Carnivore

Notes:

What little evidence exists for the sustainability of carnivore diets derives from historic reports on Arctic or nomadic societies, clinical case studies, and accounts on nutrition therapy for diabetes mellitus in the preinsulin era c.1920

Using an online survey, we collected self-reported data from respondents who self-identified as following a carnivore diet for a minimum of 6 mo

Weekly or more frequent consumption was reported for organ meat by 42%, and for nonmilk dairy by 72%.

Most participants reported eating 1–3 times daily (differentiation between meals and snacks was not queried), including 16% three times per day, 64% twice per day, and 17% once per day.

Generally, more participants reported choosing cuts of meat with high (61%) or moderate (37%) fat content as opposed to lean cuts (2%).

Reported prevalence of adverse effects or symptoms consistent with nutritional deficiency was generally low, as shown in Supplemental Table 1, and commonly preceded the diet.

Consistent with other low-carbohydrate diet studies (40–45), respondents reported a mixed blood lipid pattern: LDL-cholesterol, a major conventional cardiovascular disease risk factor, was markedly elevated whereas HDL-cholesterol and TG were favorable. However, LDL-cholesterol elevation, when associated with low TG, may reflect large, buoyant lipoprotein particles, possibly comprising a relatively low-risk subtype

Food allergies and sensitivities are common, and predominantly related to plant foods (51). Some plant chemicals may produce adverse effects through other mechanisms, such as lecithin in beans, cyanogenic glycosides in certain seeds, and glycoalkaloids in potatoes. Indeed, >50% of survey participants started the carnivore diet to improve allergic, skin, or autoimmune conditions, or digestive health, and many reported improvements in inflammatory conditions and related symptoms.

dietary intake may be low for vitamins that are typically derived from plant foods (e.g., fruits, vegetables, nuts, seeds, and grains) or from nutritional fortification of staple foods (e.g., milk, juices, cereals, pastas, and other grain products) (52, 53). In addition, often unquantified phytochemicals (e.g.,polyphenols, alkylresorcinols, phytosterols) are largely absent from the diet. Although these phytochemicals do not have DRIs, they have been linked to cardiometabolic benefits (54, 55). In people who eat meat only with exclusion of dairy (∼30% in this survey), calcium intake might also be low, as illustrated by the low intake and negative calcium balance in 2 Arctic explorers (28)

Although essential nutrients can presumably be derived in sufficient amounts from animal foods (34), they are present in less commonly consumed parts of the animal, such as fat and organ meats (vitamins A and D), or bone (calcium), or may be reduced during food preparation (vitamin C)

Whereas meat is more expensive than grains and starchy foods, it may be less expensive on a caloric basis, depending on location and specific comparisons, than fresh fruits and nonstarchy vegetables (59), and cost may be in addition offset by decreased expenditure for diabetes and other medications.

the generalizability of the findings is unknown owing to the existence of selection bias, because individuals who experienced adverse effects or lack of health benefits are likely to have abandoned the diet and would therefore not have been captured in this survey. Adults adhering to a carnivore diet and responding to this online survey represent a special subpopulation with high levels of motivation and other health-related behaviors (e.g., physical activity, consumption of relatively whole, unprocessed foods). Therefore, respondents likely differ from the general population in ways that could influence the effectiveness, practicality, and safety of a carnivore diet.

Thoughts:

This is an epidemiological study, which is the weakest form of scientific evidence. Patients volunteered into the study, so we have healthy patient bias, and we don't see patients who didn't respond well. This was based on food frequency questionnaires, which has issues with patient honesty, recall, etc. Online surveys also have issues with honesty and data integrity.

The increase in LDL may be concerning to some, but my understanding of current literature is that undamaged LDL (as seen in lean mass hyper responders to ketogenic diets) are quite healthy and at very low risk of cardiovascular events. It’s damaged LDL (glycated and oxidized damage) thats the problem.