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Liver is not only the richest source of ready-made vitamin A, but a true nutritional powerhouse. Steamed carrots and pumpkin are also excellent sources of vitamin A (via their carotenes) and contain numerous other beneficial nutrients. Therefore, its best to meet our vitamin A needs through these foods rather than supplements like vitamin A drops. Unfortunately, many people dislike liver and dont often eat carrots or pumpkin. For them, we recommend our Vitamin A drops, especially if they are also taking Vitamin D3. We recommend taking the same amount of Vitamin A, or at most twice the amount of Vitamin D3, as you are taking. Why retinyl palmitate? Retinol is a ready-made form of vitamin A that is readily absorbed by the body because it doesnt require further conversion. Retinyl palmitate, on the other hand, is virtually the only form of retinol found in food (liver) and is simply a natural compound of palmitic acid, the most abundant fatty acid in the body, with retinol. Approximately 90% of the vitamin A present in the bodies of humans and animals is found in the liver, almost exclusively in the form of retinyl palmitate (and in smaller amounts in compounds with other fatty acids). Therefore, the vitamin A we can obtain through our diet is almost exclusively retinyl palmitate. Why is retinol supplementation beneficial? If you eat almost no liver and only rarely consume carrots or pumpkin, you should take roughly the same amount of retinol supplement as vitamin D3, or even slightly more. With a high carrot consumption (e.g., half a kilo per week) and a consumption of at least 100-200 g of liver per week, vitamin A drops should only be taken as a supplement if vitamin D3 intake is very high (around 8,000-10,000 IU). A daily supplement of 4,000 IU of D3 equates to 28,000 IU per week, so with approximately 100-200 g of liver per week, the 1:1 ratio is already achieved (or by consuming 600 g of carrots per week, or, for example, 100 g of liver + 300 g of carrots per week). With retinol, a weekly or even bi-weekly intake is sufficient; it doesnt need to be taken daily. The crucial point is that within a given timeframe (e.g., within a week), at least as much retinol is ingested as vitamin D3, measured in international units (IU). Slightly higher doses of vitamin A are also not a problem, given that negative effects only occur when retinol levels are 10 times higher than vitamin D3 levels (in the average person, the ratio of vitamin A to D3 is well over 10:1). For those who dont want to do the math, we recommend taking the same amount of vitamin A drops as vitamin D3 supplements. Supplements should therefore also be taken in a 1:1 ratio, as the potentially risky 10:1 ratio is difficult to achieve in this case, even with a large liver diet. (Taking 4000 IU of D3 and 4000 IU of retinol daily would require consuming 1 kg of liver per week to reach a 10:1 ratio.) Therefore, for those who only eat liver a few times a week, a 1:1 supplementation ratio is recommended. If liver is eaten more than twice a week, we recommend, however tedious it may be, calculating your weekly intake of retinol and D3 and aiming for a ratio between 1:1 and 3:1 accordingly. Since supplementing with vitamin A drops shifts the ratio of vitamin A to D3 in favor of vitamin A in cases of existing vitamin D3 deficiency, further supplementation with vitamin A drops can exacerbate a severe D3 deficiency. Several studies have found that this can even have harmful effects. However, this is not the case when vitamin A is taken together with vitamin D3, so even an extremely high dose of vitamin A drops is safe in that case. Interestingly, a 2003 meta-analysis, which analyzed all previous studies on vitamin A supplementation, concluded that neither liver-derived vitamin A (which is retinyl palmitate) nor oil-soluble retinyl palmitate, when taken as a supplement, had any adverse effects. Only the dry form of retinol (retinyl acetate) and the water-soluble or emulsified forms had this effect. The reason for this is unclear, but considering that of all forms of retinol, only retinyl palmitate is a natural form, its not particularly surprising. For this reason, we opted for retinyl palmitate and use it dissolved in MCT oil. Nevertheless, excessive intake of retinyl palmitate is likely also dangerous, as it can also skew the ratio to vitamin D3 levels; however, its crucial to obtain retinol only through natural foods and/or by taking retinyl palmitate, and to avoid retinyl acetate as well as all water-soluble, emulsified, or liposomal forms, as these pose a higher risk according to the aforementioned study. The ideal ratio of retinol to D3: To date, no one can definitively determine the ideal ratio of vitamin A to vitamin D, but some important observations can be made: A vitamin A to D3 ratio of less than 1:1 (i.e., a higher intake of D3) is not a problem, at least up to a certain point. Numerous studies have shown that even a daily intake of at least 10,000 IU of vitamin D3 has a clearly positive long-term effect, without any adverse consequences. The most recent study examined nearly 5,000 people who received 5,000, 10,000, or 20,000 IU of vitamin D3 daily for seven years, without any other supplements. Even among the participants who received 20,000 IU of D3 daily for seven years, no negative changes occurred in their blood counts, not even in their blood calcium levels (which is usually considered the only side effect of vitamin D3, but this proved to be unfounded). On the contrary, several positive changes in the participants health and blood counts were observed. Since the majority of people typically consume less than 5000 IU of vitamin A (including carotenoids), there is obviously no problem with a vitamin A to vitamin D3 ratio of 1:4 (at least, provided there is no retinol deficiency, with high-dose intake of D3). A ratio above 10:1 (with retinol making up the larger share) can, however, be problematic. At least one study examining 72,000 healthcare workers found that subjects with a retinol intake of at least 10,000 IU (roughly half through diet and half through supplements) experienced 48% more pelvic fractures than subjects who only took 3,000 IU of vitamin A (mostly derived from carrots, i.e., carotene). Since vitamin D3 intake, even in people taking a multivitamin and occasionally exposed to direct sunlight, ranges between 500 and 2,000 IU, the ratio in the group with the higher fracture rate must have been between 10:1 and 40:1. A ratio up to 10:1 therefore appears to be safe (at least in cases of mild vitamin D3 deficiency). The following section delves into some theory: From an evolutionary perspective, a ratio of nearly 1:1 seems optimal, because in people who regularly spend time in the sun, the skins vitamin D3 production stabilizes at a synthesis of approximately 4000 IU of vitamin D3 daily. This means that our ancestors in Africa were able to absorb roughly 4000 IU of D3 daily. For three million years, the ancestors of modern humans were primarily hunter-gatherers and scavengers, their diet consisting of bone marrow, brain, bones, insects, mollusks, seafood/algae/seaweed, and of course, fruits, vegetables, and roots. For predators, the best part of prey is the liver (predators, unlike humans, are able to excrete retinol, so they cannot overdose on it). However, humans only began hunting 100,000 to 200,000 years ago. If we calculate what proportion of the calories obtained from consuming the whole animal are derived from its liver and kidneys, we find that with a daily intake of 2000-3000 kcal, if the animal is eaten from nose to tail, approximately 2000 IU of retinol can be ingested daily (apart from the liver and kidneys, no other part of the animal contains significant amounts of retinol). A 1:1 ratio would require 4000 IU of retinol. However, since plant-based foods also contain carotenoids from which retinol can be synthesized, the ratio can be higher than 1:1 (with a higher amount of vitamin A). However, if one only considers pre-formed, ready-made vitamin A (retinol), even a 1:1 ratio is hardly achievable, let alone surpassed – unless one had discarded the majority of animal products and hunted animals solely for their livers, which is unlikely… For those interested in learning more, we recommend Paul and Shou-Ching Jaminets book *Perfect Health Diet* and the Weston Price Foundations article on this topic: https://www.westonaprice.org/health-topics/abcs-of-nutrition/vitamin-a-on-trial-does-vitamin-a-cause-osteoporosis/ In our opinion, aiming for a 1:1 ratio of retinol to vitamin D3 is generally advisable. We have not included the intake of carotenoids here – although these should also be consumed in abundance if more retinol is needed, as retinol can be produced from carotene. However, a ratio between 1:4 and 10:1 is probably also appropriate, especially if sufficient amounts of vitamin K (K1+K2) and magnesium are also ingested. Vitamin K, for example, can limit the harmful effects of excessive vitamin D3 even without vitamin A drops. These substances not only counteract each others side effects but also enhance each others positive effects.
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