Three better questions to ask than whether something is natural or synthetic

Key takeaways

• NIH reports that your body absorbs at least 85% of folic acid taken with food but only about half of the folate found naturally in food.
• Lab-made vitamin C is absorbed about as well as the vitamin C in orange juice and broccoli.
• Natural vitamin E is twice as potent per milligram as synthetic, yet a federal task force advises against vitamin E pills for preventing heart disease or cancer.
• From 2013 to 2018, raw milk was linked to 75 U.S. outbreaks, and nearly half of the people sickened were under 20.
• The 2025–2030 Dietary Guidelines say no amount of added sugar is recommended, and they list honey among the added sugars.

In January 1998, the Food and Drug Administration began requiring folic acid in enriched grain products such as many breads and pastas. Folic acid is the lab-made form of folate, a B vitamin¹.

Since then, rates of neural tube defects, serious birth defects of the brain and spine, have fallen by 28%¹. The synthetic form has a real edge here. Your body absorbs at least 85% of folic acid taken with food, but only about half of the folate that occurs naturally in food¹.

Now the reverse story. Two large trials gave beta-carotene pills, made from the orange pigment in carrots and sweet potatoes, to smokers and others at high risk of lung cancer. Instead of protecting their lungs, the pills raised lung cancer rates, by 18% in one trial and 28% in the other². Yet diets rich in fruits and vegetables are linked with lower lung cancer risk².

So which wins, natural or synthetic? In these two stories, a lab-made vitamin helped prevent birth defects, and a plant pigment packed into a pill harmed smokers. The word “natural” didn’t predict either result.

A better test asks three questions. What exactly is in it? How much? And what does the evidence show? Here is how those questions sort out some of the most common natural-versus-synthetic debates.

“Natural” tells you where something came from, not what it does

The federal definition of natural flavor makes the point. Under FDA rules, a natural flavor is an oil, extract, essence or similar product drawn from a plant or animal source. It can also come from heating, roasting, enzymes or fermentation⁶.

Its main role must be flavor, or in the rule’s words, “flavoring rather than nutritional”⁶. An artificial flavor is any flavoring that doesn’t come from those sources⁶.

Notice what the definition covers: the source and the process. It says nothing about safety or nutrition. A natural flavor can be made with enzymes or fermentation in a factory and still qualify⁶. Our article on “natural” food labels covers those rules in depth.

The same logic applies to vitamins. When two molecules are truly identical, your body can’t tell where they came from. When they differ, even slightly, the difference can matter. Vitamins show both cases.

Sometimes they are identical: vitamin C

Vitamin C is ascorbic acid, whether it comes from a lemon or a factory. NIH’s Office of Dietary Supplements (ODS) reports that ascorbic acid in supplements is about as available to the body as the ascorbic acid in orange juice and broccoli³.

What about premium forms? One study compared plain ascorbic acid, a branded form called Ester-C, and ascorbic acid with bioflavonoids, plant compounds sometimes added to vitamin C products. It found no differences in blood levels or in how much the body excreted³.

Those researchers favored plain ascorbic acid, partly because it costs less³. A later study found Ester-C produced the same blood levels but higher levels in white blood cells a day later³. A difference in blood-cell levels is not the same as a health benefit.

Adult men need 90 milligrams a day and women 75, plus 35 more for people who smoke³. The upper limit is 2,000 milligrams a day from food and supplements combined³.

Verdict: a tie. If you pay extra for vitamin C from acerola cherries or rose hips, you’re paying for the source, not a different vitamin.

Sometimes the natural form is stronger, and still no better: vitamin E

Vitamin E is a case where natural and synthetic are not the same thing. Natural vitamin E is listed on labels as d-alpha-tocopherol. Synthetic vitamin E, listed as dl-alpha-tocopherol, is a blend of related forms⁴.

Milligram for milligram, the natural form is about twice as active⁴. That’s why the conversion from international units (IU), an older label measure, depends on the form: 1 IU equals 0.67 milligrams of natural vitamin E or 0.45 milligrams of synthetic⁴. Check for the “d” or “dl” before you compare bottles.

So natural wins? Not where it counts. In the HOPE trial, almost 10,000 people at high risk of heart disease took 400 IU of natural vitamin E daily for four and a half years. They had no fewer cardiovascular events than people on placebo⁴.

In a longer follow-up, the vitamin E group was 13% more likely to develop heart failure and 21% more likely to be hospitalized for it⁴.

The synthetic form did no better. In the SELECT trial, 35,533 healthy men aged 50 and older took 400 IU of synthetic vitamin E daily. It did not prevent prostate cancer. In 18 months of follow-up after the pills stopped, the vitamin E group had a 17% higher risk⁴.

Another large trial, the Physicians’ Health Study II, used synthetic vitamin E every other day. It found more strokes caused by bleeding⁴.

In 2022, the U.S. Preventive Services Task Force (USPSTF), an independent expert panel, recommended against vitamin E supplements to prevent heart disease or cancer. It found no net benefit⁵. Large doses can also raise bleeding risk in people taking warfarin or other blood thinners⁴.

Verdict: natural is stronger per milligram, but stronger isn’t better. Neither form earned a place as a heart or cancer preventive. Most adults need 15 milligrams a day⁴.

Sometimes the lab-made form wins: folic acid

ODS uses a unit called dietary folate equivalents (DFE) to account for absorption. One microgram (mcg) DFE equals 1 mcg of food folate, 0.6 mcg of folic acid taken with food, or 0.5 mcg of folic acid on an empty stomach¹. In plain terms, the synthetic form goes nearly twice as far.

That matters most before and during early pregnancy. The Food and Nutrition Board, part of the National Academies, advises anyone who could become pregnant to get 400 mcg of folic acid a day from supplements, fortified foods or both, along with folate from a varied diet¹. The USPSTF also recommends a daily folic acid supplement for people planning or able to become pregnant⁵.

Many supplements now offer “methylfolate,” or 5-MTHF, often marketed as a more natural or active form. ODS says it is absorbed as well as folic acid or better, though there is no official conversion factor yet¹. The 28% drop in neural tube defects since 1998, however, followed fortification with folic acid¹.

More isn’t better here, either. The upper limit for folic acid from supplements and fortified foods is 1,000 mcg a day for adults¹. Large amounts of folate can fix the anemia that a vitamin B12 shortage causes, but not the nerve damage. That is why some experts worry high doses could hide a B12 problem until the harm is permanent¹.

Verdict: synthetic wins on absorption and proof. Methylfolate absorbs at least as well, but the birth-defect evidence comes from folic acid.

Sometimes the whole food beats the pill: beta-carotene

The beta-carotene trials are among the clearest warnings in nutrition science.

In the ATBC study, 29,133 male smokers were assigned to beta-carotene, vitamin E, both or a placebo for five to eight years. Those taking 20 milligrams of beta-carotene a day had 18% more lung cancer, and overall deaths were 8% higher².

In the CARET trial, 18,314 smokers, former smokers and workers exposed to asbestos took beta-carotene plus a form of vitamin A, or a placebo. The trial was stopped early, after about four years. Lung cancer was up 28%, lung cancer deaths up 46% and deaths from all causes up 17%².

Yet in observational studies, which track what people eat without assigning anything, diets high in carotenoids, fruits and vegetables are linked to lower risk of several cancers, including lung cancer². Observational studies can’t prove cause, because people who eat more produce differ in many ways.

Still, the contrast is striking. The foods look protective, while the isolated pigment, in big doses, harmed the people at highest risk.

The Food and Nutrition Board advises against beta-carotene supplements for the general public, except as a vitamin A source for people at risk of deficiency, ODS reports². The USPSTF recommends against them for preventing heart disease or cancer, because the harms outweigh the benefits⁵. Beta-carotene from food has no set upper limit, and the most common effect of eating lots of it is a harmless yellow-orange tint to the skin².

Verdict: whole food.

Raw milk: the natural choice with the bigger risk

Many people choose raw milk because it feels closer to the farm and less processed. Those values deserve respect. The safety evidence, though, points one way.

A 2022 study in the journal Epidemiology & Infection counted 75 U.S. outbreaks linked to unpasteurized milk from 2013 to 2018. They sickened 675 people, sent 98 to the hospital and caused 2 deaths⁷. Nearly half of the people who got sick, 48%, were under 20⁷.

States that allowed raw milk sales had an estimated 3.2 times as many outbreaks as states that banned retail sales⁷. A bacterium called Campylobacter caused about half of the outbreaks⁷.

The Centers for Disease Control and Prevention (CDC) lists germs found in raw milk, including E. coli, Listeria, Salmonella and Brucella. Children under 5, adults over 65, pregnant women and people with weakened immune systems face higher risk⁸.

Good farm practices lower contamination but can’t guarantee safe milk, the CDC says⁸. It also advises against drinking raw milk carrying H5N1 bird flu virus in hopes of building immunity⁸.

What about nutrition? The FDA reports that pasteurization kills disease-causing germs without significantly lowering milk’s nutritional quality⁹.

Heating leaves the protein quality unchanged. Milk’s main vitamins, including riboflavin and vitamins B6 and B12, survive heat well, and milk was never a meaningful source of vitamin C⁹. In the CDC’s view, pasteurized milk gives you the same nutrition, minus the germs⁸.

Raw milk also isn’t a fix for lactose intolerance, because it contains no lactase, the enzyme that digests milk sugar. Its bacteria aren’t probiotics, the FDA notes, and raw milk can carry germs that make people sick⁹. Federal rules have barred interstate sales of raw milk since 1987, though some states allow sales within their borders¹⁰.

Verdict: pasteurized.

Honey is natural, and it still counts as added sugar

Honey, maple syrup and fruit juice concentrate feel wholesome. Federal nutrition rules treat them like any other added sugar.

The FDA’s definition of added sugars includes sugars sold as such, like a jar of honey or a bottle of maple syrup¹¹. The 2025–2030 Dietary Guidelines for Americans, released by HHS and USDA on January 7, 2026¹³, list honey and fruit juice concentrate among the names added sugars go by¹².

The new guidelines take a hard line. They state that “no amount of added sugars or non-nutritive sweeteners is recommended”¹². They say a single meal should contain no more than 10 grams of added sugars, and they advise avoiding added sugars in infancy and early childhood¹².

Fruit is different. The guidelines say the sugars that occur naturally in fruit and plain milk are not considered added sugars, and they urge you to eat fruits in their original form¹². They also advise limiting 100% juice or diluting it with water¹².

Verdict: honey and table sugar are in the same category. Whole fruit wins.

A verdict table and a three-question test

Comparison	Verdict	Why
Vitamin C: lab-made vs. from food	Tie	Same molecule, absorbed about equally3
Folate: folic acid vs. food folate	Synthetic absorbs better	About 85% absorbed with food vs. about 50%1
Vitamin E: natural vs. synthetic	Natural is stronger; neither prevents heart disease	Twice the activity per milligram, no net benefit45
Beta-carotene: food vs. pills	Whole food	Pills raised lung cancer in smokers25
Milk: raw vs. pasteurized	Pasteurized	Same nutrition without raw milk’s germs89
Honey vs. table sugar	Same category	Both count as added sugar1112
Whole fruit vs. juice	Whole fruit	Guidelines advise limiting or diluting juice12
Natural vs. artificial flavor	Tells you the source only	The definition is about origin and process6

Use these three questions on any product, natural or not:

1. What exactly is in it? Look for the specific form, such as d-alpha or dl-alpha tocopherol, folic acid or methylfolate. “Natural” alone tells you only the source.
2. How much? Compare the dose with the daily need and the upper limit, both listed on NIH fact sheets. A stronger form or bigger dose is not automatically safer.
3. What does the evidence show? Look for human trials that measured outcomes you care about, not just lab results or tradition. Ask who should avoid it and what it interacts with.

One more check: is the product what it claims? The National Center for Complementary and Integrative Health (NCCIH) warns that words like “standardized,” “verified” or “certified” on a supplement don’t guarantee its quality or consistency¹⁴. The same agency reminds readers that natural doesn’t necessarily mean safe¹⁴.

This test fits natural-health values. Wanting whole foods, fewer additives and products that respect the body is sound, and much of the evidence above backs it: whole fruit beats juice, and carrots beat beta-carotene pills. The questions simply keep the word “natural” from doing your thinking for you.

What the evidence shows

Claim	Evidence rating	Basis
Lab-made vitamin C works the same as vitamin C from food	Strong evidence	Absorption studies summarized by NIH3
Folic acid helps prevent neural tube defects	Strong evidence	National fortification data and expert advice15
Vitamin E pills prevent heart disease or cancer	Evidence says no, or unsafe	Large trials of both forms; USPSTF review45
Beta-carotene pills protect smokers’ lungs	Evidence says no, or unsafe	Two large trials found more lung cancer2
Diets rich in fruits and vegetables lower cancer risk	Promising but early	Observational links for several cancers, none for some others2
Raw milk is more nutritious than pasteurized	Evidence says no, or unsafe	FDA review of nutrient studies9
Raw milk carries a higher risk of serious infection	Strong evidence	National outbreak data78

If a supplement makes you sick, tell your clinician and report it through the federal Safety Reporting Portal at safetyreporting.hhs.gov¹⁵. Call Poison Control at 1-800-222-1222 if a child swallows vitamins or other supplements. Seek medical care quickly for severe or bloody diarrhea after drinking raw milk, especially in a child.

Questions readers ask

The bottom line

“Natural” is a fine place to start and a poor place to stop. In these comparisons, the lab-made form won once, with folic acid, and tied once, with vitamin C. The natural option won when it meant real food, such as fruit and vegetables over pills and juice, and lost when it meant skipping a proven safety step like pasteurization.

Neither “natural” nor “synthetic” decides the outcome. Contents, dose and evidence do. Ask the three questions every time, and you’ll keep the best of natural living while avoiding the cases where nature’s version is weaker, riskier or no different at all.

Related reading

• Why “natural” on a food label guarantees almost nothing
• Most health products aren’t scams, but many just haven’t been proven
• How to judge a cup of herbal tea, which is gentle but not automatically harmless
• Third-party tested says what’s in the bottle, not that it works
• The supplement math that changes which bottle wins

Sources

1. NIH Office of Dietary Supplements. “Folate: Fact Sheet for Health Professionals.” National Institutes of Health. ods.od.nih.gov
2. NIH Office of Dietary Supplements. “Vitamin A and Carotenoids: Fact Sheet for Health Professionals.” National Institutes of Health, 2025. ods.od.nih.gov
3. NIH Office of Dietary Supplements. “Vitamin C: Fact Sheet for Health Professionals.” National Institutes of Health, 2025. ods.od.nih.gov
4. NIH Office of Dietary Supplements. “Vitamin E: Fact Sheet for Health Professionals.” National Institutes of Health, 2021. ods.od.nih.gov
5. U.S. Preventive Services Task Force. “Vitamin, Mineral, and Multivitamin Supplementation to Prevent Cardiovascular Disease and Cancer: Final Recommendation Statement.” USPSTF, 2022. uspreventiveservicestaskforce.org
6. Electronic Code of Federal Regulations. “21 CFR 101.22: Foods; Labeling of Spices, Flavorings, Colorings and Chemical Preservatives.” eCFR, current as of October 2026. ecfr.gov
7. Koski L, Kisselburgh H, Landsman L, et al. “Foodborne Illness Outbreaks Linked to Unpasteurised Milk and Relationship to Changes in State Laws, United States, 1998–2018.” Epidemiology & Infection, 2022;150:e183. cambridge.org
8. Centers for Disease Control and Prevention. “Raw Milk.” CDC, 2025. cdc.gov
9. U.S. Food and Drug Administration. “Raw Milk Misconceptions and the Danger of Raw Milk Consumption.” FDA. fda.gov
10. U.S. Food and Drug Administration. “Raw Milk Questions and Answers.” FDA. fda.gov
11. U.S. Food and Drug Administration. “FDA Considering Revised Approach to Declaration of Added Sugars on Pure Maple Syrup and Pure Honey.” FDA Constituent Update, 2018. fda.gov
12. U.S. Department of Health and Human Services and U.S. Department of Agriculture. “Dietary Guidelines for Americans, 2025–2030.” January 2026. cdn.realfood.gov
13. ADA News. “HHS, USDA Release 2025-2030 Dietary Guidelines.” American Dental Association, 2026. adanews.ada.org
14. National Center for Complementary and Integrative Health. “5 Tips: What Consumers Need To Know About Dietary Supplements.” NIH. nccih.nih.gov
15. U.S. Food and Drug Administration. “How to Report a Non-Emergency.” FDA. fda.gov