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Dairy: a new nutrient vehicle?

Researchers are finding new roles for milk in nutraceuticals. Is this the end of the pill as we know it? Bill Haines reports on a study that looked at the chemical stability of selected supplements over time and under different storage conditions when added to milk and processed by different means

Every parent knows the drill: ?Drink your milk,? we say to our kids, ?if you want to grow up big and strong.?

Now a new twist on this familiar scene could be coming, of children reminding ageing parents to drink their milk if they want to stay healthy — and to drink milk that packs added nutrients to help stave off certain illnesses. Milk is being prepped for a potential new role that could elevate this player in health and wellness to an innovative position in functional foods.

Researchers at the University of Minnesota have been investigating milk as a vehicle for dietary supplements that may be helpful in combating certain conditions of ageing, including arthritis, heart disease, macular degeneration, osteoporosis and cancer. Their goal is to evaluate the stability of specific nutrients in milk, laying the groundwork for potential nutraceutical products.

Based on the researchers? findings, it may not be long before it is feasible to provide seniors with, for example, a glucosamine-and-milk composition (with appropriate dosages and shelf life). Many Europeans already do something similar when they consume small, probiotic-infused yoghurt drinks, which are accepted as a quick way to ingest beneficial bacteria for gut health. In the US, Dannon offers its DanActive cultured dairy drink, a 3.3oz beverage containing a blend of live cultures that the company says are clinically tested to support immunity.

Although adults of many ages could enjoy these drinkable milk-based nutraceuticals, the research group primarily had seniors in mind because older people often find it difficult to swallow supplement pills, says lead researcher Theodore P Labuza, PhD, professor of food science and nutrition at the University of Minnesota. The attraction of milk-based nutraceuticals is they?re easier to consume, he notes. Furthermore, using a familiar food such as nutrient-rich milk as the delivery system brings a comfort level to a nutraceutical while providing other nutrients such as calcium, potassium, protein and more.

Different temperatures and storage times
Where Labuza?s concept differs from multivitamin supplements is his focus on finding a stable vehicle, such as milk, to carry supplements that address specific health concerns associated with ageing, such as arthritis and cancer.

The project tested only dietary supplements for which clinical evidence suggests may have a positive effect on certain conditions: glucosamine, chondroitin sulfate, lactoferrin, soy isoflavones and creatine. Both glucosamine and chondroitin sulfate may aid in increasing joint mobility and decreasing arthritic pain. Emerging data suggests that lactoferrin may help improve the immune system. Soy isoflavones may provide benefits for menopause, heart disease and osteoporosis. Creatine may improve muscle mass. The research team did not include compounds from herbal sources, since the amount of active ingredients in herbal products can vary widely, depending on growing and storage conditions.

This study looked at the chemical stability of the selected supplements over time and under different storage conditions when added to 4oz (about 100ml) servings of milk and processed by different means. The amount of supplement varied; the research team used 1.2mg/ml of soy isoflavones, 2mg/ml of lactoferrin, 5mg/ml of chondroitin, 6mg/ml of glucosamine or 7.3mg/ml of creatine. (The targeted dose of each supplement per serving was 60mg for soy isoflavones, 250mg for lactoferrin, 600mg for chondroitin, 750mg for glucosamine and 800mg for creatine.)

The supplement-enhanced milk was then stored under different temperatures — refrigerated (4oC), room temperature (21oC) and ?thermal abuse? conditions (40oC). The study focused on answering two questions: what is the stability limits of various supplements during pasteurising or sterilising in the presence of milk? And, what?s the viability of these supplements over time under different storage conditions?

After treatment, the milk was stored for up to 28 weeks. Sampling was conducted immediately after treatment and at intervals of four, eight and 16 weeks.

One factor in the study was potential interactions between components in milk and the supplemented nutrient. Milk can have a buffering effect that protects against chemical degradation of the supplement during thermal processing. However, interactions can also take place between the supplement and milk proteins or lactose that may lead to gelation or precipitation. During storage, the preparation containing glucosamine did display a loss in that compound over time; one possible interpretation is that the loss could be the result of an interaction with milk components, although that supposition has not been proven.

The project is currently in the final evaluation stages. To date, Labuza has found that stable, milk-based beverages can be made with all of the evaluated dietary supplements by pasteurisation, ultra-high-temperature (UHT) processing, or a combination of membrane sterilisation and aseptic filling. The team learned that:

  • Isoflavones proved stable at pasteurisation, sterilisation and UHT processing temperatures, and were fully present even after seven months at room temperature storage.
  • Glucosamine degraded quickly when stored at room temperature ? under refrigeration, about 20 per cent of the supplement had degraded after eight weeks. These results suggest that the best way to present this dietary supplement in a milk matrix might be to cold-sterilise the glucosamine and then mix it aseptically with UHT-processed milk and store it under refrigeration.
  • Lactoferrin was stable throughout pasteurisation but degraded completely when subjected to high heat. The best format for lactoferrin, Labuza suggests, could be cold-sterilising this supplement before mixing it aseptically with UHT-processed milk. Such a mixture proved stable in storage for at least four months under refrigeration or at room temperature.
  • Creatine appears to be stable throughout pasteurisation and loses less than five per cent under UHT processing. Testing of its shelf-life performance is still under way.

To summarize, long storage stability is possible at room temperature for soy isoflavones, chondroitin and lactoferrin products. Glucosamine is reasonably stable at 4oC storage but demonstrates 20 per cent loss after two months. The results for creatine will be available shortly. Sensory testing of the milk-based dietary supplements has yet to be conducted.

Milk on the go
The next step, Labuza says, could be a manufacturer picking up on this idea and taking it to market. On store shelves, Labuza envisions a small version of today?s milk-on-the-go products — that is, small plastic bottles offering a 100ml (about 4oz) serving. That would be enough for a quick dose but not for use as a beverage.

Labuza says adults motivated to preserve their vitality may likely have an interest in this offering. ?Over 55 is a huge age group and it?s growing,? says Labuza. ?I?m over 55,? he laughs, ?so I thought it was a good thing to work on.?

Labuza?s research was sponsored by Dairy Management Inc and funded by American dairy farmers.

Bill Haines is vice president of product innovation at Dairy Management Inc. Respond: [email protected] All correspondence will be forwarded to the author.

A large and growing market
Two thirds of Americans currently partake of nutraceuticals in some form, according to 2002 research by the Food Marketing Institute (FMI). This practice has helped turn these products into a $28 billion category (Mintel International Group, 2004).

Other FMI research found that shoppers aged 40-49 scored highest on FMI?s Self-Care Index, indicating they are the consumer group most likely to seek out health information and buy products to treat themselves. Given this strong inclination within an age group headed for retirement age — the vast demographic bulge known as the Baby Boom generation — the potential for dairy-based nutraceutical beverages looks healthy.


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