know why.

      So, according to Seth’s theory we would wake up three hours before breakfast, but Paul recommends waking up about one hour before dawn, and start eating three hours after dawn, which would mean that we eat *four* hours after waking up, not *three*.

      Paul, if you are reading, can you clarify why? Do you think Seth was wrong on this one?


      Finally I’m pasting here two comments from Paul that may be helpful to you.

      [1] On 2016, he said:

      “We recommend having a personal 12 hour “day” that is shifted relative to the sun. This gives you time after work to cook dinner and eat well before the end of day.

      We personally use an 8 am to 8 pm day, 8 pm to 8 am night. On this schedule the best times to eat are between 11 am and 7 pm, the best times to sleep 11 pm to 7 am. Try to obtain most calories in the early afternoon. Try to exercise before eating.

      To implement this, set up bright 5500 K color temperature white lights throughout your home and office (or use a light box such as the one here, http://perfecthealthdiet.com/shop-circadian-rhythms/) and another set of orange-filtered bulbs for use in “night”. Switch to the orange bulbs about 3 hours before your bed time and after all eating and exercise is done.”

      [2] On 2013 (so old comment–he may have refined it), he said that the keys for circadian rhythm are:

      – Getting at least 2 hours per day of sunlight or very bright blue light distributed over a 10-12 hour period. Maintain lights as bright as possible over the rest of the period.
      – Getting 10-12 hours of essentially no blue light exposure; ie use amber light bulbs and f.lux on the computer, or wear blue-blocking amber goggles.
      – Eating meals within or close to the period of bright light exposure.
      – Sleeping at a consistent time and to a natural waking during the period of darkness.
      – Physical activity within the bright day period — preferably 30-40 minutes every day.
      – Social interaction and engagement during the day.


  6. Hi,

    Maybe someone can help me with this doubt:

    I see that milk contains a part of nonprotein nitrogen. In dogs, their milk contain ~7.5% of protein by mass and ~0.05% of nonprotein nitrogen, which accounts to ~4.4% of total nitrogen.

    So, in order to know how much protein-derived energy weaned puppies need, should I take this nonprotein nitrogen into account? As I understand it, yes, as this nonprotein nitrogen spares protein needs. If so, then how should I account for it? Is it as simple as adding 7.5% plus 4.4% so to consider that milk contains ~12% of protein by mass?

  7. Ok, so I see protein can be estimated as total nitrogen * 6.38. The 6.38 is the factor used for milk but will vary depending on the food, see table here: https://en.wikipedia.org/wiki/Kjeldahl_method#Applications

    So 0.055 g of nonprotein nitrogen per 100 g of milk will be equivalent to ~0,35 g of protein.

    The rest of the nitrogen (95,6%) will come from 7,5 g of protein per 100 g of milk, which is ~1.195 g of protein nitrogen.

    My confusion comes from this study [1] in which they state dog’s milk contain by mass 9.47% fat, 7,53% protein, 3,81% sugar, and 146 kcal. Yet they state “protein comprised 31% of milk energy”.

    I would have calculated 9.47*9+7.53*4+3.81*4 = 131 kcal, and 7.53*4/131 = 0.23, so that protein comprises 23% of milk energy, not 31%. Even if they didn’t account for the 0,055 g/100 g of free nitrogen, the difference is minimal, in which case 24% of milk energy would come from protein.

    So I don’t know what I’m missing, or maybe the study from 1984 is using old factors that are not used anymore… but I don’t think so, or then the difference would be brutal! If someone realizes, please do let me know.

    [1] https://pubmed.ncbi.nlm.nih.gov/6726450/

  8. Hi,

    Eric answered some questions by mail, and we are sharing them here for the interest of readers.

    Thank you, Eric, for taking the time to answer these questions, and for always making such enriching contributions and discussions!

    Three clarifications:

    – My post-interview comments will appear in square brackets, as in [this example].

    – My questions have been re-written for clarity, as in the original interview they contained contextual information not relevant now. Eric’s answers remain unchanged.

    – All URLs contain spaces after each dot, otherwise the SPAM filter was activated.

    Q: Are you following the Perfect Health Diet after all these years? What don’t you agree with?

    Yes, I still follow PHD. My main point of disagreement, which you likely know already from reading my comments on Paul’s blog, is that I am more suspicious than Paul is of purified nutrients. So I focus on foods like coconut rather than coconut oil, for example. I try to get all nutrients from food, and take far fewer supplements than PHD recommends — currently just vitamin C (and vitamin D in the winter when sunshine is scarce). I also eat significantly less red meat than Paul advises (although I do not avoid it entirely) — I think red meat is not a health concern, but I acknowledge that the data is sufficiently confusing that I would prefer not to take the risk in case I am wrong.

    [In a later comment, Eric made it clear that he is only talking about red meat, not meat in general.]

    Q: So, in 2017 you said you were implementing a food-only version of the Perfect Health Diet [for context, see: http: //perfecthealthdiet. com/recommended-supplements/comment-page-40/#comment-1758146]. Have there been any changes?

    My main corrections to my earlier comment are as follows:

    – Duck egg yolks are much richer in K2 than chicken egg yolks, and Jarlsberg cheese is much richer in K2 than other cheese. With duck egg yolks and Jarlsberg cheese, you can get K2 from food alone too.

    – I have switched from Pacific oysters to Atlantic oysters. Pacific oysters risk cadmium toxicity if eaten in large quantities; Atlantic oysters do not. Two Atlantic oysters per day (about 25 grams edible portion) provides sufficient zinc.

    – I think I overestimated how much soup stock and seaweed is necessary. I eat a bit less now (more like 2 or 3 sheets of nori, and 10 cups/week of soup stock).

    Q: I also recall that you consulted Paul Jaminet on the optimal amount of fiber. While the book suggests that about 1% of energy from fiber may be optimal [and in recent comment, Paul states 1-2% which is equivalent to 15-30 g of fiber], I think you found a mistake and argued for a higher amount. Can you clarify?

    Yes, 2000 calories of human breast provides the equivalent of about 50 grams of fiber, which I think is optimal.

    Q: Readers of this blog know that saturated fat is healthy, and the safest source of calories for our metabolism, as it does not exhibit the toxicity effects that excess carbohydrate or protein do [although of course any source of excess calories can cause damage, such as oxidative stress]. However, as the microbiota is further studied, some suggest saturated fats may promote populations of harmful bacteria, and that saturated fats are very good at driving endotoxins within the body. How do you think this fits in? [The idea I wanted to express is: Could saturated fat be healthy for our metabolism yet unhealthy for our bacteria, so that there is a practical limit at which saturated fat becomes unhealthy through microbiota-mediated effects?]

    No, I don’t think saturated fat, per se, is a cause for concern. I suggest you take another look at the randomized controlled trials in humans which look at the impact of varying saturated fat on mortality. (These trials are some of the older trials I mentioned in my previous email.) They are discussed in chapter 11 of Paul’s book (starting on page 120 in my edition).

    I would avoid purified nutrients, including purified saturated fat. You may find the following study interesting; it compares biomarkers after eating the same amount of saturated from either butter (purified) or cream (not purified): https: //pubmed. ncbi. nlm. nih. gov/26016870/

    The mechanism here is not clear, but endotoxin transport is a reasonable guess: In cream, saturated fat is enclosed in MFGM, and this presumably prevents endotoxins from dissolving into the saturated fat. Regardless, my takeaway here would be to avoid purified nutrients, not to avoid saturated fat.

    Q: Do you think the pulses that you recommended [or better said, determined to possibly be the least risky if well prepared] can be healthy as a staple? In your comments [for context, see: http: //perfecthealthdiet. com/the-diet/comment-page-16/#comment-1667447] you do mention possible hidden dangers, such as toxins not yet discovered. But could it be that the huge amount of epidemiological data in favor of pulses may make us less suspicious, because if they fail to detect problems, they may not exist or be of small importance? As an example, we have seen that the epidemiological data from the COVID vaccines has made us able to detect side effects that had a very low frequency [in reference to the 1/1000000 risk of a blood clotting disorder with the Johnson and Johnson vaccine].

    For safety of the COVID vaccines, we have data from randomized controlled trials measuring hard endpoints *and* epidemiological data — both of which tell the same story. For safety of pulses, we only have epidemiological data, and so our confidence should be lower.

    If eaten in sufficiently large quantities, pulses could also displace animal foods from the diet, thereby making it more difficult to obtain animal-associated micronutrients.

    Q: Electromagnetic fields (EMF) exposure has been a topic of discussion in the alternative health communities, including a part of the paleo community. Do you think it is a factor affecting health?

    No, I am not aware of any evidence that EMF radiation is an important factor in health.

    Q: Do you agree with Paul advice [for context, see e.g. the Perfect Health Retreat schedule: http: //perfecthealthdiet. com/day-perfect-health-retreat/] that to follow an artificial 12-hour “day” and 12-hour “night” that is shifted relative to the sun [and which you would simulate through blackout curtains, blue and green blocking glasses, healthy and time-appropriate artificial light when needed, etc.] would be the best approach to circadian rhythms?

    I agree with Paul here.

    Q: In the past you recommended a specific blue-free LED light to use at night that had no output below 560 nm [for context, see: http: //perfecthealthdiet. com/shop-circadian-rhythms/#comment-1743357]. In this comment, you mentioned you had a spectrometer with which you measured it, so I assume quality lighting is very relevant to you. However, in your comment you did not mention anything about flickering; do you consider it?

    I do not notice any flickering from these light bulbs.

    Q: …So, I assume that you don’t mind the flickering if its frequency is high enough not to be picked up by, let’s say, a phone slow-motion camera, right?

    Correct. I assume that flickering frequencies too high to notice are not an issue. I also always run light sources on maximum brightness, and in particular never with dimmer switches.

    [I will comment on this for people unfamiliar with flickering. The thing is that most dimmable lights are not actually changing their intensity, but rather altering the time they stay on and off. A possible example is that a light set at 50% is actually flickering on half the time and off half the time, at frequencies that the eyes cannot notice. This is indeed a simplification: the flicker effect depends on the shape of the curve (the change in intensity can be abrupt or sinusoidal as in incandescent), the frequency, and the magnitude of the variation in intensity. Flickering influences health, as you can read in the IEEE Recommended Practice.

    Flickering will be minimized at high brightness in any dimmable screen or bulb, and it will matter if your device uses a PWM system to regulate the brightness (in opposite to a DC dimming system, usually marketed as flicker-free screens, but that indeed are also flickering but at a few orders of magnitude higher frequencies). So, you could set up the screen of your PC to the maximum brightness in order to reduce or avoid flickering, and reduce light output to your liking by software by using programs such as “Pangolin Screen Brightness” or “Iris” (similar to F.lux but with more functions).]

    Q: In addition to the PHD blog–which is now on hiatus due to the Jaminets’ cancer research activity–what other sources of information in the matter of health do you follow nowadays?

    Currently, I do not regularly follow any diet-related sources closely, although I do sometimes check Paul’s blog in case there is interesting discussion or updates. I have already researched diet pretty thoroughly, and successfully solved some chronic health issues by doing so. But at this point, I feel that I have reached the point of diminishing returns. So any time I want to spend improving my own health is probably better spent in other ways, such as on exercise (a task at which I still struggle).

    When I was actively following diet-related sources, the only source I found consistently accurate was Paul’s work. Chris Masterjohn also has some interesting ideas, although I would treat what he says as interesting speculation and worthwhile topics for confirmatory research, not as advice I would necessarily follow.

    Q: How is it possible that the official nutrition recommendations, produced by prestigious institutions full of such intelligent and educated professionals, are so wrong?

    Decades ago, nutrition researchers could conduct randomized controlled trials in humans that lasted long enough to measure hard endpoints. This means randomly assigning the participants to eat different diets for several years to see which group lives longer. We have such experiments testing various dietary interventions, all of which support PHD advice. This includes replacement of animal fats with vegetable oils (shown to be harmful), and increasing whole grain consumption (shown to be probably harmful), and others. Some of these experiments were done in prisons, mental hospitals, or other similar institutional settings, which ensures that the participants have good compliance.

    But today conducting such an experiment would at least be considered unethical, if not entirely illegal.

    So why is academic nutrition science so unreliable? Well, what do you think happens to a scientific field when it becomes illegal to run good quality experiments?

    Who stays in the field, and who switches to another field? You can’t get funding or employment unless you do new research. And when the new research with poor methodology contradicts older good quality research, then what are you going to base your dietary recommendations off of? If you admit the older studies are right, and your new results are wrong, well, then good luck obtaining funding or employment.

    Q: What is your religious stance? Do you believe in God, are you agnostic or atheist?

    No, I do not believe in god or follow any religion. If you are interested in the sorts of philosophical questions that religion tries to answer, I would recommend reading “Good and Real” by Drescher, which I think is approximately correct. I don’t have anything to say about where I think it is wrong (not because I think it is completely correct but because such questions interest me less than practical questions about what to eat).

    Thank you!

    • I’m so appreciative of the knowledge you’ve shared with us.

      I would just like to note that if everything I’ve learned from reading Eric’s comments is correct then Chris Masterjohn has been misinterpreting and misrepresenting a significant amount of data over the past several months.

      Thank you Eric and Hector for making this worthwhile discussion public and for your time! 🙂

      • Hi Alexandra, thank you for your kindness. I can say the same. I feel a huge sense of gratitude to people like Paul and Eric, and other discreet commenters, who share so much selflessly and allowed us to learn such important things. They are among the people who have influenced my life the most for the better, and I’m saying this without the tiniest hint of exaggeration.

    • Hi Eric,

      I don’t know if you ever expressed it, but I’m interested to know why you personally reject supplements (i.e. why you feel suspicious about them).

      A few arguments come to mind, but I don’t know if I’m missing more; and I’d like to know which ones you are more worried about:

      1. Differences in the behavior of isolated or supplemented nutrients versus their natural variants found in the food matrix. For example: lack of other synergistic compounds, possible unexpected effects (such as compounds that in abnormal concentrations may have pharmacological effects), and so on.

      2. Possible errors or frauds: supplements with concentrations much higher or much lower than specified. Contaminants. Undeclared substances. Etcetera.

      3. Residual contaminants (these are unavoidable and there will be traces), e.g. from reaction agents, or from the manufacturing process (solvents, etc.), or from the decomposition of molecules.

      4. Inability to follow instinct in food selection. That is to say, if our diet is made up of natural foods, it is to be expected that we’d feel attraction towards those that contain what we need, and repulsion to those that produce excesses. But if we take nutrients in the form of supplements or pills, this relationship with food is broken.

      5. Conservation conditions. Some vitamins degrade with humidity, heat, light, and you do not know if ideal conditions have been respected before the supplement reaches you.

      6. Poor quality. I assume that in purified molecules there is no such thing as “poor quality” (although a poor quality supplement may contain more contaminants, for example — and of course cheap supplements will use less bioavailable molecules, but this can be prevented by reading the label). But in natural products there is: like fish oil, which is rancid; or fruit powders, which may have been processed aggressively, or are made out of poor quality raw material, or contain yeast, etc.

      7. Additives. Artificial celluloses, silicon dioxide, titanium dioxide, magnesium stearate, and similar substances that are generally used as bulking agents, or to encapsulate, or to improve machinability.


      • I was also wondering about:

        8. Supplements in molecular forms that may differ from the forms present in nature or alter the proportion that is found in a natural diet.

        That is, I assume that real foods contain a diversity of forms, e.g., the same mineral may have many chelates. However, when you supplement e.g. magnesium, you typically only supplement one form. I wonder if this difference only affects bioavailability, or if it may have other effects as well.

        [For one, I have heard that certain magnesium chelates are better absorbed by the brain, and that intrigues me as that would indeed indicate that we wouldn’t be emulating the magnesium found in natural foods, which may carry (perhaps unknown?) risks. I suppose also that the body is able to ionize and use magnesium as it pleases, so if certain supplemental forms are destined for the brain it is because we are only facilitating the work the body would do itself, not overlapping it (if I’m making myself clear).]

        • I just recalled that the book discusses the two most common forms of selenium: selenomethionine and selenocystheine. The former has potential detrimental effects, so PHD favours selenocystheine (which is naturally found in animal products).

          How do we know that similar issues don’t arise for e.g. the many forms in which magnesium or zinc can be found in supplements? I recall Chris Masterjohn arguing against zinc picolinate, so I’m assuming there is room for debate on these issues. So is this concern legitimate?

      • Hi Hector,

        Your list of reasons seems pretty good. Here are a few of my thoughts, elaborating on your concern #8 and adding two more of my own:

        8. This concern extends to vitamins as well minerals. For example free pantothenic acid basically does not exist in the food supply; it is found near-universally as either part of the coenzyme A or 4′-phosphopantetheine molecules.

        9. Free micronutrients may be accessible to the microbiome at an earlier stage of digestion than their food-bound counterparts.

        10. A diet that is missing many known beneficial compounds is likely to also be missing other unknown beneficial compounds. For example the best food sources of pantothenic acid also contain considerable quantities of ergothioneine. If you are supplementing pantothenic acid should you also supplement ergothioneine? This is not one of Paul’s recommended supplements; should it be? How many other things are missing?


  9. Is this diet good for bariatric patients and what supplements do you recommend?

  10. Hi Paul,

    this preprint (not peer reviewed) is doing the social media rounds at the moment… along with comments about Cancer… & TLR4.

    “The BNT162b2 mRNA vaccine against SARS-CoV-2 reprograms both adaptive and innate immune responses”


    I dont pretend to understand any of it.
    As Cancer is being mentioned (along with TLR4), I thought of you.

    When you have a chance, could you take a look please… & comment back.

    Much Appreciated.

  11. Hi Paul

    I believe I read one of your comments in the blog, that was saying the 1lb starches and 1lb meat per day is based on a 2000cal diet, does it mean I would need to increase those if I’m on a 3500cal diet, or just adding the extra fat for the added calories? perhaps breaking down the 3500cal on 50%fat/30%carbs/20%protein?

    thank you

    • Hi Gianluca,

      I would say your basal calories should be roughly covered by the calorie split of 55% fat, 15% protein, and 30% carbohydrate. To do so, generally you want to keep the volume of starch and protein sources equal, as the volume of natural foods generally fit in these proportions. Then, eat vegetables and fat sources according to appetite — do keep fat sources around your menus, as egg yolks, avocados, coconut milk, nuts, a bit of oil for cooking, and so on, apart from the fat naturally found in animal foods.

      I would not go beyond 600 calories of proteins per day. Arguments are found in the book. (This is actually implicit in the previous advice.)

      The extra calories spent as a result of exercise should come from carbohydrate; as a rule of thumb, say 300 to 600 calories per hour of exercise.

      Better than keeping an average consumption of calories per day, it is good to overeat during exercise days, and sightly undereat during rest days.

      Finally, alter these ratios according to your personal preference. Don’t feel obliged to do what looks good on paper. E.g. if you feel protein sources start to be unappealing, you will know you are getting too much protein.


      • BTW, I think fruit is also to be scaled by those proportions. Fruit is helpful to replenish collagen for someone who exercises.

      • thanks Hector. If I’m understanding well, to reach my 3000/3500 cal per day then, I should only increase my fat and carbohydrates, which at 30% of energy comes at either at 225 or 260gr of carbs, paraphs with the 260gr on my training days.

        what do you mean by keeping the volume of starch and protein equal? sorry to overloading you with questions, but Paul in the book recommends .5 to 1.5 of meat per day, I have never understood if it is a raw or cooked measure? I also don’t find the protein recommendation specific, as there is a substantial difference in the protein content of 1 lb lean meat vs 1 lb of fatty meat, what do you recommend to count macronutrients?

        I see your comments all over the blog, are you working with Paul?

        • Hi Gianluca,

          I would do this:

          – Calculate your expenditure on rest days (days in which you don’t do intense physical activity). Use the Mifflin St. Jeor equation or similar.

          – Multiply that number by 0.55 (or 55/100) to obtain the fraction of calories that should come from fat, 0.30 for carbohydrates, 0.15 for protein.

          – Convert to grams by dividing fat calories by 9, carbohydrate calories by 4, and protein calories by 4 as well. Those are the grams of each macronutrient that you will need on rest days.

          – For exercising days: per each hour of intense exercise, add 300 to 800 calories from starches and some fruit (or more if you are an elite athlete) depending on your size and intensity of exercise. You could estimate whether to go for the upper limit or the lower limit by being aware of your breathing rhythm, fatigue, and appetite.

          – Once you got the numbers, how do they translate to real food? You must figure out rules of thumb to ease daily life, otherwise, you will get crazy. (Anyways, trying to be too precise would backfire; your preference towards foods is an instinct that will tune-fine your proportions better than you can, as long as your diet is based on foods that resemble those with which your instinct could co-evolve.) If you check the content of starch for tubers, sugar for fruits, and protein for animal foods, you will realize that by eating the same weight of them you’ll achieve these proportions. Take this example: 1 lb of potato, 1 lb of grass-fed meat, and 1 lb of banana would account for 96 g of starch, 56 of sugar, and 100 g of protein. For every 2,000 calories, PHD prescribes 100 g of starch, 50 g of sugar coming from fruit (which accounts for 25 g of fructose), and 50 to 150 g of protein. So, you see that with this rule you can approximate the proportions of the PHD easily. You don’t even need to weigh your food because the density of natural foods is approximately constant; so instead, you do good imagining the liquid volume of your food, and then try to roughly eat the same volume of fruit, starch, and animals. For the fat, eat it according to your hunger.

          When we talk about the weight of foods, we are talking about their raw weight (not cooked). Except for foods that are purchased dry, e.g., rice, in which case you want to measure the weight once cooked.

          You will notice that for some foods, if cooked gently, their raw weight is the same as the cooked weight (e.g., steamed potatoes and most vegetables). I would say meat however can lose about 30-40% of its original weight when cooked; offal will lose about 50% of its weight, and bivalves and octopus will lose even more.


          Let’s imagine we have a 20-year-old male, 70 in, and 175 lb, which on rest days still walks a few kilometers, so that he keeps a light exercise level. The Mifflin St. Jeor equation would estimate expenditure of 2,500 calories. So the caloric split would be 2,500*0.55 = 1375 calories that should come from fat, 2,500*0.30 = 750 calories that should come from carbohydrates, and 2,500*0.15 = 375 calories that should come from protein. This is for the rest days. (I apologize that in my previous comment I said “basal expenditure”, which is not precise, as it can be understood as “Basal Metabolic Rate (BMR)” which is another concept – for this example, BMR would be only 1,810 calories.)

          Now, on active days, let’s imagine he does two hours of intense exercise, which adds about 1,000 calories. So in total he will be eating about 0,75 lb to 1,25 lb of meat, 1,25 lb of tubers, and 1,25 lb of fruit, and some vegetables; plus 2 lb of tubers and fruit on exercising days. He can do so by eating three meals on rest days, but four meals on exercising days. Of course, some people won’t have that much appetite, so they could eat cooked vegetables instead of raw, some rice instead of potatoes, and so on.

          Regarding protein, as per the discussion in the book, there is little reason to eat more than 600 calories a day, at least if some carbohydrate is consumed.

          By the way, vegetables also contain some proteins. When I did my calculations, I think something like 30% of my protein intake came from all other foods besides animals. So, soemone muight think they are obtaining e.g. 100 g of protein if they are only considering meat, but they may be neglecting 10-30 g of protein that adds up from other foods.

          So again, don’t worry too much about being specific. Our appetite for protein is pretty well driven. Yes, you may choose cuts that are lower in protein some days, but you will chose others that are higher in protein other days. If you were continuously eating less protein than you need, you would really fancy a steak. So you can’t really get it too wrong; but even if you did, variability can even be beneficial as it probably exerts a hormetic effect on the body.

          Check some tables of composition of meats in order to get references on how much protein and fat they contain, if that is to help.

          Finally, this all seems much more difficult than it is. But don’t panic. You can use Cron-o-meter or other food- and calorie- tracking tools during a few days to check that you are doing it well. It will train your eye as well, so that you will soon realize that you can make good precisions on the fly.

          If something was still not clear enough let me know.


        • By the way, I do not work with Paul. I am a sometimes-overzealous commentator!

          Hilariously enough, commenting on the blog has served as diagnostic data. As I keep improving my health, I realized I may have a brain infection, as I have an awful hard time concentrating, thinking, and recalling. E.g., I don’t have insulin resistance and I follow the PHD, and I don’t think I have sugar crashes, but I still notice symptoms of hypoglycemia in the brain that cause me to eat more often than I would need to. The mental state is awful. Low serotonin may explain a bunch of other symptoms as well. It is easy to get used to the suffering when you have been sick for many years, but suddenly one day you realize that living like this is NOT normal. And it’s a relief. I was immunosuppressed with drugs for 15 years, and four years ago I was so weak to nearly die (I’ve since been recovering) – this may suggest germs thrived on me during those times.

          Health is tricky in that you have to keep untangling one thing from another. And this extends to remedies as well. For example, if I understood correctly, ketosis would be good for an infection in the brain, and a good strategy might be to eat coconut milk for breakfast and dinner to prolong the effects of autophagy in the brain. But I may have fungal infections as well, and so far I do know I have a fungal dysbiosis, so I can’t have coconut milk yet.

          I’m reading old blog posts and other forums to see what the best plan would be for this issue. I will expose it when I’m done — hope Paul can provide feedback then! 😀


  12. Hi Paul, hi Eric (if you’re around),

    If you had time, what is your general insight about Mendelian randomization studies?

    For context:

    I have started to interpret the scientific evidence myself. I am still in diapers, but I see that everything fits well with the PHD advice.

    However, Mendelian randomization studies have been a stumbling block — it seems that one has to be pretty wise to assess their quality, since they rely on very specific genetic hypotheses and very heavy statistics. (I should mention that it doesn’t seem to be necessary to understand Mendelian studies to interpret nutrition, at least for now; as Eric once explained here, the old studies are often the best, and in any case, the evidence is often redundant before reaching clarity).

    They seem to be called a “natural alternative to randomized clinical trials”, but that seems overly optimistic on several counts. I know nothing about this, but a few arguments come to mind.

    The genome is a network of genes interacting with each other. It is hard to believe that a given gene would affect only one aspect of our biology. Moreover, if a relatively common gene has survived the process of natural selection, it is to be expected that it is because it has interacted favorably with other genes (and of course with the environment; except perhaps for a minority of selfish genes that may favor their own survival). So there must be important cofounding — but I don’t know how common or important that is: enough to make many studies “useless” or not? Maybe enough statistic power can beat the flaws, or not?

    One fact that caught my attention: most blogs and books I have ever read contain little or no mention of Mendelian randomization, including this blog. (At least explicitly; no results are found by searching “Mendelian randomization” or “Mendelian”.)

    Thank you.


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