A Third of People May Have Low Levels of Key Dairy Nutrient - Scientist

Up to one-third of people may have low levels of a key nutrient found in dairy products, according to research led by a US scientist examining its role in metabolic health.1

Dr Stephanie Venn-Watson, a veterinary epidemiologist who previously served with the World Health Organization and the US Navy, says the findings may have particular relevance in New Zealand.

Research shows dairy remains a staple of many New Zealand diets, but consumption patterns have shifted over time. While New Zealanders still rank among the world’s highest per-capita consumers of milk, domestic consumption has gradually declined, with total milk intake falling 1% to 89 litres per person per year in 2025. Analysts attribute the trend to changing consumer preferences, including the growing popularity of reduced-fat dairy products and plant-based alternatives.2

Researchers say that the shift may have implications for levels of C15:0, also known as pentadecanoic acid, an odd-chain saturated fatty acid naturally present in milk fat and some fish.

In everyday diets, the compound is primarily found in foods such as whole milk, butter, cheese and other dairy products that contain natural milk fat.

Dr Venn-Watson says while once considered nutritionally insignificant, C15:0 has gained increasing scientific attention as researchers examine links between specific fatty acids, inflammation and long-term metabolic health.[3]

“C15:0 occurs naturally in dairy fat, but historically it received very little scientific attention because it was assumed to be nutritionally insignificant.

“More recent research suggests it may play a much more active role in maintaining metabolic balance than previously thought,” she says.

Several human studies have reported associations between higher circulating levels of odd-chain fatty acids such as C15:0 and lower risk of conditions including type 2 diabetes and cardiovascular disease.[4]

Dr Venn-Watson says scientists are increasingly examining individual fatty acids rather than treating all dietary fats as a single category.

“For many years dietary fats were grouped together in broad categories, but we are increasingly learning that individual fatty acids can have very different biological effects.

“That means understanding the role of compounds such as C15:0 could be important for long-term metabolic health,” she says.

The topic is attracting interest as metabolic disease continues to rise in many countries, including New Zealand. Ministry of Health data shows around one in three adults in New Zealand are classified as obese, while more than 300,000 people are estimated to be living with diabetes or pre-diabetes.[5]

Much of the scientific attention surrounding the fatty acid emerged through marine health research led by Dr Venn-Watson, who is widely regarded as the world’s leading expert on C15:0. The compound is considered the first essential fatty acid to be identified in more than 90 years.

Her research analysing ageing dolphin populations uncovered unexpected links between fatty acid levels and metabolic disease.

Dr Venn-Watson’s team examined decades of archived blood samples alongside controlled diet data and found that roughly one in three older dolphins developed metabolic conditions commonly associated with ageing in humans, including insulin resistance, abnormal lipid levels, chronic inflammation and fatty liver disease.[6]

She says the discovery emerged while researchers were analysing why some dolphins appeared to age more healthily than others.

“We were studying why some dolphins aged healthily while others developed metabolic conditions similar to those seen in humans.

Dr Venn-Watson says large-scale molecular analysis of the animals’ blood revealed one compound that consistently distinguished healthier dolphins from those experiencing metabolic decline.

“When we examined thousands of molecular markers in the blood samples, C15:0 consistently stood out as one of the strongest indicators associated with healthier animals,” she says.

“Animals with higher circulating levels tended to show fewer signs of inflammation and metabolic dysfunction,” she says.[7]

Subsequent laboratory studies have suggested the fatty acid may influence several biological pathways linked to cellular health, including mitochondrial function, inflammation signalling and lipid metabolism.[8]

Scientists say growing international interest in individual milk components reflects a broader shift toward functional dairy ingredients, where specific fatty acids, peptides and other bioactive compounds are studied for their potential health effects rather than treating milk fat as a single nutritional category.[9]

Dr Venn-Watson says the research reflects a broader shift in nutrition science toward understanding individual nutrients in greater detail.

“We are only beginning to understand how specific nutrients interact with metabolic systems in the body.

“As research tools improve, it is likely that additional compounds previously considered minor components of food will turn out to play important roles in health,” she says.

Dr Venn-Watson says that the emerging science should not be interpreted as evidence that people should dramatically increase dairy consumption.

“The findings highlight how much remains to be understood about the biological effects of individual fatty acids and the importance of examining nutrition at a more detailed biochemical level,” she says.

“Dairy fat is the main dietary source of C15:0, but it also contains higher levels of another fatty acid called C16:0.

“A recent clinical trial found that increasing dairy fat intake raised C15:0 levels, which were associated with improved vascular function. However, the same study also showed increases in C16:0, which were linked to higher blood pressure,” she says.[10]

-Ends-

[1] Venn-Watson, S., Lumpkin, R., & Dennis, E. A. (2020). Efficacy of dietary odd-chain saturated fatty acid pentadecanoic acid parallels broad associated health benefits in humans: could it be essential? Scientific Reports, 10(1), 8161.

[2] IBISWorld - industry market research, reports, and statistics. (n.d.).

[3] Venn-Watson, S., Lumpkin, R., & Dennis, E. A. (2020). Efficacy of dietary odd-chain saturated fatty acid pentadecanoic acid parallels broad associated health benefits in humans: could it be essential? Scientific Reports, 10(1), 8161.

[4] Huang, L., Lin, J., Aris, I. M., Yang, G., Chen, W., & Li, L. (2019). Circulating Saturated Fatty Acids and Incident Type 2 Diabetes: A Systematic Review and Meta-Analysis. Nutrients, 11(5), 998.

[5] Obesity | Ministry of Health NZ. (2026, February 10). Ministry of Health NZ.

[6] Venn-Watson, S., Lumpkin, R., & Dennis, E. A. (2020). Efficacy of dietary odd-chain saturated fatty acid pentadecanoic acid parallels broad associated health benefits in humans: could it be essential? Scientific Reports, 10(1), 8161.

[7] Venn-Watson, S., Lumpkin, R., & Dennis, E. A. (2020). Efficacy of dietary odd-chain saturated fatty acid pentadecanoic acid parallels broad associated health benefits in humans: could it be essential? Scientific Reports, 10(1), 8161.

[8] Venn-Watson, S., Lumpkin, R., & Dennis, E. A. (2020). Efficacy of dietary odd-chain saturated fatty acid pentadecanoic acid parallels broad associated health benefits in humans: could it be essential? Scientific Reports, 10(1), 8161.

[9] Gómez-Cortés, P., Juárez, M., & De La Fuente, M. A. (2018). Milk fatty acids and potential health benefits: An updated vision. Trends in Food Science & Technology, 81, 1–9.

[10] Arghavani, H., Bilodeau, J., & Rudkowska, I. (2025). Impact of dairy intake on circulating fatty acids and associations with blood pressure: A randomized crossover trial. Nutrition Metabolism and Cardiovascular Diseases, 35(9), 104112.