Do vegans need collagen or animal fat?

The objection

“Skin, joints and bones are built from collagen, and collagen only comes from animals. Some scientists say the body can’t even make enough glycine, collagen’s main building block. There are trials showing collagen supplements improve skin, and animal fat supplies fats that plants can’t, like the omega-3s in fish oil. Vegans must be missing out.”

The answer

A 2023 review puts collagen at about 25 to 30% of all the protein in the human body, and there are no plant sources of it [1], so the objection starts from two true facts. It goes wrong on how the body gets its collagen. The gut breaks dietary protein, collagen included, into amino acids and short peptides, and the blood carries them to the tissues, where they are used to build the body’s own proteins, collagen among them [1].

Glycine fills every third position in the collagen chain, and glycine, proline and hydroxyproline together make up about 57% of collagen’s amino acids, all three of which the body can make [1]. A 2009 estimate built from published metabolic rates suggested that the glycine an adult makes, about 3 g a day, plus the 1.5 to 3 g a day that diets supply, may fall about 10 g a day short of everything a 70 kg adult uses it for, collagen included, and its authors proposed glycine as a supplement [2]. A 2025 review calls glycine conditionally essential, names inadequate protein intake, malnutrition, late pregnancy, diabetes and insulin resistance among the conditions in which a deficiency has been reported, and says well-controlled studies are still needed to show whether high doses help people without a deficit [20].

The 2009 estimate was for adults in general, and the EPIC-Oxford study (2016), which its authors described as the largest of its kind, doesn’t suggest vegans are worse off: vegan men ate less glycine than meat-eaters, 2.61 g against 3.12 g a day, yet had 16% more of it in their blood, which the authors linked in part to soya, a rich source [3]. A blood level is an indirect measure, and the study did not measure collagen itself, but a gap in intake of about half a gram a day is small beside the 10 g shortfall the 2009 estimate proposed [2][3].

Lysine, the essential amino acid that collagen also needs, is where vegans fall behind. The same vegan men ate 44% less of it than the meat-eaters and had 13% less in their blood, while their proline levels were about the same [3]. The study took one blood sample from each of 392 men aged 30 to 49, and its authors noted that it is not known whether differences like these affect health [3]. A 2022 German study of 36 vegans and 36 omnivores aged 30 to 60, women included, found the same pattern, with 25% more glycine and 25% less lysine in the vegans’ blood [19]. Its three-day weighed food records showed only one vegan, a woman, eating less protein and lysine than the World Health Organization’s estimated average requirements, although its authors noted that a few days of records may not reflect usual intake [19]. Lysine is plentiful in beans and other legumes and in quinoa [1], which makes them the foods to lean on in a diet with enough plant protein.

Making collagen properly also takes vitamin C and iron, which the enzymes that stabilise each new collagen molecule both need, and a shortage of either can leave the collagen faulty [1][4]. Vitamin C also promotes the expression of collagen genes [4]. Scurvy, the disease of vitamin C deficiency, shows what happens without it: fragile skin, bleeding gums and wounds that heal poorly [4]. NHS advice, last reviewed in 2020, is that adults aged 19 to 64 need 40 mg a day, every day because the body can’t store it, and that you should be able to get all of it from your daily diet [5]. The NHS says vitamin C is found in a wide variety of fruit and vegetables, and lists oranges, peppers, strawberries, blackcurrants, broccoli, brussels sprouts and potatoes among the good sources [5]. If you take a supplement, less than 1,000 mg a day is unlikely to cause harm, while more can cause stomach pain, diarrhoea and wind [5].

The evidence that cuts hardest against vegans here comes from skin procedures. A 2025 scoping review found eight studies comparing healing in vegans or vegetarians with healing in omnivores, after treatments ranging from laser surgery and focused ultrasound to biopsies and skin grafts, and in seven of them healing was statistically worse in the vegans or vegetarians [16]. The studies compared people who had chosen their own diets, and the review did not establish why healing differed; its authors called for research into the causes and into what the finding could mean for how these patients are assessed before an operation and cared for after it [16]. Until that research is done, anyone vegan facing surgery has good reason to make sure protein, lysine, iron and vitamin C are covered, none of which requires eating collagen.

Do collagen supplements work?

Collagen supplements may ease knee osteoarthritis and help tendons adapt to heavy training, but for skin the evidence is disputed: a 2025 meta-analysis found no benefit in independent or high-quality trials, although a larger one in 2026 found gains in hydration and elasticity. The supplements are extracted from animal tissue such as cow or fish skin [1] and sold on trials showing better skin. The 2025 meta-analysis, of 23 trials with 1,474 participants, found improvements in hydration, elasticity and wrinkles when every trial was pooled, but none in the trials without funding from pharmaceutical companies and no significant effect in the high-quality ones, and its authors concluded that there is no clinical evidence to support collagen supplements for skin ageing [6].

The 2026 meta-analysis pooled 35 trials with 2,534 participants, including several published after 2024 that the earlier review could not include [7]. It found better skin hydration and elasticity on instrument measures and less water lost through the skin, with the elasticity gains taking at least 12 weeks [7]. It also judged the apparent effects on wrinkles, roughness and skin density to be statistical artefacts [7].

A separate re-analysis, published in September 2026, went back to two earlier meta-analyses, from 2021 and 2023, that had reported benefits. It found data from the original trials reported inaccurately and incompatible measures pooled together, and once it accounted for the dose people took, it found no evidence of benefit [8]. In the 2021 meta-analysis, 10 of the 13 elasticity trials were sponsored or run by industry; 4 of those found a significant effect, and none of the 3 independent trials did [8]. The authors of the re-analysis note that an overwhelming share of collagen trials are industry funded or involve authors with commercial ties to collagen makers [8].

The trials for joints look better. A 2025 meta-analysis of 11 randomised trials involving 870 people with knee osteoarthritis found less pain and better function with collagen than with placebo, although results varied widely from trial to trial [17]. A 2026 systematic review of eight small trials, 246 of whose 257 participants were men, concluded that 15 to 30 g of collagen a day, taken with vitamin C, may help tendons grow thicker and stiffer during heavy resistance training, and found that it added nothing to the strength people gained from the training [18]. These trials gave collagen on top of whatever people already ate, so they show it working as a treatment for sore knees or loaded tendons rather than showing that a diet without it falls short.

If collagen supplements do help, one proposed route is signalling. Some collagen survives digestion as short peptides that reach the blood at micromolar levels, and one of them, Pro-Hyp, encourages the growth of fibroblasts [9], the cells that make most of the skin’s collagen [4]. A 2017 review offered this as a partial explanation for the benefits reported in trials [9].

What is vegan collagen?

Products sold as vegan collagen include two very different things, because plants make no collagen of their own [1]. One is the collagen booster, a blend of foods and plant extracts rich in the co-factors the body uses to make its own collagen, such as the grape seed and tomato extracts a 2023 review names, with no collagen in it [1]. A hibiscus extract sold as a plant-based alternative to collagen improved skin hydration, elasticity and wrinkle depth against a placebo over 12 weeks in a 2025 pilot trial of 98 Korean adults, although it was a single trial of an extract from a company that employed one of the authors, the kind of industry-linked evidence the re-analysis above warns about [10][8]. The other kind is real collagen made by yeast, bacteria or plants such as tobacco that have been genetically engineered to produce it [11], and it is made for medical and cosmetic uses [1].

Do you need to eat animal fat?

You don’t need to eat animal fat, because the two fats the body can’t make, linoleic acid (an omega-6) and alpha-linolenic acid (ALA, an omega-3), both come from plants, and the body makes saturated fat and some monounsaturated fats for itself from carbohydrate and protein [12]. Cholesterol, the other thing animal fat is said to supply, is mostly made by the body in the liver [14].

Fat	Can the body make it?	Where a vegan gets it
Linoleic acid (omega-6)	No [12]	Vegetable oils, nuts and seeds [12]
ALA (omega-3)	No [12]	Walnuts, flaxseed and rapeseed oil [13]
EPA and DHA (long-chain omega-3)	From ALA, slowly and in small amounts [13]	Algae oil supplements; the omega-3 in fish comes from algae [13]
Saturated fat	Yes, from carbohydrate and protein [12]	Coconut and palm oil, though UK advice is to limit it [14]

UK advice is to get more omega-3 by eating at least two portions of fish a week, one of them oily [14]. For people who don’t eat fish, the BDA lists walnuts, pumpkin and chia seeds, rapeseed and linseed oils, soya foods and omega-3 fortified foods, and notes that some supplements are made only from algae and suit vegans [13]. Its 2021 fact sheet doesn’t recommend omega-3 supplements for the UK population in general, because evidence of benefit is inconclusive, but suggests about 450 mg of EPA and DHA a day for anyone who chooses one [13]. If you are pregnant or breastfeeding, the answer on pregnancy and breastfeeding covers omega-3. Vegans do have less EPA and DHA in their blood: a 2005 study of 659 British men found lower levels in vegans and vegetarians than in meat-eaters, although the levels were not linked to how long the men had been vegan or vegetarian, which ranged from under a year to over 20 years [15]. Omega-3 without fish covers that choice in more detail.

If you take warfarin, aspirin, clopidogrel or another drug that thins the blood, speak to your GP or pharmacist before starting an omega-3 supplement, algae oil included, because high intakes of EPA and DHA can lengthen bleeding time and the Linus Pauling Institute advises monitoring clotting in people who take both [12]. Don’t change or stop a prescribed medicine without your GP’s advice.

Saturated fat comes mostly from animal foods, including fatty meat, butter, cheese and cream, and among plant foods from palm and coconut oil. UK advice (NHS, 2023) is that eating too much raises LDL cholesterol, which can increase the risk of heart disease and stroke, so men should have no more than 30 g a day and women no more than 20 g, children less, and some of it should be swapped for unsaturated fat [14]. The latest US advice is muddier: a 2026 review in the journal Lipids notes that the Dietary Guidelines for Americans for 2025 to 2030 count butter and beef tallow among “healthy” fats, food advice that it says does not fit the long-standing limit of saturated fat to under 10% of calories [21].