Dangers of Artificial Vitamins and Minerals

“The topic of vitamins (and trace minerals) is actually larger than the degree of bioavailability. As an example, how do all the wild canids throughout the eons of history manage to thrive and reproduce without ever consuming the first molecule of micronutrient from a commercial source? …All live well without any vitamins added to their diet. Insight to this situation is gained from research done by pioneer vitamin investigators of the 1920s and 1930s. They could not produce a vitamin deficiency unless feeding a diet high in soluble carbohydrates.”

-Dr. Richard Patton (Ruined By Excess, Perfected By Lack: The Paradox Of Pet Nutrition)


Vitamin and mineral supplementation is common in the general population. Not only do we humans take multivitamins daily, but our companion’s pet foods are loaded with a long list of them as well. In our fast paced society, where healthy eating and whole foods often are not the focus, vitamin and mineral supplements are added to “fill in the gaps”. Sadly there is a danger to vitamin and mineral supplementation, reasons too harmful to ignore.


Once World War II ended, vitamin supplements became much more common despite its

“invention” in 1912 (1), a time where food was scarce but nutrients were needed. Today over 1/3 of people use vitamin and mineral supplements (2). In the last decade alone there has been an 81% increase in their use as many consumers assume they are a safe alternative to a balanced diet and the fact that they are easy to obtain.


In 2020 the human supplement market was valued at $140.3 billion (3) covering tens of thousands of products (4). The pet supplement market was valued at $800 million (5) representing 10-33% of dogs and cats that consume a vitamin or mineral supplement (6, 7). In addition, a majority of pet owners use one or more human supplements in their companions home prepared diet or to supplement their already supplemented commercial pet food.

In reality the way drugs move and work in the body differ from humans and animals, even between species of animals, so cross species comparisons can be difficult to make conclusions from (8). That being said, you may notice we refer to a lot of human supplements or studies with human participants throughout this article. While you may not find this applicable, a large majority of supplements used for companion animals are marketed for humans and tested on animals, manufactured by the same companies and given to our companion animals by their owners.


Most people who use vitamin and mineral supplements assume that all supplements are just as safe, contain warning labels (9, 10) and are regulated like medications that you can get at a pharmacy. In addition many correlate the ability of a supplement to perform its job wth great results simply based on personal opinions and assessments, not based on clinical trials or more scientific modes of evaluation (11).


While, due to modern farming and livestock practices including the use of pesticides, fertilizers and

other factors, nutrient content in fruits, veggies (12), livestock and soil (13) is more depleted causing a huge range of bioavailability. While these sources are not as nutritious as they used to be, it is juvenile to assume they are completely devoid of nutrients.

Manufacturers of our companion pet foods like dry food or canned food on the other hand have to add in artificial vitamins and minerals because their products are exposed to high temperatures during processing, most of the available nutrients in fresh ingredients including meat, fruits, vegetables and grains are altered, denatured or destroyed (14). In order to make their product “complete and balanced”, manufacturers then add artificial vitamins and minerals. Other commercial foods available like frozen or freeze dried raw often add nutrients to meet AAFCO standards (15). Manufacturers must either perform expensive feeding trials to prove the product is sufficient as is or add a vitamin premix that is already pre approved (16).

It kind of defeats the purpose of all those whole food ingredients to begin with. It just sounds fancy to state that the companies used real fruits, veggies and “fresh” meats in the food to get you as the owners to purchase the product for your companions. For those that don’t buy a commercial product, it is becoming more commonplace to add artificial vitamin and mineral supplements to raw food diets as well.

TYPES OF VITAMIN AND MINERAL SUPPLEMENTS (2)

Food Cultured

Supplements are “created” via a fermentation process. Similar to fermented products like kefir, these supplements involve the growth of yeast or algae to make the product. The goal in using this method is to create a supplement that is more bioavailable or easier to digest and be utilized by the body as much as possible (17).


While this method may sound great, always be aware that synthetic vitamins can be mixed with food cultured supplements.


Food Based

This type of supplement is a little misleading as it can combine both natural nutrients and synthetic nutrients. The base of the supplement may be a whole food but the overall product is not as it needs to contain fillers and binders to come together. These nutrients tend to be very sensitive when exposed to light, air, heat and changes in pH levels which can render them denatured or even dead(18).


Bacterial Fermentation


This involves genetically modifying bacterial organisms (GMO) that are designed to make a by-product that is then used as a supplement such as some probiotics or prebiotics (19).


Nature-identical Synthetic

While the name is slightly deceiving these supplements are still 100% synthetic and unnatural (20). They are made in a lab setting and only resemble the natural nutrient in that they are molecularly structured the same (21). Note: THIS DOES NOT MEAN THEY ARE THE SAME.


Strictly Synthetic

Similar to Nature-Identical Synthetic supplements these products are also made in a lab setting and while they can be chemically similar they do not resemble what is found in nature at all (22, 23).


SYNTHETIC

Many vitamin and mineral supplements as mentioned above are synthetic. Often they do not come from natural or whole food sources and those that may, can be treated with ethanols, other solvents, originate from tar or petroleum or come from materials that have been radiated to extract the nutrients from the original source (24, 25, 26, 27, 28)

B vitamins are one of the most prevalent vitamins that come from

coal and tar. Supplements derived from these sources are obviously not something natural the body ingests so it is hard and taxing to the body to break down the components of these supplements. Not only are they cancer causing agents, petroleum, coal and tar contain over 10,000 harmful chemicals, only 50% of which have been identified and understood (29).


Unfortunately many health professionals including doctors and veterinarians assume that the body is unable to tell whether a nutrient is natural or synthetic (30). This is untrue.

  1. Particle size of the nutrient is a very important factor for proper utilization. Natural vitamins have small particles, synthetic vitamins do not (31).

  2. Absorption is also based not only on the nutrient individual but how they interact with other nutrients and components in the complex (32).

  3. The physical and chemical form of the nutrient affects its absorption (33).

  4. Structure affects the nutrient for example synthetic vitamins have an isolated crystalline structure or 3-D arrangement whereas natural vitamins do not (24).

Many synthetic vitamins and minerals are also 50-70% less able to perform properly in the body (34, 35) which could be an advantage as the best case scenario is that they will pass right through. No nutrients are absorbed and you just wasted money on pretty packaging with hopeful benefits. That being said, the body DOES have to remove the toxins. It ISN’T as simple as in and out. The liver (32, 36), skin, kidney (38) and spleen are responsible for removing them, overworking these organs, preventing them from doing other jobs they need to do.

On the other end of the spectrum your companion’s body may now be loaded with compounding toxins that are resulting in some serious side effects and long term health concerns (39). Due to the synthetic nature of many vitamins and mineral supplements, these “gap fillers” are actually causing people to live shorter lives. Some studies suggest that supplementation can actually cause cancers (40, 41, 42) kidney failure (43), cardiac arrest (44) and bone fractures (45).


While artificial vitamins and minerals may look molecularly similar or designed like a natural vitamin or mineral they aren’t. It is very hard to recreate what nature has designed. Therefore when created in the lab, vitamin and mineral supplements are often created by isolating and purifying to create the “beneficial” component of the nutrient. These supplements often are different in their structure, how they absorb, are metabolized (39) and their effect on the body. One individual vitamin or mineral is not one single component, they are complexed meaning they are made up of many components including enzymes, buffers, cofactors and other parts that help the body recognize the nutrient, break it down and utilize it within the body (46, 47). If one component is missing, the function can not proceed. This very quickly results in mineral deficiencies (48), disease and long term poor health.

LABELING

How can you tell if a product contains synthetic supplements? If the package states “with added vitamins and minerals” or “natural with added vitamins and minerals” it is NOT a natural product. In fact anything labeled with natural means virtually nothing as the government has no standardized definition for the word “natural” in pet foods or supplements (49).


When it comes to supplements, labeling laws are a moot point. As it stands currently over ⅓ of products do not contain the active ingredient the manufacturer claims and another ⅓ included ingredients that weren’t even listed (50).


Aside from the label, how can you tell if your vitamin or mineral supplement is synthetic and derived from coal, tar or petroleum? It's as simple as placing your product on aluminum foil in the oven at 180 degrees celsius for 10 minutes. If the supplement you put in the oven is now black, bubbly and smells, your supplement definitely was derived from coal, tar or petroleum (39). YUCK!


OTHER SOURCES


We all know Vitamin C is plentiful in fruits, but Ascorbic Acid, the most common form of Vitamin C on the market, is derived from corn products like starch, sugar or rice (51, 52).


Calcium supplements are often from rocks. Rocks contain minerals but obviously carnivores don’t eat

them, but rocks are cheap. Nutrients are inexpensive to produce by manufacturers via these sources (53) As you can imagine though, consuming rocks can cause digestive concerns. The most common form of calcium is calcium carbonate which is the main ingredient in antacid products like Tums. Antacids work by reducing the stomach acid (54) however in the process it prevents the body from being able to properly break down food items so common side effects include constipation, gas, bloating (55) and other digestive concerns (56).



Natural selenium is sourced from organ meats like kidney (57) but can also be found in fish, red meats and eggs (58). Selenium is important for proper thyroid function and reducing the likelihood of mercury toxicity. In addition it is classified as an anti-mutagenic and removes free radicals (59, 60). The synthetic version is sodium selenite which is a toxic inorganic salt, created by combining sodium hydroxide (commonly called lye)(61) and selenous acid which is part of the process to purify industrial copper. The National Institute for Occupational Safety and Health (NIOSH), states “prolonged exposure to sodium selenite may cause paleness, coated tongue, stomach disorders, nervousness, metallic taste and a garlic odor of the breath. Fluid in the abdominal cavity, damage to the liver and spleen and anemia have been reported in animals.” (61)


Synthetic Vitamin D is derived from radiating (the process of using radiation) vegetable oil (62).


Many vitamin and mineral ingredients are sourced from or made in China. China has more than

monopolized the vitamin and mineral supplementation industry (63). 95% of Vitamin C supplements for example are produced in China (64). This country has had many issues with their products containing heavy metals (65) or other harmful contaminants (66). It is also one of the most polluted countries. Not only is their air toxic, but their soil and water that many products are grown in are as well. The 2007 recall of over 150 brands of pet food due to melamine contamination was found to have originated in wheat gluten from China. Hundreds if not thousands of cats and dogs died from health complications sustained while eating these contaminated foods. The damage was so severe in not only the animal industry but human as well that those responsible for the contamination were beheaded as punishment (67). Even if the supplement is not from China consumers have no idea where the ingredients came from as there are no labeling laws regulating or enforcing manufacturers to label country of origin on their products (68).

The following is a list of supplements that are all classified as synthetic (you can find a more complete list here)

  • Vitamin A: Retinyl Palmitate

  • Vitamin B1 (Thiamine): Thiamine Mononitrate, Thiamine Hydrochloride

  • Vitamin B2 (Riboflavin): Riboflavin

  • Pantothenic Acid: Calcium D-Pantothenate

  • Vitamin B6 (Pyridoxine): Pyridoxine Hydrochloride

  • Vitamin B12: Cyanocobalamin

  • PABA (Para-aminobenzoic Acid): Aminobenzoic Acid

  • Folic Acid: Pteroylglutamic Acid

  • Choline: Choline Chloride, Choline Bitartrate

  • Vitamin C (Ascorbic Acid): Ascorbic Acid

  • Vitamin D: Irradiated Ergosteral, Calciferol

  • Vitamin E: dl-alpha tocopherol, dl-alpha tocopherol acetate or succinate

NOTE: The "dl" form of any vitamin is synthetic (69).

Again this is not an exhaustive list of unnatural sources of vitamins and mineral supplements, but you get the idea that cheap and easy is the slogan of this industry.


Dangers of Vitamins and Mineral Supplements


“Synthetic vitamins and other substances are added (to kibble) in an effort to compensate for this nutrient loss. However, these additives create ongoing metabolic stresses that, coupled with the limited ingredient selection and processing of foods, leads to situations in which cellular nutritional status can be compromised, causing tissue malnutrition.”

-Ron Carsten DVM MS, The Benefits of Whole Food Nutrition in Veterinary Medicine,Whole Food Nutrition Journal

Unlike whole food sources, synthetic vitamins are very concentrated sources of nutrients. Many products anticipate to supply higher levels of nutrients than recommended for daily intake. Synthetic fat soluble vitamins such as Vitamin A, D, E and K are stored in fatty tissues and the liver so it is very easy to produce a toxicity. In addition, because many people believe more is better, they use a product or take one in higher doses in the hopes of preventing any illness, disease or condition inadvertently harming their companion (70). In one review of almost 50 clinical trials it was found that synthetic Vitamin A and E that was

consumed at higher levels than what would be found in an appropriate healthy diet (71) actually risked higher rates of death (72, 73, 74). This is often where the worry of too much Vitamin A comes from in a raw diet. This actually originates from information concerning synthetic sources of Vitamin A versus natural sources like liver that is regularly gorged with no problem in the wild. In fact domestic cats and dogs have a great ability to safely consume large amounts of liver. The most common problem with supplements are issues with the liver because it is one of the main organs for toxin removal. Many of these supplements are extremely hard to break down so it heavily taxes the liver and other organs causing inflammation, organ failure or other complications.

Generally speaking “Naturally-occurring whole-food vitamins are not toxic since the vitamin is complexed in its natural whole integral working form, and requires nothing from the body to "build" a vitamin.


Despite the following being a common problem in cats and dogs, high calcium levels, bone loss (75), calcification of the heart (76) and kidneys (77) is an issue due to synthetic Vitamin D. It is almost impossible to get too much natural Vitamin D from whole foods.


One study showed that the synthetic supplement Niacin or Vitamin B3 was correlated with an increased risk of death from any cause (78) and another study showed that over 25,000 people put on Niacin were not any less likely to suffer from heart attacks, strokes, death or other causes of heart problems, but that it increased chances of problems with the liver, infections and internal bleeding (79).


In another study performed on pigs, Vitamin B rendered every subject sterile. (80)

The AAFCO’s “Official Guidelines for Contaminant Levels Permitted in Mineral Feed Ingredients” addresses heavy metal contamination in pet food. Many sources of supplements are derived from the by-products of the metal industry including but not limited to arsenic, cadmium, lead and mercury. Unfortunately the conclusion was that there is not enough information to determine upper safe levels (81). In addition it has been admitted, research was only conducted on one ingredient at a time versus interactions between two or more. When you have a supplement or pet food label with 10+ synthetic supplements, it's very concerning that there are hundreds of possibly dangerous combinations of nutrients in one package that we don’t know about or have researched.


INFORMATION AND THE GENERAL PUBLIC

There is also information lacking on interactions with various pharmaceutical medications not only in studies but those that work at pharmacies like CVS, Walgreens or places that sell supplements such as the grocery store that are not educated enough in these products and their interactions. Many customers assume supplements are natural and safe and take the product not realizing their pets can have side effects and end up in the hospital (82) . This is even more of an issue when providing a supplement with multiple ingredients and combinations of nutrients.


Owners themselves are not educated enough either on the topic, often they make a connection that may not correlate and while trying to fix a problem on their own end up overdosing their companion that would far exceed daily requirements of vitamins or minerals (83). Most owners are not testing their pet’s food to see what nutrient levels are present, understanding their companions' individual needs or taking other factors into account (84). They simply look for the magic pill that is going to “fill the gaps”, ironically treating their companion like the pet food manufacturers that they are trying to avoid.


If these supplements can be so detrimental, why are they on the market or in our pet foods? Simply put, A) due to the high heating/cooking process of commercial pet foods often vitamin and mineral nutrients are destroyed and must be added after the fact B) it’s much cheaper than whole food nutrients and C) there are very loose regulations and enforcement of vitamin and mineral supplements.

REGULATIONS

Most people who use vitamin and mineral supplements assume that all supplements are just as safe and regulated as medications you can get at the pharmacy (85). This includes the requirement for proper labels as well as warning labels.

FDA

Regulations overseeing vitamin and mineral supplements are not heavily enforced. This includes labeling laws. Manufacturers don’t need approval to sell their products and their manufacturing institutions aren’t overseen as strictly as prescription drug manufacturers. Although they are required to test their ingredients they are not required to submit the results to the FDA before being sold (86). Bear in mind the FDA approves ingredients added to food, but this only applies to human consumption NOT for our carnivore companions (87). We must trust the manufacturers that they are being honest, however, we have no idea what our companions may be consuming. A majority of supplements come from outside the USA and of those 1-3% are actually inspected (67).


Vitamin and mineral supplements are NOT drugs therefore they do not require the same regulations, labeling, recording or scrutiny as a pharmaceutical drug. A product classified as a drug has to go through many long term and expensive clinical trials and provide the data to the FDA who will determine if the product is safe and does its job as claimed (88). This evaluation can take about 15 years and cost around $2 billion to get approval (89).


The government does not approve a product for sale, they do not vouch and affirm the safety (90) of the product and they do not require any pros and cons reports. The only time this is required is if the FDA decides the product may need to be removed from the shelves (91). In fact it isn’t until a product is on the shelves, that the FDA's Center for Food Safety and Applied Nutrition (CFSAN) can evaluate the supplements safety and efficacy (92). At this point the FDA can inspect the facility and interview its staff and then send a Warning Letter to request a voluntary recall (meaning it is not required, just highly suggested)(93) of the product if the FDA finds it non-compliant (94). Unfortunately according to a 2015 study of the 15,000+ plus supplement manufacturers, less than 400 are inspected per year. It should also be noted during the process of evaluation in the meantime the product is still allowed to be sold (95).


OTHER GROUPS

The Center for Veterinary Medicine (CVM) is another sector of the FDA and oversees animal food products. They have a process for approval of added ingredients however those generally recognized as safe (GRAS) such as vitamin and mineral supplements don’t fall under this process of approval. Supplements are assumed fine as long as

  1. There is a need for the nutrient

  2. The label states the product is for supplementation only.

  3. The product contains no excessive amounts of nutrients.

  4. The label does not make any disease prevention or treatment claims nor is it misleading in any way.

  5. The product does not pose a health threat to the animal (96).

Other organizations, councils and agents have come and some have gone such as the North American Veterinary Nutraceutical Council (NAVNC) formed in 1996 (96), the American Veterinary Medical Association who developed guidelines also in 1996 and The National Animal Supplement Council (NASC) in 2011 (97) all aimed at overseeing the efficacy, safety, quality etc. of animal supplements. Some of these organizations may provide seals of approval but many have no requirement that the manufacturer authenticate whether the product is effective or provide any research data (96).


The American College of Veterinary Nutrition (ACVN) has no stance on the use of supplements but does state they aren’t needed with a balanced diet (98).


There is also a third party lab called Consumer Laboratory. It is a laboratory that can supply a seal of approval for products labeled correctly. Manufacturers can voluntarily provide products for testing and positive results are posted to the Consumer Lab website for free. However, they do not validate the effectiveness of the supplement (96).

HEALTH CLAIMS


Manufacturers can use Structure/Function wording to make health claims for human supplements, IF there is approved science to back the information. Labels however also need to contain a disclaimer stating the Food and Drug Administration (FDA) "has not evaluated the claim" and that the vitamin or mineral supplement is not intended to "diagnose, treat, cure or prevent any disease" (99)

While labels are not able to make disease or treatment statements without a scientific claim, many manufacturers do, including 55% of websites that sell supplements online (100)

and because oversight is lacking, manufacturers continue to make misleading, false and harmful claims. There are a select few health claims that can be made on calcium supplements concerning bone health as well as selenium and chromium picolinate (101) but this only applies to human supplements not animal supplements (102).

While you would think consumer safety is top priority, legal courts have taken a freedom of speech stance over persecuting misleading, untruthful or otherwise unproven supplement labeling/advertising (103, 104 ,105). It is seen as unconstitutional to censor commercial speech. In 1994 a law, the Dietary Supplement Health and Education Act was in the making to better regulate vitamin and mineral supplements but the industry did not like this and forced a more lenient attitude towards regulations. (106)


In addition, there is a loophole if a product is under evaluation by the FDA. If just one ingredient is changed, the product is no longer the same, even if the ingredient is a close relative of the previous, the allegations and research into the product must start all over again! (107)


Long story short vitamin and mineral supplements are not regulated the same as drugs you require a prescription from a doctor/veterinarian let alone those that you can just pick up over the counter. REPORTING

Unfortunately to even remove the supplement from the shelves it has to be proven the product is dangerous. This is dependent on adverse event reports from owners and doctors or veterinarians which means it requires a “professional” to even acknowledge or connect the event with the use of the product. Furthermore these reports need to be filed with the right agency/organization (108).


Many believe that because adverse events are not being reported to supplement manufacturers that these products are safe. Currently the reporting system for any side effects or adverse events is lacking in the human realm and near non-existent for animal supplements (96, 109). So essentially no one is liable or held responsible if there are problems.

Several barriers to reporting include various systems requiring payment to access information such as the poison control center of the American Society for the Prevention of Cruelty to Animals or require a membership like with the National Animal Supplement Council. There is also little to no information/definitions on appropriate dose, acceptable ingredients or common adverse events (7).

CONCLUSION


Numerous studies have shown that a healthy companion does not benefit from vitamin and mineral supplementation (111, 112, 113, 114), in fact it seems there is no evidence that vitamin and mineral supplements prevent cancer, heart disease (115) or even help increase lifespan (116, 117). Unfortunately more than 50% of clinical trials that were performed were sponsored by those with a vested interest (118). They pushed information showing benefits from taking these products, squeezing out the reports that showed no significant benefits (119). Including those showing benefits of a whole foods diet with some modifications when it came to health concerns (120) .


In reality junk food tastes good, jobs run our lives and people are exhausted so nutrition really is not a top priority and the idea of a “magical pill” that “fills the gaps” is mighty appealing. However these supplements are never intended to take the place of a balanced healthy diet or provide an excuse to eat junk food (121). “The solution to dead food isn’t adding dead chemicals.”


Analysis of clinical data show that appropriate healthy choices including diet, exercise enrichment etc. are highly correlated with positive health. In fact there is no substantial data to show that supplementing does more good then harm (122, 123).

Unfortunately, it can be extremely hard to avoid synthetic vitamins and minerals. Most human food is fortified with “added vitamins and minerals” and almost every single pet food has a nice long list of synthetic nutrients that are added to their products. Although there are some quality supplements out there it can be hard to get honest information as to where nutrients are sourced from or how they are processed. The best that one can do to avoid the dangers and inferiority of supplements is to try their best to consume and provide whole food options. For your companion, a complete diet featuring a variety of meat, organs and bones can provide all the vitamins and mineral nutrients your companions need in wonderful whole food options.

While manufacturers are supposed to test the products for purity, strength, composition etc, they don’t have to share those results with anyone including the FDA. Supplements are considered safe until forced to be proven otherwise. Because supplements are classified differently than drugs they can contain heavy metals, bacteria, illegal or prescription drugs and manufacturers can inappropriately label their products. In addition the manufacturers can set their own standards so the same product from different companies are not truly the same (124) and therefore not easily comparable.

Life is still an infinite mystery that even science hasn’t 100% figured out. While we can experiment, make guesses, test products, it seems still to date only nature can make a cell, plant, animal, mineral, vitamin with all the right components that almost always work seamlessly together.


REFERENCES

  1. Semba RD. The discovery of the vitamins. Int J Vitam Nutr Res. 2012 Oct;82(5):310-5. doi: 10.1024/0300-9831/a000124. PMID: 23798048.

  2. Andrews, Ryan. “All about Where Vitamin Supplements Come From.” Precision Nutrition, 29 Oct. 2021, https://www.precisionnutrition.com/all-about-vitamin-supplements.

  3. "Dietary Supplements Market Size & Trends Report, 2021-2028". Grand View Research. San Francisco, CA. Retrieved 2021-07-30.

  4. "Dietary Supplement Label Database". Office of Dietary Supplements, US National Institutes of Health. 2017.

  5. Daniells, Stephen. “Pet Supplement Sales Surged 21% in 2020: Report.” Nutraingredients, William Reed Ltd, 16 Feb. 2021, https://www.nutraingredients-usa.com/Article/2021/02/16/Pet-supplement-sales-surged-21-in-2020-Report#.

  6. Report PF. Pet Supplements in The U.S., 6th edition. https://www.packagedfacts.com/Pet-Supplements-Edition-10747551/. Published 2016. Accessed April 7, 2019.

  7. “Safety of Dietary Supplements for Horses, Dogs, and Cats.” The National Academy of Sciences, National Research Council, 2008, https://nap.nationalacademies.org/resource/12461/satety_of_dietary_supplements_final.pdf.

  8. Bracken MB. Why animal studies are often poor predictors of human reactions to exposure. J R Soc Med. 2009 Mar;102(3):120-2. doi: 10.1258/jrsm.2008.08k033. PMID: 19297654; PMCID: PMC2746847.

  9. US Government Accountability Office. Dietary Supplements: FDA Should Take Further Actions to Improve Oversight and Consumer Understanding. Washington, DC: US Government Accountability Office; 2009. pp. GAO-09–GAO-250.

  10. Legum JC. The dangers of DSHEA: a case for expanded FDA authority over dietary supplements. J Med Law. 2002;6:103–122.

  11. “Food Supplements Consumer Research - Food Standards Agency.” Food.Gov.Uk, Food Standards Agency, May 2018, https://www.food.gov.uk/sites/default/files/media/document/food-supplements-consumer-research.pdf.

  12. https://journals.ashs.org/hortsci/view/journals/hortsci/44/1/article-p15.xm

  13. Kopittke PM, Dalal RC, Finn D, Menzies NW. Global changes in soil stocks of carbon, nitrogen, phosphorus, and sulphur as influenced by long-term agricultural production. Glob Chang Biol. 2017 Jun;23(6):2509-2519. doi: 10.1111/gcb.13513. Epub 2016 Oct 11. PMID: 27670741.

  14. Belay T, Lambrakis L, Goodgame S, Price A, Kersey J, Shields R. 392 Vitamin Stability in wet pet food Formulation and Production perspective. J Anim Sci. 2018 Dec;96(Suppl 3):155–6. doi: 10.1093/jas/sky404.340. Epub 2018 Dec 7. PMCID: PMC6285782.

  15. “Aafco Dog and Cat Food.” AAFCO, 2014, https://www.aafco.org/portals/0/sitecontent/regulatory/committees/pet-food/reports/pet_food_report_2013_midyear-proposed_revisions_to_aafco_nutrient_profiles.pdf.

  16. Cooke, Narelle. “'Complete and Balanced' and Raw Food Feeding - a Square Peg in a Round Hole? - Guides: Big Dog Pet Foods.” Guides | Big Dog Pet Foods, Big Dog Australia Pty Ltd, https://www.bigdogpetfoods.com/guides/complete-and-balanced-raw-feeding.

  17. Melini F, Melini V, Luziatelli F, Ficca AG, Ruzzi M. Health-Promoting Components in Fermented Foods: An Up-to-Date Systematic Review. Nutrients. 2019 May 27;11(5):1189. doi: 10.3390/nu11051189. PMID: 31137859; PMCID: PMC6567126.

  18. Strumwasser, Stu, and Bakley Smith. “Vitamin & Probiotic Degradation White Paper.” Green Circle Capital, Green Circle Capital Partners LLC, May 2018, https://greencirclecap.com/vitadegradation/.

  19. Revuelta JL, Buey RM, Ledesma-Amaro R, Vandamme EJ. Microbial biotechnology for the synthesis of (pro)vitamins, biopigments and antioxidants: challenges and opportunities. Microb Biotechnol. 2016 Sep;9(5):564-7. doi: 10.1111/1751-7915.12379. Epub 2016 Jul 4. PMID: 27373767; PMCID: PMC4993173.