- The long-standing debate
- Differences between synthetic, “natural”, and plant-based vitamins
- Animal research
- Why are synthetic/isolated vitamers harmful?
- The Supplement Facts panel: distinguish harmful from healthy
- Best practices for obtaining the health benefits from vitamins
- The top recommended products
This article will focus on provitamin A (carotenoids) and vitamin E (tocochromanols), and reveal the critical differences between synthetic, “natural”, and plant-based forms.
In this article, you will learn these 3 valuable lessons:
- Which types of vitamins increase the risk of cancer, stroke, and heart disease: Learn why synthetic, or even so-called “natural” vitamin supplements, can be a threat to your health.
- The critical importance of mixed vitamers: Learn how a broad-spectrum of vitamers is essential for health and which ones you need the most – carotenoids and tocotrienols.
- Easy tips on interpreting the Supplement Facts panel: Learn how to spot the harmful vitamins in both food and supplements.
Provitamin A and vitamin E are not single substances but are in fact groups of vitamers. (1) Most conventional vitamin supplements only contain a single vitamer, while true plant-extracted supplements retain a broad-spectrum of vitamers. (Figure 1) Broad spectrum vitamers function as harmonious antioxidants, neutralizing the negative effects of free radicals. (2–6) However, once isolated from their natural relatives, single vitamers misbehave as hazardous pro-oxidants. (7) This article will examine the profound implications of this.
Before moving on, let’s review some important terms:
Individual compound that makes up a family of vitamins. (e.g., alpha-tocopherol is a vitamer of the vitamin E family.) (1)
Includes retinoids with biological activity similar to retinol, also known as preformed vitamin A; includes carotenoids (e.g., beta-carotene) that convert to retinoids in the body, also known as provitamin A. (8) In the food supply, there are at least 6 carotenoids (vitamers) with provitamin A activity, and at least 50 other carotenoids with related or supportive functions. (9–11) Note: This article will focus on provitamin A and carotenoids.
Includes tocochromanols that have biological activity similar to alpha-tocopherol. (8) In the vitamin E family, there are at least 13 known vitamers, including tocopherols and tocotrienols which are collectively referred to as tocochromanols. (12, 13)
Created from industrial chemicals; consists of a single isolated vitamer.
Term used by the supplement industry for vitamins that match the chemical structure of vitamins found in nature. However, most “natural vitamins” are more closely related to synthetic vitamins than plant-based vitamins due to chemical processing into a single isolated vitamer. (13)
Extracted from fruits, vegetables, herbs, fungi, and other natural sources; retains the chemical structure and chemical diversity of vitamins and phytonutrients found in nature.
Any substance that delays, prevents or removes damage from free radicals, which may slow the progression of aging and disease. (2) Practically all vitamers play a role as an antioxidant, but not all antioxidants are vitamers. (2–6)
The long-standing debate
For the past century, the belief that plant-based food can be replaced by a short list of chemicals has misguided researchers, physicians, and consumers alike. (14–16)
In 1962, researchers at the Stanford Research Institute attempted to match the natural composition of broccoli to create “synthetic broccoli” with 48 different ingredients including vitamins, minerals, amino acids, cellulose, glucose, and a small bit of vegetable oil. (17) Guinea pigs were fed the synthetic broccoli, and then subjected to gamma-radiation to mimic nuclear fallout. In the synthetic broccoli group, 95% of the guinea pigs died after the radiation exposure, while only 10% died in the group of animals fed real vegetables. (17)
As of 2015, at least 265,000 naturally occurring compounds have been identified and indexed. (18) Thousands of new compounds are added to this list each year. It is estimated that a single vegetable, such as broccoli, may contain over 10,000 unique substances, arranged in an infinitely complex matrix. (14, 19) Such a complex composition explains how 1 g of fresh apple, with only 0.057 mg of vitamin C, provides the same antioxidant protection as 15 mg of synthetic vitamin C. (20) Indeed, the superiority of plant-based vitamins comes from greater chemical diversity, not greater chemical quantity.
But if plant-based vitamins are so vastly superior, why have synthetic/isolated vitamins dominated our fortified foods and dietary supplements for the last 100 years?
To answer this question, let’s go back to the beginning of vitamin research.
A brief history of vitamins
In the 1930s, prior to the introduction of synthetic vitamins, research on vitamins was conducted using plant-based extracts. (15) Much of the early animal research on vitamin E utilized wheat germ oil, which contained not only a rich source of alpha-tocopherol, but also other E vitamers and phytonutrients. (21) In 1938, pure synthetic alpha-tocopherol became available to the research community. (1) Over the next several decades, researchers found that the synthetic vitamin E did not produce the same results as the crude plant-based extracts. (15, 21, 22) Some researchers believed that the “active” component had been missed entirely. (15, 21) Dr. Franklin Bicknell, a proponent for plant-based vitamins, believed that the failure of synthetics could be explained by the absence of the “complete complex” contained in the plant extracts. (22) Unfortunately, not all physicians and researchers acknowledged the unique functions and interdependencies among the different vitamers. (15, 21, 22)
From the 1940s to the 1960s, much of the research on vitamin E focused on finding the most “active” form of vitamin E, so it could be studied independently. (15) The vitamin E family was ranked based on the ability to sustain reproduction in rodents. (23) Once established that alpha-tocopherol had the greatest activity in this bioassay, the other members of the vitamin E family (e.g., tocotrienols) were largely disregarded. (23–25) However, as we will learn in later sections of this article, each vitamer provides unique and symbiotic functions.
Although many early physicians and researchers recognized the superiority of plant-extracted vitamins (e.g., Catalyn®), those who advocated their use in patients were ridiculed by the FDA for prescribing crude, non-standardized treatments. (1, 14, 21, 22, 26–28) In addition, food-extracted vitamins suffered from batch-to-batch variability and a short shelf-life, which made scientific reproducibility difficult for researchers. (21) Eventually, synthetic vitamins became the preferred source due to their consistent potency and widespread availability. (1, 14, 21)
Failure in disease prevention
Throughout the 1980s, many large-scale studies found that populations with high blood levels of carotenoids and tocopherols had a lower risk of cancer, cardiovascular disease, and other chronic diseases. (29–31) Several test-tube and animal studies suggested that beta-carotene and alpha-tocopherol might be the active components for these long-term health benefits. (29, 32–35) The optimism around supplemental vitamins was made clear when Tim Byers et al., with the Center of Disease Control (CDC), made the optimistic statement:
…cancer chemoprevention through supplementation and fortification of the diet with micronutrient antioxidants [vitamins] could become an effective strategy for cancer control before the close of this century.
– Tim Byers
Centers for Disease Control (1992)
By the mid-90s, the first large human clinical trials were published on the effects of synthetic beta-carotene (20 mg/day) and alpha-tocopherol (50 mg/day) on lung cancer and other chronic diseases. (ATBC and CARET) (36, 37) Incidentally, the studies found that beta-carotene supplementation increased the risk of lung cancer and overall mortality, while alpha-tocopherol increased the risk of hemorrhagic stroke. (36, 37) Over the next decade, several more studies on alpha-tocopherol found an increased risk of prostate cancer and all-cause mortality. (38–42)
After two decades of damaging research, the faith in vitamin supplements for disease prevention started to disappear among the research community. In 2015, at the American Association for Cancer Research (AACR) Annual Meeting, Tim Byers retracted from his previous optimism:
We studied thousands of patients for ten years who were taking dietary supplements and placebos… We found that the supplements were actually not beneficial for their health. In fact, some people actually got more cancer while on the vitamins.
– Tim Byers
Colorado Cancer Center (2015)
Unfortunately, journalists, bloggers, and even Tim Byers himself have failed to clarify one key point. The harmful effects from “dietary supplements” and “vitamins” only apply to synthetic and isolated vitamins. (7, 43) As we will learn, “dietary supplements” and “vitamins” cannot be categorically banished. The synthetic and isolated vitamin supplements administered in many publicized human clinical trials differ greatly from the vitamins extracted from fruits and vegetables – as do the health outcomes.
The following sections will highlight those differences.
Differences between synthetic, “natural”, and plant-based vitamins
If single vitamer molecules were examined, we would find that synthetic, “natural”, and plant-based vitamers all share the same molecular structure. (16, 44) This, however, is where the similarity ends. Plant-based vitamin extracts include a diverse mixture of substances; including dozens of closely related vitamers and phytonutrients. (Figure 2) (45–48)
As you will see in the following sections, both synthetic and “natural” vitamin supplements consist of single isolated vitamers, and therefore have similar biological effects and health consequences. Because of this similarity, they can be collectively referred to as isolated vitamins, regardless of their synthetic or “natural” origins.
The compositional differences between synthetic/isolated and plant-based vitamins are compared side-by-side in the tables below.
|Synthetic / Isolated |
beta-carotene, or all-trans-beta-carotene.
mixed carotenoids, or beta-carotene from [plant name].
Synthetic and even “natural” beta-carotene generally contain pure isolated beta-carotene (>98%) with no other vitamers or carotenoids. (16) This form of provitamin A is generally considered harmful.
Plant-based provitamin A retains a broad-spectrum of vitamers (carotenoids) and other phytonutrients. (48) This form of provitamin A is considered healthy and beneficial. An extract of palm fruit (African oil palm) is used as an example below.
|Provitamin A vitamers:|
|Provitamin A vitamers:
|Dosage and effect on health:|
See supplemental data sheet
|Dosage and effect on health:
See supplemental data sheet
Many of the vitamin E products on the market claim to be natural. However, these products are chemically processed to convert all naturally occurring vitamers into pure alpha-tocopherol. (13, 44) There is no known source in nature that contains alpha-tocopherol without other E vitamers, therefore supplement companies selling isolated alpha-tocopherol as “Natural Vitamin E” are mislabeling their products and liable for a potential lawsuit. (49)
|Synthetic / Isolated|
|“Natural” / Isolated|
|Common names: |
dl-alpha-tocopherol, all-rac-alpha-tocopherol, or dl-alpha-tocopheryl esters (acetate, succinate, etc.)
|Common names: |
d-alpha-tocopherol, alpha-tocopherol, or RRR-alpha-tocopherol.
mixed tocochromanols, mixed tocopherols and tocotrienols, or alpha-tocopherol from [plant name].
Synthetic vitamin E contains a mixture of 8 different alpha-tocopherol isomers. (44) However, only the RRR-alpha-tocopherol exists in nature. Therefore, synthetic vitamin E is referred to as a single isolated vitamer. This form of vitamin E is generally considered harmful.
“Natural” vitamin E starts as an extract from soy or sunflower oil and undergoes chemical processing to convert the mixed vitamers into pure alpha-tocopherol. (13, 44) Although the alpha-tocopherol structure is identical to the “natural” form, this type of vitamin E is a single isolated vitamer. This form of vitamin E is generally considered harmful.
True plant-based vitamin E retains at least eight different E vitamers, and dozens of other phytonutrients. (50, 51) This form of vitamin E is considered healthy and beneficial. An extract of palm fruit (African oil palm) is used as an example below.
|Vitamin E vitamers:|
|Vitamin E vitamers:|
|Vitamin E vitamers:
|Dosage and effect on health:|
See supplemental data sheet
|Dosage and effect on health:|
See supplemental data sheet
|Dosage and effect on health:
See supplemental data sheet
The effect of these vitamins on health and disease will be discussed next.
Provitamin A | isolated vs. broad-spectrum
Animal research has found that broad-spectrum carotenoids (palm fruit extract) are effective at preventing the formation of cancerous intestinal lesions in rats, while the single isolated vitamer beta-carotene is not. (52) Another study found that palm fruit based carotenoids can block UV (e.g. sunlight) related damage more effectively than isolated beta-carotene. (53, 54) One interesting study compared the liver protective effects of plant-based carotenoids and isolated beta-carotene. In this study, the mixed plant-based carotenoids provided greater protection against carbon tetrachloride liver poisoning. (55)
Vitamin E | isolated vs. broad-spectrum
In dogs, plant-based vitamin E (wheat germ oil extract) was compared to isolated alpha-tocopherol in the treatment of neurodegenerative disease. (21) It was found that the wheat germ oil extract reversed the neuromuscular symptoms in 84% of the dogs, while the alpha-tocopherol only improved the condition in 14% of the dogs. (21) Another study in dogs found that broad-spectrum vitamin E (palm fruit extract) protected brain cells against stroke-induced injury, while alpha-tocopherol alone was ineffective. (56, 57) Several studies have shown a protective effect of tocotrienols in rat brain cells against oxidative damage, while alpha-tocopherol alone failed to demonstrate a protective effect. (58–60)
In test-tube studies, broad-spectrum E vitamers from palm fruit extract have strong inhibitory effects on the growth of prostate cancer cells, while alpha-tocopherol alone has no effect. (61, 62) Similar results were found in human breast cancer cells, where mixed tocochromanols suppressed the growth of the cancer cells, whereas alpha-tocopherol alone had no effect. (63–65) Interestingly, the E vitamer gamma-tocopherol possesses anti-cancer activities, which are inhibited by excessive alpha-tocopherol. (66) This suggests that different E vitamers not only have synergistic effects, but may also act to counterbalance each other.
In the microscopic roundworm (C. elegans), palm fruit based tocochromanols provided protection against UV irradiation and prevented premature death, while isolated alpha-tocopherol provided no protection. (67)
Provitamin A | isolated vs. broad-spectrum
Supplementation with synthetic beta-carotene has failed to protect against disease, and has instead produced a harmful effect in the majority of studies. (36, 37, 68–73) Yet over 30 observational studies have shown that higher intakes of carotenoids from fruits, vegetables, and other plant foods are strongly associated with a lower risk of cardiovascular disease, cancer, and chronic disease. (12, 74–81)
Note: A side-by-side comparison of these studies can be found in the supplemental data sheet.
Vitamin E | isolated vs. broad-spectrum
Supplementation with isolated alpha-tocopherol has failed to show a benefit, and in several studies, has actually increased the risk of prostate cancer, cardiovascular disease, and death. (36, 38–42, 82–93) In the major human clinical trials that have used “natural” (isolated) alpha-tocopherol (300-800 IU per day), only one study found a reduced risk of heart attack, two found no benefit, and one found a slightly increased risk of fatal heart attack. (40, 82, 90, 94) Thus, regardless of synthetic or natural origins, pure isolated alpha-tocopherol is generally ineffective or harmful. (36, 39–42, 82, 83, 88–91, 94)
On the other hand, there is a strong correlation between higher plant-based vitamin E intake and lower risk of cardiovascular disease and other chronic diseases. (31, 89) In addition, vitamin E supplementation from plant-based sources has never been associated with an increased risk of chronic disease, and instead, has been associated with beneficial and protective effects. (95–103)
Note: A side-by-side comparison of these studies can be found in the supplemental data sheet.
Beneficial, harmful, or neutral?
Plotting the research findings shows consistent differences between isolated vitamers and broad-spectrum plant-based vitamers. The collection of human research shows that isolated vitamers have generally harmful effects, while broad-spectrum plant-based vitamers have generally beneficial effects. (7, 93, 104) (Figure 3)
Therefore, the harmful effect from vitamins is a consequence of vitamin isolation. (35, 105, 106) When vitamins are retained with their naturally occurring mixture of vitamers, they maintain the valuable benefits associated with plant-based foods. (52, 53, 55, 95–103)
Why are synthetic/isolated vitamers harmful?
Research has demonstrated that isolated beta-carotene inflicts oxidative damage to DNA similar to smoking. (107) Accumulation of oxidative damage to the chromosome (e.g., DNA) is known to be a primary contributor to cancer. (108) In contrast, human studies have shown that plant-based carotenoids (which includes beta-carotene) can actually repair and reverse oxidative DNA damage, and is associated with a reduced risk of lung cancer. (109, 110) In addition, successful treatment of advanced stage lung cancer has been achieved with the Gerson Therapy, which includes the intake of 10+ glasses of fresh raw carrot juice per day. (111–113) This equates to about 220 mg (450,000 IU) of beta-carotene per day, which is 7 times greater than the dose used in the ATBC and CARET studies. (36, 37, 114) Thus, even massive amounts of beta-carotene are beneficial if taken with other naturally occurring carotenoids.
The increased risk of cardiovascular disease from isolated vitamin E (alpha-tocopherol) can be largely explained by the increased oxidative damage induced by alpha-tocopherol when given in its isolated form. (7, 115, 116) Cardiovascular disease is perpetuated by oxidative damage to LDL cholesterol. (117, 118) When LDL particles become oxidized, they are deposited within the artery wall and eventually transformed into a hard calcified plaque. (117, 118) When the plaque ruptures, it can cause a heart attack or stroke. (117)
Isolated vitamins are not harmful because of the dose, the population, or the pre-existing health conditions. Rather, isolated vitamins are problematic because they are isolated.
But how do isolated vitamers contribute to disease?
Isolated vitamers deplete other vitamers
In the food supply and conventional dietary supplements, beta-carotene or retinyl palmitate are used to boost the vitamin A value, while alpha-tocopherol is used to boost vitamin E value. This selective fortification with a single vitamer from these major vitamin groups creates nutritional gaps and imbalances. (Figure 4)
To make matters worse, supplementation with single vitamers can actually deplete related vitamers by ramping up the liver enzymes that accelerate the excretion of the entire family of vitamers. (Table 3) (119–122)
|Intake of isolated vitamer||Effect on other vitamers|
|102 mg of isolated beta-carotene per day in adult men and women.||Decreased serum lycopene by 50% after 3 weeks. (123)|
|30 mg of isolated beta-carotene per day in adult men.||Decreased serum lutein by 38% after 6 weeks. (124)|
|30 mg of isolated beta-carotene in adult men.||Decreased plasma alpha-tocopherol levels by 40% after 9 months. (125)|
|1000 mg of isolated alpha-tocopherol in adults.||Decreased other tocopherols in plasma up to 40% after 8 weeks. (120)|
According to the CDC, only about 0.3% of the U.S. population is deficient in retinol, and less than 1% of the population is deficient in alpha-tocopherol, which technically fills the requirement for vitamin A and vitamin E, respectively. (126–128) However, for lesser known vitamers and phytonutrients, there are severe deficiencies in over 95% of the population. For example, the average intake of alpha-carotene is less than 0.4 mg/day, while research suggests 5 mg/day may be ideal for prevention of chronic disease. (126, 129–133) Similarly, the average daily intake of tocotrienols is less than 3 mg/day. (100, 101, 134–138) Yet, research suggests that the ideal intake is near 100 mg/day for brain and cardiovascular health. (25)
Thus, the modern day population is well covered on the “marker” vitamins which have established Recommended Dietary Allowances (RDAs) but is deficient in the relatively unrecognized carotenoids and tocotrienols.
Isolated vitamers increase oxidative damage
The provitamin A and vitamin E family are some of the most important fat soluble antioxidants obtained from the diet. (108) These antioxidants are stored in nearly all cells and tissues of the body, which neutralize free radicals to prevent oxidative damage to surrounding tissue. (Figure 5) (2)
As a part of normal functioning, a single cell in the body produces about 1,000 free radicals per second, and perhaps 100 times more than this in a state of oxidative stress when antioxidant defenses become overwhelmed. (2) Oxidative stress leads to oxidative damage inflicted upon lipids, proteins, and DNA. (2) As discussed in earlier sections, excessive oxidative damage contributes to cancer, cardiovascular disease, and other chronic diseases. (2, 108)
Free radicals must pass through a variety of biological compartments (e.g., mitochondria, cell membrane, etc) and travel across immiscible phases (e.g., oil and water) to be cleared from the body. (105, 139–144) Tunneling free radicals through these various phases requires dozens of antioxidants (vitamers and phytonutrients) to work together in a closely integrated network. (5, 106, 139–142) This antioxidant network forms the free radical transfer chain. (Figure 6) (139–142)
As seen in Figure 6 and Figure 7, coenzyme-Q10, due to its long tail length, grabs free radicals deep within the cell membranes and passes free radicals to the next closest relatives; the carotenoids and tocochromanols. (141, 143–145) A greater variety of antioxidants broadens the “span” of the antioxidant network and helps remove free radicals more efficiently. (146, 147) Indeed, the protection from a single isolated antioxidant (vitamer) is extremely limited. (35, 106, 115, 139, 148) This was highlighted by a study that examined the effects of isolated beta-carotene in human subjects for 4 weeks. (149) The 120 mg/day dose did not provide any additional antioxidant protection than 15 mg/day, suggesting that the antioxidant network was limited by antioxidants other than beta-carotene. (149)
One study found that 100 mg/day of isolated beta-carotene for only 3 weeks actually increased oxidative damage in humans. (148)
But how can an antioxidant actually become a pro-oxidant?
For illustration, it’s helpful to compare the free radical transfer chain to a human bucket brigade that bails out trash from a factory. In a human bucket brigade, if ten buckets dumped into a single bucket, it would quickly overfill the single bucket. (Figure 8) Likewise, if people dropped buckets from the top of a 20 ft ladder, trash would spill everywhere. Thus, when an antioxidant significantly exceeds the capacity of neighboring antioxidants, or cannot effectively connect with other antioxidants, it ultimately becomes a damaging pro-oxidant. (Figure 8) (5, 35, 115, 139, 141, 142, 148, 150)
Naturally, as the variety of antioxidants increases, so does the antioxidant protection. (83, 105, 106, 115) One study found that cholesterol particles (e.g., LDL) are quickly damaged if coenzyme-Q10 becomes depleted, despite being saturated in alpha-tocopherol. (151) However, only one molecule of coenzyme-Q10 (i.e., CoQ-10) was required for every nine molecules of alpha-tocopherol to control oxidative damage. (106, 142) Thus, even trace levels of co-antioxidants (vitamers) can maintain antioxidant protection.
In summary, supplementation with isolated antioxidants (e.g., single vitamers) produces a disconnected, imbalanced, and unstable antioxidant network that increases the risk of cancer, cardiovascular disease, and other chronic diseases. (5, 7, 35, 115, 141, 142)
The Supplement Facts panel: distinguish harmful from healthy
On the Supplement Facts panel, synthetic and isolated vitamins are easily spotted by the listing of a single vitamin compound, especially when no plant or food source for the vitamin is listed. The compound may be found next to the vitamin line, or in the “other ingredients” section. (Figure 9)
True plant-extracted vitamins can be identified by finding the listing of a specific plant source. For example; “Vitamin A (as beta-carotene from carrot extract)” would qualify as plant-based and would naturally contain a broad-spectrum of other carotenoids. (Figure 10)
Be warned, many vitamin supplements on the market, especially multivitamins, claim to be from “whole-foods” but a careful analysis of the Supplement Facts often reveals that these products contain synthetic/isolated vitamins in disguise.
How can companies get away with this?
If you see the yeast Saccharomyces cerevisiae (S. cerevisiae) or the bacteria Lactobacillus bulgaricus (L. Bulgaricus) on the Supplement Facts panel for a particular vitamin, this means that synthetic vitamins were incubated with these microbes in a fermentation process. (152) After the microbes are given a few days to absorb the vitamins, the material is dried, and pressed into tablets. Although these “cultured” vitamins may be more bioavailable than purely synthetic vitamins, they do not contain the same broad spectrum of vitamers found in plant-based vitamins.
Best practices for obtaining the health benefits from vitamins
For the greatest health and longevity, follow these best practices:
- Reduce intake of foods and supplements with synthetic / isolated vitamers: This will help prevent and reverse vitamer dominance caused by isolated vitamers.
- Consume fresh fruits, vegetables, herbs, coffee, and tea: This is important for obtaining a full spectrum of water-soluble and fat-soluble vitamers and phytonutrients. (19, 153)
- Consume plant-based supplements: Carotenoids and tocotrienols are lacking in over 95% of the U.S. population, even after consuming 2-3 servings of vegetables daily. (129, 136, 154) Many B- and K-vitamins may also be difficult to obtain in sufficient quantity from common foods. (155, 156) Therefore, it is recommended to supplement with carotenoids, tocotrienols, and a plant-based multivitamin for full spectrum coverage.
The top recommended products
It can be difficult to find genuine “plant-based” vitamin supplements, so I’ve done the research for you. To see the top brands that met my stringent requirements, just enter your name and email below:
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